Bitcoin Wiki - User contributions [en]

Paper wallet

2019-02-07T17:28:01Z

Holy-Fire: Revert multiple edits by User:Belcher, which are based on a very narrow view of what paper wallets are, and misunderstanding of their use cases.

[[File:FirstBitcoinBills.jpg|thumb|right|200px|Casascius holding early paper wallets]]

In the most specific sense, a '''paper wallet''' is a document containing all of the data necessary to generate any number of Bitcoin [[private key]]s, forming a wallet of keys. However, people often use the term to mean ''any'' way of storing bitcoins offline as a physical document. This second definition also includes '''paper keys''' and '''redeemable codes'''. A paper key is a single key written on paper that is used multiple times like a wallet (this is strongly [[address reuse|discouraged]]). A redeemable code is a single key intended to be funded and "redeemed" only once: these are commonly used for gifts and as part of physical Bitcoin coins/notes.

Storing bitcoins on paper wallets is not safe unless very strict security precautions are undertaken during their initial preparation. (See below.)

__TOC__

== Security overview ==

Generating paper wallets is not recommended from an online PC. Malware malware on the PC may be able to steal your paper wallet keys.

Even if you generate paper wallets securely, they are still vulnerable to loss and theft.

Unencrypted paper wallets must be kept safe like jewels or cash.

For additional security paper wallets can be split into shares, requiring X of Y shares (e.g., 3 out of 5) to reassemble the secret key.

==Use cases==

===Tips and gifts===

By creating a keypair, one can store bitcoins on a physical medium to be left as a tip or a gift.
The recipient then sweeps the private key to their own wallet.

===Physical tokens===

A trusted provider can hide the private key inside a tamper-resistant token, and issue them as a form of bitcoins.
This requires those who accept it as payment to trust that when the provider produced the tokens, they loaded them with the correct amount of bitcoins, and that they have not been tampered with since then.
To redeem the bitcoin value, the token must be destroyed to access the private key.
Often a bitcoin address is embedded on the outside visible, but there is no guarantee (without destroying the token) that this matches the private key inside, or, even if it does, that the private key is not replicated on multiple tokens or saved by the producer.

===Wallets===

Proper paper wallets are often a very secure way of storing bitcoins, since they are not typically exposed to malware. They can also be easily stored securely in safes and safe deposit boxes. However, it may be more difficult to securely "backup" paper wallets, and due to the current sub-optimal software support, it may be easier to make a mistake that causes loss of bitcoins.

Sometimes people try to use single keys as true bitcoin wallets. However [[address reuse]] is very bad for privacy and security. Because of this, one is forced to choose between hazardous options:
* '''Use the key only once to receive, and only once to send the full amount.''' This requires the user to know the full amount he wants to store in advance, and often leads to the next situation:
* '''Create multiple keys.''' By using more than one key, the user can receive more than once using a different address each time, including using new addresses for change. This is very complicated, and makes it easy to accidentally reuse addresses, produce the wrong change/fee combination, lose some keys, spend hours searching for the right key, etc. Not even skilled bitcoin experts are comfortable managing their own keys manually like this.

Therefore, it is highly recommended that you use proper paper wallets which allow you to generate an infinite number of addresses from a single seed.

==Encoding/formatting==

[[File:BitcoinPaperWallet-sample.jpg|thumb|right|300px|Paper keypair with private key secured beneath folds]]
[[File:PaperWallets-offlineaddress-com.png|200px|thumb|right|Paper keypair]]
Proper, multi-key paper wallets usually take the form of a multi-word [[Deterministic wallet | HD wallet]] seed mnemonic. The list of several words corresponds to some binary data that is used to generate all of the addresses. Words are used to make it easier to avoid and correct errors. Trying to memorize an entire seed mnemonic is very difficult and is generally not recommended.

A single key (for use in insecure single-key paper wallets or redeemable codes) can be represented in several formats, but typically the Wallet Import Format (WIF) is used, since keys represented that way are very short (51 characters) and thus easy to re-enter when importing or "sweeping" it for withdrawal.

==Creation of a paper wallet==

===Generation of secure keys===

The private seed is used to prove your right to spend the bitcoins transferred to the paper wallet, and as such should be kept hidden and secret.
If the private seed on a paper wallet is exposed (for example in a photograph) then the wallet may be used by anyone who sees it.
To guard against accidental revelation, the private key displayed on the paper wallet may be encrypted or split into several different parts (for example using [https://en.wikipedia.org/wiki/Shamir%27s_Secret_Sharing Shamir's secret sharing scheme]).
At the very least, the private key should be well hidden e.g. by folding the wallet in half and sealing it shut.

Currently, at least [[Armory]] and [[Electrum]] support generating mnemonic codes for their wallets, which can be written down or printed to make a multi-key paper wallet.

Several tools exist for producing single keys, including [[Bitcoin Address Utility]], [[vanitygen]], and [[Cwallet]]. Again, using single keys for anything except one-time ''transfers'' of bitcoins is strongly [[address reuse|discouraged]].

===Web-based key generators===

Some websites feature free open-source client-side keypair/wallet generators written in JavaScript.
Keypairs/wallets generated by JavaScript or using websites are inherently weak and insecure, and unless the code of the website is audited every time it is used, it may leak the generated keys back to the server—especially if un-audited Javascript is downloaded and run locally.
Even with careful code auditing, browser plugins or other websites may compromise the environment.

===Recommendations===
* Disconnecting from the Internet guarantees that that the paper wallet generator is truly self-contained and isn't transmitting your keys online.
* Verifying the integrity of the code (and the trustworthiness of the author) is important to make sure a hacker hasn't modified the download so that it generates predictable seeds instead of truly random ones.
* Remember, spyware and viruses often attempt to monitor your computer activities so that their authors can steal from you. They are interested in passwords to online accounts, and anything of value. Bitcoin wallets are something of value that have already been targeted by malware. If your computer is infected with spyware or viruses - even if there are no symptoms, or your antivirus isn't reporting anything - then anything you type, view, or save on your computer, could potentially be stolen by someone remotely controlling your computer. Your private seed can then be intercepted while you enter it, so only enter a Bitcoin private seed into your computer when you are certain it is secure (such as a fresh boot of a LiveCD).
* The wallet should never be saved to a computer hard drive or sent via email or other network connections. You should also never scan/type your key into your computer, except at the moment you are using it.
* If possible, the wallet should be kept hidden, for example by using [[BIP_0038|BIP38]] encryption (single keys only), and/or by folding the paper to hide the private key so that a photograph or photocopy of it will not reveal or replicate the private key.
* A web-based generator should not be used.
* A generator should use an appropriate source of random numbers (entropy). This means that the generated keys aren't predictable. If the addresses come from a predictable or partially-predictable patterns like pseudorandom numbers <ref>[https://en.wikipedia.org/wiki/Pseudorandomness#Cryptography Pseudorandomness] '' is not enough for strong cryptography''</ref>, someone else who can predict the pattern can steal the balance. Randomness should NEVER be human generated, as the human brain is incapable of secure entropy.
* Remember that unlike wallets (paper or otherwise), a single paper key is only good to receive a single payment, and must be redeemed in its entirety.

===Printer Security===

Some advanced printers have internal storage (even hard drives) that preserve copies of printouts. This is a risk if someone gets access to your printer, or if you dispose of your printer. There is also the possibility that a smart enough printer can be hacked. (Consider [http://en.wikipedia.org/wiki/Stuxnet StuxNet] which was able to rewrite the firmware of non-computer devices indirectly connected to the Internet) If this concerns you, use a "dumb" printer, and never let your printer have access to the Internet or to an Internet-connected computer.

====Handwriting====

An alternative using a printer for paper wallets is to write the private key and address with your own hand. [[Base58Check]] encoding used for Bitcoin addresses and private keys specifically excludes characters that look similar like 0OIl. The mnemonic recovery seeds used by wallets like [[Armory]] and [[Electrum]] are also suitable to be written by hand.

==Redeeming Keys and Withdrawing Funds==

This section applies only to single-key paper "wallets".

Paper keys, when used as wallets, are very different from wallets such as Bitcoin Core in that there is only one address in a paper key rather than a hundred or more online keys that are managed with full software assistance from Bitcoin Core.

There are various methods for copying the private key data to other wallets.
* bitcoind supports an "importprivkey" RPC method for this purpose.
* Bitcoin-Qt's debug console can also be used in a similar way (see also [[How to import private keys in Bitcoin Core 0.7+]]).
* [[BlockChain.info]] and [[Armory]] can also import them directly into wallets.
* [http://MyCelium.com/download Mycelium] is a Android mobile wallet with an easy to use "cold storage" spending function. It is also available via Android and iTunes playstore. The iTunes version may not yet support cold storage spending.

Note that importing a private key that may be compromised can result in the entire wallet becoming insecure. For this reason, sweeping (or sending the entire amount to a fresh address) is generally recommended over plain importing.

==References==
<references />

==See Also==

* [[Cold storage]]
* [[Private key]]

* [[Securing_your_wallet#Paper_Wallets]]

* [https://www.reddit.com/r/Bitcoin/comments/1c9xr7/psa_using_paper_wallets_understanding_change/ Reddit warning on redeeming paper wallets]

* [[How to import private keys]]

* [[Casascius physical bitcoins]]

[[Category:Security]]

[[es:Monedero de papel]]

User talk:Midnightmagic

2018-01-09T11:45:13Z

Holy-Fire: /* Trade page */ new section

Hello, thank you for your message on my talk page. Upon reflection I wholeheartedly agree, I acted improperly, and let groupthink / personal attitudes get the better of me. This won't happen again. Best, [[User:Gladoscc|Gladoscc]] ([[User talk:Gladoscc|talk]]) 04:24, 1 March 2015 (UTC)

I replied [[User talk:Bitcoinomy|here]], thanks. [[User:Bitcoinomy|Bitcoinomy]] ([[User talk:Bitcoinomy|talk]]) 12:45, 19 August 2015 (UTC)

== Comparison of cryptocurrencies ==

Thank you for taking your time. I added more questions in
* https://en.bitcoin.it/wiki/Talk:Comparison_of_cryptocurrencies#Scamcoin_removals again
* https://en.bitcoin.it/wiki/Talk:Comparison_of_cryptocurrencies#Anonymity
--[[User:Davidhedlund|Davidhedlund]] ([[User talk:Davidhedlund|talk]]) 19:09, 4 October 2017 (UTC)

== Bitcoin Cash ==

I added your text to https://en.bitcoin.it/wiki/Bitcoin_Cash

== Blockonomics page removed ==

Hi,

Can you please explain the reasons for this when other page like https://en.bitcoin.it/wiki/CoinGate, https://en.bitcoin.it/wiki/BitPay and https://en.bitcoin.it/wiki/Gourl still exist

: Yeah, exactly. BitPay is going to stay but be modified to describe their current position on S2X. That is an important topic for Bitcoin users. I haven't gotten to deleting everything yet. I'm only one person, and I don't like doing it all at once. Too many people complaining. Also, sign your name next time. [[User:Midnightmagic|Midnightmagic]] ([[User talk:Midnightmagic|talk]]) 04:11, 11 October 2017 (UTC)

== Trade page ==

Hello,

It seems you have recently deleted the page "Trade".

I believe that was a horribly misguided decision. While the page is hopelessly outdated and of no practical use, its importance as a historical reference is tremendous, especially its edit history. The history seems to be inaccessible now that it has been deleted.

I implore you to restore the page and simply edit it to include a deprecation notice instead of the original list.

Thanks. [[User:Holy-Fire|Holy-Fire]] ([[User talk:Holy-Fire|talk]]) 11:45, 9 January 2018 (UTC)

Offline transactions

2017-08-17T20:02:59Z

Holy-Fire: I like singing, but signing is a more appropriate thing to do with a transaction.

The term "offline transaction" refers to the practice of keeping the private keys on an offline device (not connected to the internet), and signing on individuals transactions. The signature is then copy-pasted from this device into a connected device, and broadcast into the Bitcoin network.

Assuming the offline computer is malware-free is easier than a connected device. If this assumption is held, then this practice is virtually risk-free of bitcoin theft.

Offline transactions can also be used when talking to an [[Overlay Network]] (e.g. [http://stratum.bitcoin.cz/ Stratum]) or equivalent - an ultra thin client can send only signatures to the Overlay server, thus mitigating the risk of a malicious server running away with one's BTC.

The Israeli Bitcoin Association

2013-11-27T21:50:58Z

Holy-Fire: Additions

Also known as איגוד הביטקוין הישראלי.

The IBA is still in the process of setting up.

* [https://trello.com/b/1CdF7NqV/israeli-bitcoin-foundation Trello]
* [http://www.bitcoin.org.il/ Homepage] (Hebrew)
* Board members:
** [[Meni Rosenfeld]]
** [[Ron Gross]]
** [[Jonathan Rouach]]
** [[Eli Sklar]]
** [[Eden Shochat]]

* Observers:
** [[Yoni Assia]]
** [[Nimrod Lehavi]]

* Others:
** [[Jonathan Klinger]] - Legal Council
** [[Shai Tal]] - Bookkeeper
** [[Ariel Horwitz]] - Community Manager
** "Noam" - IT Manager

[[Category:nonprofit]]

Economic majority

2013-11-13T17:35:31Z

Holy-Fire:

The theory that the power to control the Bitcoin protocol is held by those able and willing to offer things of value for bitcoins (be it goods, services or other currencies).

As long as mining is conducted for economic gain, then any change adopted by the miners needs to be supported by the '''economic majority''' for it to be successfully implemented.

While miners could adopt changes that are not welcomed by those who want bitcoins and start mining using the changes, their mined coins might not be accepted by users that refuse to adopt the changes. Thus those miners would then, in that instance, not gain economically from adopting the change. This scenario exists regardless of whether or not the miners adopting the change had 51% of the hashing strength.

So the ability for a protocol change to be successfully implemented ultimately rests with those who accept bitcoins in exchange for value. Generally those will be the merchants.

Credit goes to Meni Rosenfield for first coining the term<ref>[http://bitcoin.stackexchange.com/questions/3945/how-could-the-bitcoin-protocol-be-changed-has-this-ever-occurred#comment4983_3948 How could the bitcoin protocol be changed? Has this ever occurred?]</ref>.

==See Also==

* [http://bitcoin.stackexchange.com/questions/8285 Is Bitcoin's Economic Majority those who already own coins or those who will buy or keep coins?] on Bitcoin Stack Exchange

==References==
<references />

Economic majority

2013-08-08T14:22:27Z

Holy-Fire:

The theory that the power to control the Bitcoin protocol is held by those able and willing to offer things of value for bitcoins (be it goods, services or other currencies).

As long as mining is conducted for economic gain, then any change adopted by the miners needs to be supported by the '''economic majority''' for it to be successfully implemented.

While miners could adopt changes that are not welcomed by those holding bitcoins and start mining using the changes, their mined coins might not be accepted by users that refuse to adopt the changes. Thus those miners would then, in that instance, not gain economically from adopting the change. This scenario exists regardless of whether or not the miners adopting the change had 51% of the hashing strength.

So the ability for a protocol change to be successfully implemented ultimately rests with those who accept bitcoins in exchange for value. Generally those will be the merchants.

Credit goes to Meni Rosenfield for first coining the term<ref>[http://bitcoin.stackexchange.com/questions/3945/how-could-the-bitcoin-protocol-be-changed-has-this-ever-occurred#comment4983_3948 How could the bitcoin protocol be changed? Has this ever occurred?]</ref>.

==References==
<references />

Talk:Economic majority

2013-08-08T13:38:49Z

Holy-Fire: /* Those who already hold coins vs. those who will acquire coins */

== Contracts and Economic Majority ==

"So the ability for a protocol change to be successfully implemented ultimately rests with those who accept bitcoins in exchange for value."
"So by default, ultimately a protocol change has to be welcomed by those who hold bitcoins."

These are, of course, probably two different types of people in the near- to medium-term.

Agents who accept BTC for value, "vendors," are generally going to be most concerned with price stability; they want to be able to quote prices that are predictable. Agents who hold BTC for more than the short term, at this time, are mostly speculators, and they want appreciation. There's nothing that prevents us, technologically-advanced folk that we are, from producing new price quotes daily (or every minute for that matter), like a gas station, based on any number of underlying market conditions -- convertibility to sovereign currency, input commodity, specie, whatever -- but it'd be a huge cultural shift for a contractor, who's primary input is labor, to have to quote a different rate on a regular basis.

Also worth considering is that there is a whole class of users that don't exist now but probably will in the future: people who hold futures contracts denominated in BTC, in and out of the money. A service provider who makes a long term deal -- for instance, his wages over the term of a contract -- will want BTC's values to stay as predictable as possible, just as commodity vendors at the end of a growing season will want predictability, if not BTC deflation relative to his negotiated deal. On the other side of the equation are people who hold out-of-the-money contracts on the value of the BTC, which is just a fancy way of saying "debtors." Loans aren't a BTC phenomenon yet, and with the engineered deflation they aren't liable to be a phenomenon for a while, but employers and commodity speculator/brokers, people who negotiate long-term deals in BTCs, will likely be constantly trying to bend the value curve flatter, because it means they win more value.

Contracts and futures can hold significant notional value, perhaps several multiples of the total capitalization of the market.

'''Question:''' Do people who don't hold BTC, but hold contracts in BTC, deserve a say in changes? And how would we recognize this? Do we favor people who hold in-the-money bets, like employees or lenders, or out-of-the-money bets, like debtors or employers.
--[[User:Sigaba|Sigaba]] ([[User talk:Sigaba|talk]]) 05:19, 13 August 2012 (GMT)

== Those who already hold coins vs. those who will acquire coins ==

The Economic Majority theory says that the power to control the Bitcoin protocol is held by those who [own] bitcoins.

But the article then goes on to read:

The ability for a protocol change to be successfully implemented ultimately rests with those who accept bitcoins in exchange for value.
So that refers to investors and those who aren't immediately spending or cashing out the coins they receive as income or revenue.

But that power doesn't lie with those who already hold the coins but instead it lies with those who are willing to accept the newly issued coins under the revised protocol or coins with taint from coins issued under a revised protocol.

So, is the Economic Majority those that already hold bitcoins or is it instead just those who will hold the bitcoins generated following a change to the protocol? If so, how would that be best worded?

This question was also [http://bitcoin.stackexchange.com/questions/8285 raised] on Bitcoin Stack Exchange.
- [[User:Sgornick|Sgornick]] ([[User talk:Sgornick|talk]]) 02:52, 16 March 2013 (GMT)

:Actually, the people who already have bitcoins are not a significant part at all in the economic majority. Starting the page with "by those who hold bitcoins" is completely wrong.
:The constituents of the economic majority are traders/investors willing to buy bitcoins for other currencies and merchants willing to accept bitcoins for products. Since many of those do it by proxy, the proxies (exchanges, payment processors and other services) have a large influence.
:I think this requires a complete rewrite of the page. [[User:Holy-Fire|Holy-Fire]] ([[User talk:Holy-Fire|talk]]) 09:12, 30 May 2013 (GMT)
:I removed the following part:
::''Just as a consumer has the ability to boycott a business if the consumer has a problem with how they operate, Bitcoin consumers have the ability to boycott merchants as well. Thus a Bitcoin merchant might not adopt a protocol change that would not be welcomed by its consumers.''
::''So by default, ultimately a protocol change has to be welcomed by those who hold bitcoins.''
:I don't believe it is true. People who hold bitcoins have very little bargaining power - if most everyone else switches to a new protocol, stakeholders need to follow suit or their bitcoins will be worthless. [[User:Holy-Fire|Holy-Fire]] ([[User talk:Holy-Fire|talk]]) 13:38, 8 August 2013 (GMT)

Talk:Economic majority

2013-05-30T09:12:47Z

Holy-Fire: /* Those who already hold coins vs. those who will acquire coins */

Promotional graphics

2013-02-27T19:29:55Z

Holy-Fire: + non-English

Bitcoin-related graphics used for promoting bitcoin either for online use, retail display or other promotional purpose. For graphics in languages other than English, see [[Promotional graphics (non-English)]].

==Orange style==
===Logo alone===
[[{{ns:file}}:BC Logo .png‎]]

[http://weusecoins.jp/remote/en.bitcoin.it/promotional_graphics SVG and higher resolutions]

===Logo with text===
[[{{ns:file}}:BC Logotype.png‎]]

[[{{ns:file}}:BC Logotype Reverse.png]]

==="We love Bitcoin" Graphics===
[[{{ns:file}}:Lv BCorg 128px.png]]
[[{{ns:file}}:WeLv BC 48px.png]]
[[{{ns:file}}:WeLv BC 128px.png]]
[[{{ns:file}}:WeLv BC Badge 128px.png]]
===Bitcoin Accepted Here Buttons===
====Normal size====
[[{{ns:file}}:BC_Rnd_64px.png‎]]
[[{{ns:file}}:BC 64px.png‎]]
[[{{ns:file}}:BC nBG 64px.png‎]]
[[{{ns:file}}:BC RnBG 64px.png‎]]
====High resolution====
[[{{ns:file}}:bitcoin_accepted_here_printable.png|x200px‎]]

==Euro style==
[[{{ns:file}}:Bitcoin euro.png]]

==Gold style==
[[{{ns:file}}:Bitcoin.png]]

==Ƀ: Another Bitcoin Identity==
* [[{{ns:file}}:CircleBitcoin.png]]
* [[{{ns:file}}:Pennant.png]]
* [[{{ns:file}}:RibbonDonateBitcoin.png]]
* [[{{ns:file}}:GoldenAcceptedHereBitcoin.png]]

 Ƀ graphic elements are available in SVG format on the dedicated [http://www.ecogex.com/bitcoin/ project page].

==External Links==

* [https://bitcointalk.org/index.php?topic=64.msg7415#msg7415 New icon/logo] (SVG of the gold bitcoin / logo)
* [https://bitcointalk.org/index.php?topic=4331.0 Bigger "B" versions of Bitcoin logotypes]
* [https://bitcointalk.org/index.php?topic=9562.20 Ƀ Another Bitcoin identity]
* [https://bitcointalk.org/index.php?topic=1631.0 More Bitcoin logos, buttons, and also some other graphics]
* [https://bitcointalk.org/index.php?topic=45.msg479#msg479 Make your "we accept Bitcoin" logo]
* [http://img340.imageshack.us/img340/7210/onwhitem.jpg Bitcoin Decentralized P2P Currency logo]
* [http://agora.io/wp-content/uploads/2011/03/BitcoinFreeMoney250x100.png Liberty starts with free money logo]
* [https://bitcointalk.org/index.php?topic=6412.0 Made a Bitcoin icon, PDF included]
* [https://bitcointalk.org/index.php?topic=6455.0 In cryptography we trust (yet another Bitcoin icon)]
* [http://bitbash.blogspot.com/2011/04/bitcoin-icons.html Bitcoin icons] from Bitbash
* [http://lts.cr/d8d Bitcoin Graphics] zip
* [http://www.promotionalcodes.org.uk/26970/what-is-bitcoin/ What is Bitcoin? (Infographic)]
* [http://carbonism.deviantart.com/gallery carbonism's deviantART gallery]
* [http://handsomecode.tumblr.com/post/6565610892/designing-a-better-bitcoin-identity Handsome Code Better Bitcoin]
* [https://bitcointalk.org/index.php?topic=32273.0 Public Domain Bitcoin Icons/Graphics for you!]
* [http://imgur.com/o5hHQ Stack of bitcoins]
* [https://bitcointalk.org/?topic=1756.0 Bitcoin Graphics in Vector Format (Illustrator)]

==See Also==

* [[Bitcoin symbol]]

[[Category:Marketing]]

Promotional graphics (non-English)

2013-02-27T19:29:13Z

Holy-Fire: Create page, add Hebrew

=Hebrew=
[[File:כאן_מכבדים_ביטקוין.JPG]]

File:כאן מכבדים ביטקוין.JPG

2013-02-27T19:28:23Z

Holy-Fire: A "Bitcoin accepted here" sign in Hebrew

== Summary ==
A "Bitcoin accepted here" sign in Hebrew
== Licensing ==
{{subst:nld}}

Exit Address

2013-01-16T15:42:52Z

Holy-Fire: typo

Exit addresses (first described [http://www.reddit.com/r/Bitcoin/comments/ohfxw/update_mt_gox_steals_from_tor_users_now_i_can_not/c3ha5li here]) are defined as follows: "When you create an account with a site, you should be able to enter an address that, should anything go wrong, your coins will be sent to. Deepbit, for example has an option that will let you 'lock your payments address forever' meaning, even if someone hijacks your account, they won't be able to withdraw money anywhere."

Many members of the bitcoin community have advocated that any service accepting bitcoin deposits (as opposed to payments -- i.e. exchanges, etc) ought to include an exit address facility, and allow enactment of exit address policy at any time. This would avoid the conflict of interest inherent in "anti-money-laundering" account freezures, whereby the exchange ''actually books a profit under accepted accounting practices'' as a result of balances inheriting from accounts abandoned in response to account freezure (once the statue of limitations on embezzlement expires).

[[Category:Vocabulary]]

[[es:Dirección de escape]]

User talk:Holy-Fire

2013-01-06T18:34:17Z

Holy-Fire: Removed Luke-jr's vandalism of my talk page

== Proof of Stake design outline ==

=== Constants (for example) ===
*POSGEN = 250000          // genesis block from which the fork (that includes the PoS protocol change) begins 
*SIGBLOCK = 100            // signatures block at every SIGBLOCK block 
*POWCONFIRMS = 6       // cementing rule for regular PoW after 12 blocks 
*POSPOWRATIO = 0.1     // proportion of the reward at each PoS checkpoint that goes to stake holders 
*STAKECUTOFF = 50       // must hold at least STAKECUTOFF bitcoins to provide a signature 

=== Protocol ===
Starting at POSGEN, every block B for which (B->count mod SIGBLOCK == 0) is considered to be a signatures block whose hash B->hash should be signed by privkeys that control at least STAKECUTOFF bitcoins, who would broadcast their signature via a message STAKEMSG to the Bitcoin network.

Each address should provide its STAKEMSG signature only once, to any branch that it saw (preferably a branch whose signatures block was signed with the most bitcoins so far), and it may choose to do saw anywhere between position B->count and (B->count)+SIGBLOCK (exclusive).

Nodes should re-broadcast these STAKEMSG messages that signed B->hash, and miners should include STAKEMSGs in the blocks between B->count and (B->count)+SIGBLOCK (exclusive). There would be an optional txn fee that the stakeholders can pay by attaching this fee to their STAKEMSGs, in order to give incentive to the miners to include STAKEMSGs in the blocks.

The coinbase (txn fees + reward subsidy) of block (B->count)+SIGBLOCK is divvied up as follows:
*(i) coinbase*POSPOWRATIO is divided among the stake holders who signed block B->count
*(ii) coinbase*(1-POSPOWRATIO) goes to the miner who generated the block

Note:
*In (i) we divide proportionally among stakeholders according to the amount of bitcoins that they controlled at block B->count

An address must have at least STAKECUTOFF bitcoins at block B->count in order to to provide a STAKEMSG. This means for example that if an address with more than STAKECUTOFF bitcoins has transferred all of its bitcoin the an empty address between B->count and (B->count)+SIGBLOCK then this address can still provide a STAKEMSG after this txn, but the empty address cannot because at block B->count it had 0 bitcoins.

Each ECDSA signature is 512 bits, the total number of bitcoins is 21000000, so 64 bytes * 21000000/STAKECUTOFF gives a theoretical limit of about 26 megabytes for the total size of STAKEMSGs in SIGBLOCK blocks, assuming that STAKECUTOFF==50 (the ECDSA pubkey can be extracted from the signature, therefore we can assume that the overhead is small). The theoretical limit is the worst-case scenario, in practice it's expected that addresses that control much more than STAKECUTOFF would participate in order to get higher proportion of the reward, etc.

Nodes should refuse to switch to a different branch with higher PoW difficulty if that forked branch starts more than POWCONFIRMS blocks before their current branch. The advantage of this is that it provides good security from double-spending by an attacker who prepares a secret fork, i.e. if after more than POWCONFIRMS you see that the distributed mining power continues to work on the branch that you have then it gives confidence that an attacker couldn't reverse a txn that occured in those POWCONFIRMS blocks. The disadvantage is that an attacker could try to create havoc and dilute the distributed mining power, by releasing his competing fork of POWCONFIRMS blocks and splitting the nodes into different branches because of network propagation time, but at the next signatures block after at most SIGBLOCK blocks it is highly likely that the network will re-unite.

Nodes should switch to a branch which replaces more than SIGBLOCK of the blocks in their current branch only if it has more signature blocks, and the sum of all bitcoins controlled by the addresses that provided the signatures in these blocks is larger (if an address participated in several of these signatures blocks then it is counted multiple times in the sum). Here too the advantage is that you can much more secure from double-spending attacks if the height of the relevant txn is more than N*SIGBLOCK blocks, because an attacker would have to collude with malicious stakeholders N times (as well as needing hashpower to create a secret fork of more than N*SIGBLOCK PoW blocks) in order to reverse this txn.

Another advantage is that the signatures blocks may be regarded as checkpoints, so they could replace the need for harcoded developers' checkpoints in the official client, which protects from malicious developers.

=== Client behavior (+more protocol rules) ===

We wish to alleviate the risk that the stakeholders take when they need to use their passphrase to provide signatures, especially when the addresses that they control hold large amounts of bitcoins.
Additionally, it's preferred that the client application would behave automatically instead of prompting for passphrase at every signatures block.

We basically want a digital signatures scheme in which the keygen generates a triple (privkey1,privkey2,pubkey0) where privkey1 and privkey2 are unrelated to each other, you can sign either with privkey1 or with privkey2, and verify the resulting signature with pubkey0. It'd be used for PoS by using privkey1 to do actual txns and using privkey2 only for providing the PoS signatures to the signatures blocks. This means that if privkey2 gets stolen then it doesn't amount to much, you can transfer your bitcoins to another address and re-generate a new privkey2 for it, so it's ok to store privkey2 in the clear.

We cannot implement this scheme directly with ECDSA, but we can do something that's pretty close: simply by having two pairs (privkey1,pubkey1) and (privkey2,pubkey2) and linking between them, e.g. by signing with privkey1 a message that says that pubkey2 is the public key of your 2nd pair, and from then on you can start using privkey2 to provide the PoS signatures.

What it would mean for the blockchain is that when you provide a STAKEMSG, there would be an additional field that you can include in it, and this field would contain pubkey2, meaning that starting from the next checkpoint block you are allowed to use privkey2 in order to provide signatures for the address that's controlled by privkey1.

<s>The protocol rule would be that only first pubkey2 that the stakeholder provides is respected, meaning the nodes should start scanning at POSGEN for the first STAKEMSG that linked pubkey2 to pubkey1 (DoS attacks?), and then deduce how many bitcoins pubkey1 controls. Maybe the client should cache this data (security risk?).</s>

The pubkey that would be extracted from subsequent STAKEMSGs is pubkey2 rather than pubkey1, therefore in order to tell how many bitcoins are controlled by those STAKEMSGs we store in every STAKEMSG an additional field that specifies the height of B->count relative to the block in which pubkey1 and pubkey2 were linked (and then the protocol rule would be that only this particular linkage should be respected). If we use e.g. 3 bytes for the relative height field, then privkey1 will be needed to create a new linkage block after about 320 years (assuming 10min blocks).

Note: if the pubkey2 field of STAKEMSG is empty then the signature field of STAKEMSG signed just B->hash, and if the pubkey2 field of STAKEMSG isn't empty then the signature field of STAKEMSG signed "B->hash + pubkey2".

With ECDSA signatures are 512 bits and compressed pubkeys are 258 bits, so it's not so bad because the STAKEMSGs with the extra pubkey2 field would be infrequent. In fact, we can save more space by defining the protocol so that only hash(pubkey2) is put in the extra field, because of the feature of ECDSA that you can extract pubkeys from signatures. This means that the extra field can be just (say) 128 bits hash, but more computing power will be needed to verify the signatures blocks.

This means that you wouldn't need to enter your passphrase in order to provide PoS signatures, so that the client app can work automatically, as preferred.

=== Security from attacker that denies txns ===

Note: this is unrelated to proof-of-stake?

Motivation: while proof-of-stake provides stronger security from double-spending attacks, an attacker with 51% hashpower (and without any stake) can still attack the network by generating empty blocks, thereby denying everyone from transacting. If the attacker releases his branch at certain intervals before the signatures block, then the competing branch by the rest of the distributed hashpower might have never been created because the miners would try to extend the attacker's branch, which means that the stakeholders would only have a single branch to sign. Suppose that we have simple protocol rule that requires at least one txn in every block, if there aren't any txns during some time period then that's ok because there wouldn't be a need to generate a new block then, but still this simple rule isn't helpful because the attacker can just transfer some coins to himself in the blocks of his secret branch. What we really want is [[Bitcoin Days Destroyed|BDD]], meaning that after the attacker spends his coins in the block that he generated, he cannot use those coins again.

Protocol rule: we require that the total BDD weight of one of the last (say) 10 block is at least (say) 20% of the average BDD weight of blocks in the last day, or else we require the difficulty of the 10th block to correspond to twice as much time (this is the basic idea, a version with more continuous parameters could be better). This means that if an attacker tries to deny most/all txns, he will have to generate some 20min blocks, while the rest of the distributed hashpower only needs to generate 10min blocks, so the attacker has a significant disadvantage as he tries to compete with the honest hashpower.

One drawback is that during a 'slow day' without many txns, the performance of the network could degrade to 20min blocks at certain time periods, even though it isn't being attacked at all.

Problem: if it's a slow day on the real network, then an attacker could prepare a branch that outcompetes the distributed network, because if he spends old coins in his branch then he will need less difficulty.

=== Conclusion ===

Proof of Stake proposals attempt to address 3 major issue:

(1) Better security from double-spending attacks

(2) Better security from denial-of-txns attacks

(3) Being more energy-efficient than PoW

This design outline claims to address (1) and (2) in the sense that it provides better security without introducing new risks. It doesn't attempt to address (3) directly, but the added security that proof-of-stake provides may result in less need for PoW hashpower.

=== Proof of Stake idea1 (by coblee) ===

Instead of including in the blockchain all the signatures that the stakeholder provide, we only include a single winning signature. The stakeholders try to sign the block hash with their privkeys, and we then hash each such signature and get its current hash-weight (the smaller hash-weight the better). The winning privkey is the one with the biggest coins-held/hash-weight value (maybe more sophisticated calculation instead of this division). Assuming that the hash function is random, this calculation should imply that an address that holds 2N coins is twice as likely to win compared to an address that holds N coins.

Unclear: all blocks should be signed by stakeholders, or only checkpoint blocks in order to allow better network propagation etc.

The protocol rule is that the branch with the biggest function(difficulty, signatures) wins. If an attacker who holds N coins tries to compete with the distributed network that holds M coins, and we assume M>N, then the distributed network holds more stake and is therefore more likely to generate signatures with better weights, thereby creating a branch that outcompetes the attacker's branch.

The benefits of this idea are: less blockchain bloat, and less network communication because nodes shouldn't propagate the non-winning signature if they're already aware of another signature that outcompeted it.

Problem: if each wallet tries to sign with all of its privkeys, then we wouldn't want to establish linkages in the blockchain between all of its signing-pubkeys with its normal-pubkeys. 
Possible solution: deterministic wallet, so when your signature wins you include in the txn a field that specifies its idx in the deterministic wallet, i.e. if the linkage is between pubkey1 and pubkey2, then the pubkey that corrensponds to the privkey that signed is hash(pubkey2|idx) and all the nodes can verify it.

=== Proof of Stake idea2 (by coblee) ===

99% of the reward of each block goes to the miner, and 1% of the reward is given to a pseudorandom address.

The pseudorandom address is selected deterministically as a function of the block hash, so that an address that holds more coins is more likely to be selected, as follows: we use to block hash to get a random index of 1 satoshi among all the satoshis that have been produced so far, and follow the txns in which this satoshi moved, until we reach an unspent txn, so the address that controls this satoshi is selected. This means that if one person holds 200 coins in several addresses, and another person holds 100 coins in several addresses, then it is twice as likely that one of the addresses of the first person will be selected.

Then in the next (say) 120 blocks, the stakeholder who received that 1% of the reward should spend it, and thereby provide proof of stake for the branch. The branch with higher function(difficulty, proof-of-stake) wins. If the winning address didn't spend the coins within 120 blocks, then it loses them. An attacker who tries to prepare a forked branch cannot spend these 1% coins because he doesn't control the privkeys of these addresses.

Benefits: having encrypted wallet with passphrase could be OK, only when your address is selected you need to access your privkey, and there's a certain time interval in which you may do it. No need for nodes to propagate the winning signature, as in idea1.

Variation: stakeholders lose a little (e.g. 0.5 coins) if they don't provide proof-of-stake, and keep their entire stake otherwise. The address that was selected should do a txn that references the block in which it was selected, and is otherwise required to keep holding at least 0.5 coins in the next 120 blocks (or less than 0.5 if it had less when it was selected). If within 120 blocks it doesn't do the txn that references the block that it was supposed to provide proof-of-stake for, then it loses 0.5 coins (or less if it had less).

Irreversible Transactions

2012-12-04T17:46:12Z

Holy-Fire: /* Attack vectors */ Corrected >50% confusion

Double-spending is the result of successfully spending some money more than once. Bitcoin protects against double spending by verifying each transaction added to the [[block chain]] to ensure that the inputs for the transaction had not previously already been spent.

Other electronic systems prevent double-spending by having a master authoritative source that follows business rules for authorizing each transaction. Bitcoin uses a decentralized system, where a consensus among nodes following the same protocol is substituted for a central authority.

Bitcoin has some exposure to fraudulent double-spending when a transaction is first made, with less and less risk as a transaction gains [[confirmation|confirmations]].

==Attack vectors==

===Race attack===

Traders and merchants who accept a payment immediately on seeing "0/unconfirmed" are exposed to a double-spend occurring is there was a fraudulent attempt that successfully communicated one transaction to the merchant yet communicated a different transaction that spends the same coin that was first to eventually make it into the block chain.

Merchants can take precautions (e.g., disable incoming connections, only connect to well connected nodes) to lessen the risk of a race attack but the risk cannot be eliminated. Therefore, the cost/benefit of the risk needs to be considered when accepting payment on 0/unconfirmed when there is no recourse against the attacker.

The [[research]] paper [http://eprint.iacr.org/2012/248.pdf Two Bitcoins at the Price of One] finds that the protocol allows a high degree of success by an attacker in performing race attacks. The method studied in the research paper depends on access to the merchant's Bitcoin node which is why that even prior to this paper, recommendations for merchants include disabling incoming connections and to choose specific outgoing connections<ref>[http://bitcointalk.org/index.php?topic=79090.msg881283#msg881283 BitcoinTalk Thread - Two Bitcoins at the Price of One]</ref>.

===Finney attack===

Another attack the trader or merchant is exposed to when accepting payment on 0/unconfirmed. The Finney attack is a fraudulent double-spend that requires the participation of a miner once a block has been mined<ref>[http://www.bitcointalk.org/index.php?topic=3441.msg48384#msg48384 Best practice for fast transaction acceptance - how high is the risk?]</ref>. The risk of a Finney attack cannot be eliminated regardless of the precautions taken by the merchant, but the participation of a miner is required and a specific sequence of events must occur. Thus the attack is not trivial nor inexpensive to perform and only makes sense for the attacker when the gains from the attack are significant. Just like with the race attack, a trader or merchant should consider the cost / benefit when accepting payment on just one confirmation when there is no recourse against the attacker.

===Vector76 attack===

Also referred to as a one-confirmation attack, is a combination of the race attack and the Finney attack such that a transaction that even has one confirmation can still be double-spent. The same protective action for the race attack (no incoming connections, explicit outgoing connection to a well-connected node) significantly reduces the risk of this occurring.

===Brute force attack===

This attack has a chance to work even if the merchant waits for some confirmations, but requires relatively high hashrate.

The attacker submits to the merchant/network a transaction which pays the merchant, while privately mining a blockchain fork in which a double-spending transaction is included instead. After waiting for ''n'' confirmations, the merchant sends the product. If the attacker happened to find more than ''n'' blocks at this point, he releases his fork and regains his coins; otherwise, he can try to continue extending his fork with the hope of being able to catch up with the network. If he never manages to do this, the attack fails and the payment to the merchant will go through.

The probability of success is a function of the attacker's hashrate (as a proportion of the total network hashrate) and the number of confirmations the merchant waits for. For example, if the attacker controls 10% of the network hashrate but the merchant waits for 6 confirmations, the success probability is on the order of 0.1%.

===>50% attack===

If the attacker controls more than half of the network hashrate, the previous attack has a probability of 100% to succeed. Since the attacker can generate blocks faster than the rest of the network, he can simply persevere with his private fork until it becomes longer than the branch built by the honest network, from whatever disadvantage.

No amount of confirmations can prevent this attack; however, waiting for confirmations does increase the aggregate resource cost of performing the attack, which could make it unprofitable or delay it long enough for the circumstances to change or slower-acting synchronization methods to kick in.

==Risk management==

There are third-party services to assist traders and merchants to help manage the risk or to insure against losses.

==See Also==

* [[Weaknesses]]
* [[How bitcoin works]]
* [http://codinginmysleep.com/bitcoin-attacks-in-plain-english Bitcoin Attacks in Plain English] by David Perry

==References==
<references />

[[Category:Technical]]

IRC channels

2012-04-15T14:01:40Z

Holy-Fire: + #bitcoin-il

Most of the following Bitcoin-related IRC channels are available on [http://www.freenode.net Freenode]:

==Bitcoin Project==
{| class="wikitable"
! Channel !! Description
|-
| {{Freenode IRC|bitcoin}} || General Bitcoin-related discussion. ([http://bitcoinstats.com/irc/bitcoin/logs/ history])
|-
| {{Freenode IRC|bitcoin-dev}} || Bitcoin software development. ([http://bitcoinstats.com/irc/bitcoin-dev/logs/ history])
|-
| {{Freenode IRC|bitcoin-politics}} || Discuss politics with other Bitcoin users.
|-
| {{Freenode IRC|bitcoin-gaming}} || Bitcoin gamers hangout.
|-
| {{Freenode IRC|bc-news}} || RSS News related to Bitcoin.
|-
| {{Freenode IRC|bitcoin-marketing}} || Marketing and promotion of bitcoin
|-
| {{Freenode IRC|bitcoin-gentoo}} || Gentoo community.
|-
| {{Freenode IRC|bitcoin-watch|text=[[Bitcoin-Watch|#bitcoin-watch]]}} || Streaming Bitcoin transactions, including market data.
|-
| {{Freenode IRC|bitcoin-bots}} || Bot and bot-related discussion; trading bots, IRC bots, utility bots.
|-
| {{Freenode IRC|bitcoin-police}} || [[Bitcoin Police]] Investigates incidents related to Bitcoin.
|-
| {{Freenode IRC|bitcoin-court}} || [[Bitcoin Court]] Settles disputes between parties.
|-
| {{Freenode IRC|bitcoin-tweets}} || Automated announce of bitcoin-related tweets.
|-
| {{Freenode IRC|bitcoin-church}} || [[Bitcoin Church]] Discussion of our savior Satoshi
|}

===Local communities===

{| class="wikitable"
| {{Freenode IRC|bitcoin-otc-eu}} || European OTC trading marketplace.
|-
| {{Freenode IRC|bitcoin-otc-uk}} ||United kingdom OTC Trading Marketplace.Founder Angus Bates.
|-
| {{Freenode IRC|bitcoin-otc-ru}} || Russian OTC trading marketplace.
|-
| {{Freenode IRC|btc.chat}} || Russian bitcoin community.
|-
| {{Freenode IRC|bitcoin-aus}} || Aussie bitcoin community.
|-
| {{Freenode IRC|bitcoin-br}} || Brazilian bitcoin community.
|-
| {{Freenode IRC|bitcoin-cad}} || Canadian bitcoin community.
|-
| {{Freenode IRC|bitcoin-cn}} || Chinese bitcoin community.
|-
| {{Freenode IRC|bitcoin-de}} || German bitcoin community.
|-
| {{Freenode IRC|bitcoin-il}} || Israeli bitcoin community.
|}

==Mining Related Communities==

{| class="wikitable"
! Channel !! Description
|-
| {{Freenode IRC|bitcoin-mining}} || Discussion and support related to mining.
|-
| {{Freenode IRC|bitcoin-fpga}} || Discussion and support specific to FPGA mining.
|-
| {{Freenode IRC|btc.chat.miners}} || Russian discussion of mining specification.
|-
| {{Freenode IRC|eligius}} || [[Eligius]] mining pool community
|-
| {{Freenode IRC|ozcoin}} || [[Ozco.in]] mining pool community
|-
| [irc://irc.foonetic.net/xkcd-bitcoin IRC] [http://irc.lc/foonetic/xkcd-bitcoin/Miner@@@ Web] #xkcd-bitcoin || [https://en.bitcoin.it/wiki/XKCD_Pool XKCD Pool]
|-
| [irc://irc.quakenet.org/bitcoins.lc IRC] [http://irc.lc/quakenet/bitcoins.lc/Miner@@@ Web] #bitcoins.lc @ Quakenet || [http://www.bitcoins.lc Bitcoins.lc Pool]
|-
| {{Freenode IRC|bithasher}} || Bit Pool Mining
|-
| {{Freenode IRC|p2pool}} || [[P2Pool]] decentralized mining pool
|-
| {{Freenode IRC|btcserv}} || [[Btcserv.net]] Mining Pool Community
|-
| {{Freenode IRC|bitminter}} || [[BitMinter]] Mining Pool Community
|}

==Communities for Exchanges and Trading==

{| class="wikitable"
! Channel !! Description
|-
|-
| {{Freenode IRC|bitcoin-auction}} || Live auctions over IRC.
|-
| {{Freenode IRC|bitcoin-market}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-aud}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-bgn}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-brl}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-cad}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-chf}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-eur}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-gbp}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-hkd}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-inr}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-jpy}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-nzd}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-pln}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-rub}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-sek}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-sgd}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-sll}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-thb}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-usd}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-markets-zar}} || Streaming market data (only), no chat.
|-
| {{Freenode IRC|bitcoin-otc|text=[[bitcoin-otc|#bitcoin-otc]]}} || Over-the-counter trading marketplace and discussion. ([http://bitcoinstats.com/irc/bitcoin-otc/logs/ history])
|-
| {{Freenode IRC|bitcoin-escrow}} || Third party escrow agents.
|-
| {{Freenode IRC|bitcoin-otc-ticker|bitcoin-otc-ticker}} || Streaming market data form the [[#bitcoin-otc]] order book.
|-
| {{Freenode IRC|bitcoin-pit}} || Only over-the-counter trading.
|-
| {{Freenode IRC|bitcoin-tickers}} || Bitcoin tickers for all bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-aud}} || Bitcoin tickers for AUD bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-bgn}} || Bitcoin tickers for BGN bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-brl}} || Bitcoin tickers for BRL bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-cad}} || Bitcoin tickers for CAD bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-chf}} || Bitcoin tickers for CHF bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-eur}} || Bitcoin tickers for EUR bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-gbp}} || Bitcoin tickers for GBP bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-hkd}} || Bitcoin tickers for HKD bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-inr}} || Bitcoin tickers for INR bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-jpy}} || Bitcoin tickers for JPY bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-nzd}} || Bitcoin tickers for NZD bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-pln}} || Bitcoin tickers for PLN bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-rub}} || Bitcoin tickers for RUB bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-sek}} || Bitcoin tickers for SEK bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-sgd}} || Bitcoin tickers for SGD bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-sll}} || Bitcoin tickers for SLL bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-thb}} || Bitcoin tickers for THB bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-usd}} || Bitcoin tickers for USD bitcoin markets
|-
| {{Freenode IRC|bitcoin-tickers-zar}} || Bitcoin tickers for ZAR bitcoin markets
|-
| {{Freenode IRC|bitcoin-wot|bitcoin-wot}} || Distributed Web of Trust (WoT) system for [[#bitcoin-otc]].
|-
| {{Freenode IRC|btc.chat.traders}} || Russian community discussion about trades/exchanges.
|-
| {{Freenode IRC|bitcoinconsultancy}} || [[Bitcoin Consultancy]] discussion
|-
| {{Freenode IRC|#mtgox-chat}} || [[#MtGox]] chat (Note the pound sign (#) is part of the channel name)
|-
| {{Freenode IRC|mtgox}} || [[MtGox]] support
|-
| {{Freenode IRC|mtgoxlive}} || [[MtGox Live]] real-time view of trading
|-
| {{Freenode IRC|mtgox-news}} || Mt. Gox topics from Twitter.
|}

==Related Communities==

{| class="wikitable"
! Channel !! Description
|-
| {{Freenode IRC|namecoin}} || [[Namecoin]] and the [[Dot-bit]] project.
|-
| {{Freenode IRC|bitcoin-stackexchange}} || Discussion complementing [http://bitcoin.stackexchange.com Bitcoin StackExchange].
|-
| {{Freenode IRC|witcoin}} || [[Witcoin]] social news and user generated content.
|}

[[pl:Kanały IRC]]

Bitcoin Wiki:Community portal

2012-04-15T14:00:30Z

Holy-Fire: + bitcoin.org.il

== Bitcoin Community Forums on various platforms ==

* [http://www.reddit.com/r/Bitcoin/ /r/Bitcoin]
* [http://AnonCoin.org AnonCoin.org]five
* [http://forums.somethingawful.com/showthread.php?threadid=3413928 Bitcoin on SomethingAwful]
* [http://forum.bitcoin.com.au/ Bitcoin Australia Forum]
* [http://www.bitcoin-board.com/ Bitcoin-Board Forum]
* [http://bitcoin.org.uk/forums Bitcoin Forums]
* [http://www.bitcoinforums.net BitcoinForums.Net]
* [http://groups.google.com/group/bitcoin-discussion Bitcoin google group]
* [http://bitcoinitalia.com/forum/ Bitcoin Italia ]
* [http://goo.gl/2PncY Bitcoin Portal p2p (on Osiris platform)]
* [https://bitcoinscene.org/forum.php Bitcoin Scene]
* [http://bitcoin.stackexchange.com/ The Bitcoin StackExchange]
* [http://bit-coin-trading.com/forum/index.php Bitcoin Trading Forum]
* [http://bitcointalk.org/ Bitcointalk]
* [http://bitforums.net/ BitForums.net Forum]
* [http://www.btclog.com btc::log]
* [http://forum.guildminers.com/ Guildminers Forum]
* [http://forum.mtgoxlive.com/ MtGox Live Traders Forum]
* [http://bitcoin.pl/forum/ Polish Bitcoin community forum]
* [http://rubitcoin.com/ Russian bitcoin community forum]
* [http://steamcommunity.com/groups/bitcoin Steam Community for Bitcoin]
* [http://tweetforum.com/bitcoin TweetForum Bitcoin Community]

== Bitcoin Community Groups on Bitcoin Wiki platform ==

=== Special interests ===
* [[Bitcoin Wiki]]-group

=== Geographically ===
* [[Espagna]] / [[Spain]] (E.)
* [[France]] / [[France]] (F.)
* [[Germany]] / [[Deutschland]] (D.)
* [[Netherlands]] (NL) and [[Belgium]] (B.)
* [[United Kingdom]] of Great Brittain (GB) and Northern Ireland
* [[United States]] of America (USA)

== IRC Chat ==

* See [[IRC_channels|IRC channels]]

==Wiki Users==

* [http://en.bitcoin.it/wiki/Special:ListUsers List of Users] registered on the Bitcoin wiki.

== Events ==

* [[Meetups]]
* [http://www.bitcoin.org/smf/index.php?topic=4526.0 Events, conferences and other events]

==Bitcoin Related Publications==

* [[Bitcoin Weekly]] weekly newspaper by [[User:Kiba|Kiba]]
* [[Bitcoin Sun|The Bitcoin Sun]] weekly newspaper
* See [[:Category:Blogs|Blogs]] category
* See [[Press]]

== Maps ==
* [[Bitcoin.local]] Local exchanges
* The [[Bitcoin Map (Collaborative map)|Bitcoin Map]] collaborative map
* [[Bitcoin Users Worldwide]] - Find nearby Bitcoin users • Engage in local trade • Add your own offers • Get notifications

== Monitoring ==
* [http://bitcoincharts.com/markets/ Bitcoin Charts] displays an overview of Bitcoin exchange markets.
* The [http://www.bitcoinmonitor.com/ Bitcoin Monitor] visualizes transactions, new blocks and trades on markets as they are happening.
* [http://www.bitcoinwatch.com/ Bitcoin Watch] has various statistics on things like the size of the economy or the number of transactions.

== Bitcoin Project ==
* [http://www.bitcoin.org Bitcoin.org] Official project site
* [[:Category:Developer|Developer]] pages
* [[Bitcoin Standards Organization]]

== External Communities ==

* [http://steamcommunity.com/groups/bitcoin Bitcoin Group on Steam] platform by Valve

* [http://www.bitcoinitalia.com Bitcoinitalia.com] Italian news Bitcoin portal

* [http://btcsec.com/ BTCsec.com] Russian website about Bitcoin

* [http://bitcoin.org.il/ bitcoin.org.il] Israel Bitcoin community homepage

Proof of Stake

2012-03-19T10:08:28Z

Holy-Fire: + Meni's system

Proof of Stake is a proposed alternative to [[Proof of Work]]. Like proof of work, proof of stake provides a mechanism for determining who signs bitcoin transactions.

It was probablly first proposed [https://bitcointalk.org/index.php?topic=27787.0 here] by Quantum Mechanic. With Proof of Work, the probability of mining a block depends on the work done by the miner (e.g. CPU/GPU cycles spent checking hashes). With Proof of Stake, the resource that's compared is the amount of Bitcoin a miner holds - someone holding 1% of the Bitcoin can mine 1% of the "Proof of Stake blocks".

Some argue that methods based on Proof of Work alone might lead to a low network security due to [[Tragedy of the Commons]], and Proof of Stake is one way of changing the miner's incentives in favor of higher network security.

Here is [https://bitcointalk.org/index.php?topic=37194.msg456773#msg456773 one attempt] to describe an implementation of Proof of Stake.

= Motivation For Proof of Stake =

* A proof-of-stake system might provide increased protection from a malicious attack on the network. Additional protection comes from two sources:
1) Executing an attack would be much more expensive.
2) Reduced incentives for attack. The attacker would need to own a near majority of all bitcoin. Therefore, the attacker suffer severely from his own attack.

* When block rewards are produced through txn fees, a proof of stake system would result in lower equilibrium txn fees. Lower long-run fees would increase the competiveness of bitcoin relative to alternative payments systems. Intuitively reduced fees are do to vast reductions in the scale of wastage of resources.
== The Monopoly Problem ==

If a single entity (hereafter a monopolist) took control of the majority of txn verification resources, he could use these resources to impose conditions on the rest of the network. Potentially, the monopolist could choose to do this in malicious ways, such as double spending or denying service. If the monopolist chose a malicious strategy and maintained his control for a long period, confidence in bitcoin would be undermined and bitcoin purchasing power would collapse. Alternatively, the monopolist could choose to act benevolently. A benevolent monopolist would exclude all other txn verifiers from fee collection and currency generation, but would not try to exploit currency holders in any way. In order to maintain a good reputation, he would refrain from double spends and maintain service provision. In this case, confidence in Bitcoin could be maintained under monopoly since all of its basic functionality would not be affected.

Both benevolent and malevolent monopoly are potentially profitable, so there are reasons to suspect that an entrepreneurial miner might attempt to become a monopolist at some point. Due to the [[Tragedy of the Commons]] effect, attempts at monopoly become increasingly likely over time.

== How Proof of Stake Addresses Monopoly Problems ==

Monopoly is still possible under proof-of-stake. However, proof-of-stake would be more secure against malicious attacks for two reasons.

Firstly, proof-of-stake makes establishing a verification monopoly more difficult. At the time of writing, an entrepreneur could achieve monopoly over proof-of-work by investing at most 10 million USD in computing hardware. The actual investment necessary might be less than this because other miners will exit as difficulty increases, but it is difficult to predict exactly how much exit will occur. If price remained constant in the face of extremely large purchases (unlikely), such an entrepreneur would need to invest at least 20 million USD to obtain monopoly under proof-of-stake. Since such a large purchase would dramatically increase bitcoin price, the entrepreneur would likely need to invest several times this amount. Thus, even now proof-of-stake monopoly would be several-fold more costly to achieve than proof-of-work monopoly. Over time the comparison of monopoly costs will become more and more dramatic. The ratio of bitcoin's mining rewards to market value is programmed to decline exponentially. As this happens, proof-of-work monopoly will become easier and easier to obtain, whereas obtaining proof-of-stake monopoly will become progressively more difficult as more of the total money supply is released into circulation.

Secondly, and perhaps more importantly, a proof-of-stake monopolist is more likely to behave benevolently exactly because of his stake in Bitcoin. In a benevolent monopoly, the currency txn continue as usual, but the monopolist earns all txn fees and coin generations. Other txn verifiers are shut out of the system, however. Since mining is not source of demand for bitcoin, bitcoin might retain most of its value in the event of a benevolent attack. Earnings from a benevolent attack are similar regardless of whether the attack occurs under proof-of-stake or proof-of-work. In a malicious attack, the attacker has some outside opportunity which allows profit from bitcoin's destruction (simple double-spends are not a plausible motivation; ownership of a competing payment platform is). At the same time, the attacker faces costs related to losses on bitcoin-specific investments which are necessary for the attack. It can be assumed that a malicious attack causes the purchasing power of bitcoin to fall to zero. Under such an attack, the proof-of-stake monopolist will lose his entire investment. By contrast, a malicious proof-of-work monopolist will be able to recover much of their hardware investment through resale. Recall also, that the necessary proof-of-work investment is much smaller than the proof-of-stake investment. Thus, the costs of a malicious attack are several-fold lower under proof-of-work. The low costs associated with malicious attack make a malicious attack more likely to occur.

== Why Proof of Stake Would Likely Decrease Long-run Txn Fees Considerably ==
In a competitive market equilibrium, the total volume of txn fees must be equal to opportunity cost of all resources used to verify txns. Under proof-of-work mining, opportunity cost can be calculated as the total sum spent on mining electricity, mining equipment depreciation, mining labor, and a market rate of return on mining capital. Electricity costs, returns on mining equipment, and equipment depreciation costs are likely to dominate here. If these costs are not substantial, then it will be exceptionally easy to monopolize the mining network. The fees necessary to prevent monopolization will be onerous, possibly in excess of the 3% fee currently charged for credit card purchases. Under pure proof-of-stake, opportunity cost can be calculated as the total sum spent on mining labor and the market interest rate for risk-free bitcoin lending (hardware-related costs will be negligible). Since bitcoins are designed to appreciate over time due to hard-coded supply limitations, interest rates on risk-free bitcoin-denominated loans are likely to be negligible. Therefore, the total volume of txn fees under pure proof-of-stake will just need to be just sufficient to compensate labor involved in maintaining bandwidth and storage space. The associated txn fees will be exceptionally low. Despite these exceptionally low fees, a proof-of-stake network will be many times more costly to exploit than the proof-of-work network. Approximately, a proof-of-work network can be exploited using expenditure equal to about one years worth of currency generation and txn fees. By constrast, exploitation of a proof-of-stake network requires purchase of a majority or near majority of all extant coins.

= Implementations =
There are currently at least two distinct proposals on how to implement PoS, by Cunicula and Meni.

== Cunicula's Implementation of Mixed Proof-of-Work and Proof-of-Stake ==

This suggestion is of a mixed Proof-of-Work / Proof-of-Stake system.

=== Definitions ===
'Coin-confirmations' are defined as the product of the number of coins in an account multiplied by the number of confirmations on this account.

'Confirmations' are defined as the number of blocks mined since this account's private key was last used to send coins or sign a newly mined block.

=== How the system works ===
Each block must be signed by its miner using a single bitcoin account. The account used to sign a block must also be the recipient of txn fees and generation from this block. Blocks are mined by proof-of-work hashing as before, but with modified difficulty criteria. The difficulty criterion for block validity is modified as follows:

Hash generates valid block if and only if

Hash Difficulty >= Difficulty Target / ( max(Coin-confirmations used to sign block, 100 satoshi-confirmations) )^( p / (1-p))

, where 0 <= p < 1. Stake becomes more and more important as p approaches 1. p=0.8 is suggested as an appropriate choice. p=0 is identical to the current proof-of-work system.

If the block is signed by a bitcoin account holding less than 100 satoshi-confirmations, this is treated as if the account held 100 satoshi-confirmations. Thus non-stakeholders are allowed to verify blocks, but relative to stakeholders they must meet extremely stringent difficulty criteria. Permitting non-stakeholders to verify blocks solves the initial distribution problem.

As before the Difficulty Target is a periodically adjusted constant which is set to maintain a target generation rate of 1 block every 10 minutes.

=== Does this system exhibit Constant-Returns-to-Scale ? ===

While the formal theory behind this has yet to be laid out in detail, simulations indicate that the system is fully described by a constant returns-to-scale Cobb-Douglas production function. Generation rate over a long time span is almost perfectly predicted by the following equation, where Q is generation per unit time, k is the number of coins invested in generation, h is hashing power, A is an arbitrary constant which is inversely proportional to difficulty, and p is the parameter described in the previous section.

Q = A*k^(p)*h^(1-p)

=== How could we see constant returns to scale here? ===

Returns-to-scale in this system are subtle. If you double hashing power at one point in time, then you double the probability that you will find a block in the current hashing round. Therefore, intuitively one might think that doubling hashing power would allow you to generate double the amount of bitcoin generated per unit time on average. However, this is not true. Outcomes in each round of hashing affect outcomes in subsequent rounds of hashing. In this system, failure to find a block in the current period leads to decreased expected waiting time in the next round (since if you fail in the current round you get the consolation prize that the next round will have an easier target). This decrease in future waiting time provides some compensation for not mining the block immediately. Thus, doubling your chance of mining the block immediately does not double your output over a longer period.

=== Stylized Example (You get an outcome that works like this when p is close to 1) ===

Consider a system where:
you have a 0% chance of mining coins at less than 6 coin confirmations,
a 50% chance of mining coins at 6 coin confirmations,
and a 100% chance of mining coins at 7 or more coin confirmations.

Half the time you will mine your coin after 6 confirmations. The other half you will mine your coin after 7. Therefore, it will take 6.5 rounds on average to mine a block.

Now what if you double hashing power. Remember that this doubles your chance of mining a block at any given stage. Now..
you have a 0% chance of mining coins at less than 6 coin confirmations,
a 100% chance of mining coins at 6 or more coin confirmations,

Therefore, it will take 6 rounds on average to mine a block.

Here you have doubled hashing power, but only increased average output per unit time by a small amount.
=== Infeasibility of Pure Proof of Stake Under this System ===
Note: in the limit when p -> 1 (that is p approaches pure proof of stake), you approach a situation where you have a 0% chance of mining coins at less than x coin confirmations, but a 100% chance at x+1 coin confirmations, where x depends soley on difficulty. Mining becomes completely deterministic and doubling hashing power has no effect on output at all. Essentially miners take turns to mine blocks. The frequency with which a miner's turn comes up is equal to his ownership share in the total volume of coins actively used for mining. This sounds really good, but a fatal problem arises if participation falls. A fall in participation would make it impossible for anyone to mine blocks. Particularly, worrisome is that if participation is at 100%, a loss of some coins would interrupt the blockchain forever with no possible remedy except location of the missing coins. Even without a loss of coins, simply transferring coins across wallets can disrupt turn-taking and freeze the blockchain forever. For these reasons, it is necessary for block mining to retain a random element and not follow a deterministic, pure proof of stake system, i.e. p can safely be 0.8 or 0.9 or even 0.99, but 0.9999999999999999 would make complete failure of the blockchain a certainty.

== Meni's implementation ==
This proposal is for a proof-of-work (PoW) skeleton on which occasional checkpoints set by stakeholders are placed. In one variant, double-spending is prevented by waiting for a transaction to be included in a checkpoint; the variant described here uses cementing to prevent double-spending, and checkpoints to resolve cementing conflicts.

=== Proof of work ===
Miners use their hashrate to find blocks and build the blockchain exactly as with the pure PoW system. They receive any new generated coins from the block; there will be two kinds of transaction fees, one of which is a mining fee given to the miner who finds the block, just like the PoW transaction fees.

=== Signatures ===
One block every 100 blocks (a different number can be used instead) is a signature block. When a signature block is found and confirmed with several subsequent blocks, stakeholders (people who have bitcoins) are expected to sign it by using a private key associated with their address which contains coins to sign the block hash. If there are several blocks of the same height, an address should not sign more than one of them. The signatures are broadcast on the network and included in a future block. For every candidate block, the total weight of all signatures is tallied (the weight of an address is determined mostly by the number of coins in it, as of the last signature block). Stakeholders will be able to collect signature fees when providing a signature, proportionally to their weight.

At the basic level, there are no rules to choosing which of several conflicting blocks to sign, stakeholders should just choose one.

=== Cementing ===
Cementing is a node's reluctance to do a blockchain reorganization. A node will reject any new block found if it contradicts a 6-block deep branch it is already aware of and currently considers valid. That is, once a node receives 6 confirmations for a block, it will not accept a competing block even if it is part of a longer branch.

In a pure PoW system this is problematic to do because a node could be stuck on "the wrong version" - if an attacker isolates the node and feeds him bogus data, it will not embrace the true, longer chain when he learns of it. However, using PoS to have the final say in such situations makes this possible.

=== Branch selection ===
When a node needs to select which of several branches is valid, it chooses one based on the following criteria in increasing importance (each one is overridden by the next):

#Branch length (total difficulty of all blocks), as in a PoW system.
#Cementing - an already cemented block will not be replaced by a longer branch.
#Signatures - even a cemented block will be overridden by a signature block with signature weight more than half the total possible weight by some margin.

If the conflict is so long that it contains more than one spot for a signature block, the conflicting signature blocks will be traversed earliest to latest, each time choosing the branch with the majority vote. After the newest uncontested signature block it proceeds to use cementing and branch length.

A signature block with no clear majority will be considered tied, and will not override the other criteria. Signature fees will not be given out but instead carried over to the next signature spot, to encourage stakeholders to participate then.

=== Double spending prevention ===
A good level of security can be achieved by waiting for a block to be cemented. By that time it is safe to assume that the network recognizes this block and will not easily switch to a different block, even if a longer branch is presented.

A more authoritative confirmation is enabled by waiting for a signature block. Once a block achieves a majority (and some more time is allowed for this majority to spread in the network), it is extremely unlikely that the network will ever switch away from this block.

=== Weights ===
The weight of every address starts at 0. When an address provides a signature, its weight increases so that after several signatures, the weight approaches the number of coins in the address as of the last signature block. For example,
New weight = 0.9 * Old weight + 0.1 * Balance
If a signature is not provided by the address in a signature block, its weight decreases:
New weight = 0.9 * Old weight
This way, addresses whose owners do not wish to participate in signing do not hamper the ability to reach a majority.

If an address signs two conflicting blocks, its weight is reset to 0. This is to limit the power of malicious stakeholders.

If coins move to a new address, weight is proportionally taken away from the addressed, but is not transferred to the new address. The new stakeholder will have to build up his weight.

=== Malicious stakeholders ===
The system is resilient against stakeholders who misuse their signature power, even if they have a majority of the bitcoins. Since their only obligation is to not sign conflicting blocks, the only way they could double-spend is if they first sign one block so it achieves a majority, then sign a different one so that it achieves a bigger majority. Generally this will not work. A short while after a majority is achieved, most of the network will be aware of the relevant signatures. If a different signature is broadcast, the conflict will be detected and both signatures will be ignored. This will cause the current majority block to become tied, but the network is already cemented on it and will vote for this branch in the next signature block. The weight of the attacker will by then reduce to 0 so he will be unable to create more disruption.

Another attack is refusing to sign blocks to keep them tied. Since this causes a decay of the weight, they can only stand in the way of a majority for a short time.

=== Denial of service ===
The method as described does not solve a denial of service scenario. A majority miner could create only blocks with no transactions (or with many transactions missing) and reject all other blocks.

This may be solvable by adding some measure of the transaction in a block to the selection criteria, such as Bitcoin days destroyed.

Also, proposals to replace the block chain with a directed acyclic graph have been made, and could be used to make it easier to include transactions.

== Key difference between the two proposals ==
In Cunicula's system, voting power is determined by combining (multiplicatively) your hashrate and stake. This would be problematic if small players could not compete effectively with large players. Though we are waiting on a formal mathematical proof, evidence to date suggests that small and large players would have an equal competitive footing. Simulations described in this thread [https://bitcointalk.org/index.php?topic=68213.msg801253#msg801253] indicate that small players are competitive with large players because the multiplicative combination of hashrate and stake exhibits constant returns. Evidence in the thread suggests that these simulation results are accepted by both Cunicula and Meni.)

In Meni's, there's a skeleton based purely on hashrate, and superimposed on it are occasional checkpoints set by stakeholders. You can contribute PoW without having stake, and you can contribute PoS without having work, and in both cases your voting power and reward is linearly proportional to the resources you have.

[[category:mining]]

List of address prefixes

2012-02-19T10:37:04Z

Holy-Fire: sort, typo

Blockchain-based currencies use addresses, which are a [[Base58Check encoding]] of some hash, typically that of a public key. The encoding includes a version byte, which affects the first character in the address. The following is a list of some prefixes which are in use.

{| class="wikitable"
|-
!Decimal version
!Leading symbol
!Use
!Example
|-
|0
|1
|Bitcoin pubkey hash
|12CPLrAUPvhVwjZqBgww3sLdEg4Z888R1j
|-
|5
|3
|Bitcoin script hash
|
|-
|21
|4
|Bitcoin (compact) public key (proposed)
|
|-
|52
|M or N
|Namecoin pubkey hash
|NATX6zEUNfxfvgVwz8qVnnw3hLhhYXhgQn
|-
|111
|m or n
|Bitcoin testnet pubkey hash
|mkJ7Bf5chdfw61d1m7gnDVAQV3EQQAb8iz
|-
|128
|5
|Private key
|
|-
|196
|2
|Bitcoin testnet script hash
|
|-
|?
|L
|Litecoin pubkey hash
|LhK2kQwiaAvhjWY799cZvMyYwnQAcxkarr
|-
|?
|g
|GeistGeld pubkey hash
|gK5Lx6ypWgr69Gw9yGzE6dsA7kcuCRZRK
|-
|?
|?
|Tenebrix pubkey hash
|
|-
|?
|x
|ixcoin pubkey hash
|xoKDFH4uWpyzxUcCC5jCLFujRKayv3HHcV
|-
|?
|s
|Solidcoin pubkey hash
|sXNaMoYBocjcQJRLK53dkaQ5mWuKfvHB9f
|}

Base58Check encoding

2012-02-19T06:35:07Z

Holy-Fire: /* Features of Base58Check */ P2SH isn't in use yet

A modified Base 58 encoding known as '''Base58Check''' is used for encoding [[Bitcoin address]]es.

More generically, Base58Check encoding is used for encoding byte arrays in Bitcoin into human-typable strings. A Bitcoin address is simply a Base58Check-encoded string with a 20-byte payload, the payload being the hash of the [[public key]] associated with the address.

The original Bitcoin client source code discusses the reasoning behind base58 encoding:

base58.h:
// Why base-58 instead of standard base-64 encoding?
// - Don't want 0OIl characters that look the same in some fonts and
// could be used to create visually identical looking account numbers.
// - A string with non-alphanumeric characters is not as easily accepted as an account number.
// - E-mail usually won't line-break if there's no punctuation to break at.
// - Doubleclicking selects the whole number as one word if it's all alphanumeric.

==Features of Base58Check==
Base58Check has the following features:
* An arbitrarily sized payload.
* A set of 58 alphanumeric symbols consisting of easily distinguished uppercase and lowercase letters (0OIl are not used)
* One byte of version/application information. Bitcoin addresses use 0x00 for this byte (future ones may use 0x05).
* Four bytes (32 bits) of SHA256-based error checking code. This code can be used to automatically detect and possibly correct typographical errors.
* An extra step for preservation of leading zeroes in the data.

==Creating a Base58Check string==
A Base58Check string is created from a version/application byte and payload as follows.
# Take the version/application byte and payload bytes, and concatenate them together (bytewise).
# Take the first four bytes of SHA256(SHA256(results of step 1))
# Concatenate the results of step 1 and the results of step 2 together (bytewise).
# Treating the results of step 3 - a series of bytes - as a single big-endian bignumber, convert to base-58 using normal mathematical steps (bignumber division) and the base-58 alphabet described below. The result should be normalized to not have any leading base-58 zeroes (character '1').
# The leading character '1', which has a value of zero in base58, is reserved for representing an entire leading zero '''byte''', as when it is in a leading position, has no value as a base-58 symbol. There can be one or more leading '1's when necessary to represent one or more leading zero bytes. Count the number of leading zero bytes that were the result of step 3 (for old Bitcoin addresses, there will always be at least one for the version/application byte; for new addresses, there will never be any). Each leading zero byte shall be represented by its own character '1' in the final result.
# Concatenate the 1's from step 5 with the results of step 4. '''This is the Base58Check result.'''

==Encoding a Bitcoin address==
A Bitcoin address is based on any [[ECDSA]] [[secp256k1]] public/private [[key pair]].

A Bitcoin address is the Base58Check encoding of the hash of the associated [[script]]. Specifically, it is Base58Check(5,[[RIPEMD160]]([[SHA256]]([[script]]))), with the following constraints:
* [[RIPEMD160]] and [[SHA256]] in this case are always exactly 20 and 32 unsigned bytes respectively. These are big-endian (most significant byte first). (Beware of [[bignumber]] implementations that clip leading 0x00 bytes, or prepend extra 0x00 bytes to indicate sign - your code must handle these cases properly or else you may generate valid-looking addresses which can be sent to, but cannot be spent from - which would lead to the permanent loss of coins.)
* 0 refers to the version/application byte.

Because of the 0x05 version/application byte, Bitcoin addresses always start with the digit '3'.

==Encoding a private key==
Base58Check encoding is also used for encoding [[private key]]s in the [[Wallet Import Format]]. This is formed exactly the same as a Bitcoin address, except that 0x80 is used for the version/application byte, and the payload is 32 bytes instead of 20 (a private key in Bitcoin is a single 32-byte unsigned big-endian integer). Such encodings will always yield a 51-character string that starts with '5', or more specifically, either '5H', '5J', or '5K'.

==Base58 symbol chart==
The Base58 symbol chart used in Bitcoin is specific to the Bitcoin project and is not intended to be the same as any other Base58 implementation used outside the context of Bitcoin.
{| class="wikitable"
|-
!Value
!Character
!Value
!Character
!Value
|Character
!Value
!Character
|-
|0
|1
|1
|2
|2
|3
|3
|4
|-
|4
|5
|5
|6
|6
|7
|7
|8
|-
|8
|9
|9
|A
|10
|B
|11
|C
|-
|12
|D
|13
|E
|14
|F
|15
|G
|-
|16
|H
|17
|J
|18
|K
|19
|L
|-
|20
|M
|21
|N
|22
|P
|23
|Q
|-
|24
|R
|25
|S
|26
|T
|27
|U
|-
|28
|V
|29
|W
|30
|X
|31
|Y
|-
|32
|Z
|33
|a
|34
|b
|35
|c
|-
|36
|d
|37
|e
|38
|f
|39
|g
|-
|40
|h
|41
|i
|42
|j
|43
|k
|-
|44
|m
|45
|n
|46
|o
|47
|p
|-
|48
|q
|49
|r
|50
|s
|51
|t
|-
|52
|u
|53
|v
|54
|w
|55
|x
|-
|56
|y
|57
|z
|}

The algorithm for encoding address_byte_string (consisting of 0x01 + hash + 4-byte_check_code) is

code_string = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
x = convert_bytes_to_big_integer(hash_result)

output_string = ""

while(x > 0)
{
(x, remainder) = divide(x, 58)
output_string.append(code_string[remainder])
}

repeat(number_of_leading_zero_bytes_in_hash)
{
output_string.append(code_string[0]);
}

output_string.reverse();

==Version bytes==
Here are some common version bytes:

{| class="wikitable"
|-
!Decimal version
!Leading symbol
!Use
|-
|0
|1
|Bitcoin pubkey hash
|-
|5
|3
|Bitcoin script hash
|-
|21
|4
|Bitcoin (compact) public key (proposed)
|-
|52
|M or N
|Namecoin pubkey hash
|-
|128
|5
|Private key
|-
|111
|m or n
|Bitcoin testnet pubkey hash
|-
|196
|2
|Bitcoin testnet script hash
|}
[[List of address prefixes]] is a more complete list.

== Source ==
https://github.com/bitcoin/bitcoin/blob/master/src/base58.h

== Relevant functions in source code ==
* inline string EncodeBase58Check(const vector<unsigned char>& vchIn)
* inline bool DecodeBase58Check(const char* psz, vector<unsigned char>& vchRet)
* inline bool DecodeBase58Check(const string& str, vector<unsigned char>& vchRet)

[[Category:Technical]]

Invoice address

2012-02-19T06:33:17Z

Holy-Fire: + List of address prefixes

A '''Bitcoin address''', or simply '''address''', is an identifier of approximately 34 alphanumeric characters, beginning with the number 1 or 3, that represents a possible destination for a Bitcoin payment.
Addresses can be generated at no cost by any user of Bitcoin.
For example, using [[wxBitcoin]], one can click "Get Address" and be assigned an address.
It is also possible to get a Bitcoin address simply by creating an account at an exchange, to which a Bitcoin address will be automatically assigned.

An example of a Bitcoin address is ''37muSN5ZrukVTvyVh3mT5Zc5ew9L9CBare''.

==A Bitcoin address is like an e-mail address==
Like e-mail, you can send Bitcoins to a person by sending Bitcoins to their address. Somewhat unlike e-mail, one person can, and is encouraged, to have an unlimited number of different Bitcoin addresses. It is recommended that you use a unique address for each transaction. Most Bitcoin software and websites will help with this, by generating a brand new address each time you perform a transaction, or will provide a button you can click for a new one.

When using a web site that accepts Bitcoins or holds Bitcoin balances on your behalf, that website will assign a Bitcoin address to your account, so you can transfer funds into your account at the site. Very much unlike e-mail, this address will probably change every time funds come in, but the previous addresses will usually remain permanently valid for receiving additional funds. When you send Bitcoins to your account at a web site, they will usually be credited to your account at that web site within an hour (depending on the site's policy) to ensure that the transaction is [[confirmation|confirmed]].

==Addresses can be created offline==
Creating addresses can be done without any Internet connection or contact with the Bitcoin network. Creating addresses does not consume any resources on the network - the network only knows about an address when it is first used in a transaction. Because addresses can be created so easily and at no cost, it is trivial to create temporary "throwaway" addresses that can be discarded if never needed.

It is also possible to create large batches of addresses offline, using other software tools. Generating batches of addresses is useful in several scenarios, such as e-commerce websites where a unique pre-generated address is dispensed to each customer who chooses a "pay with Bitcoin" option.

==Addresses are case sensitive and exact==
Bitcoin addresses are case-sensitive. Bitcoin addresses should be copied and pasted using the computer's clipboard wherever possible.

If you hand-key a Bitcoin address, and each character is not transcribed exactly - including capitalization - the incorrect address will most likely be rejected by the Bitcoin client. You will have to check your entry and try again.

The probability that a mistyped address is accepted as being valid is 1 in 232 or approximately 1 in 4.29 billion.

==Most addresses have a "private key"==
For most addresses, there is a corresponding secret number known as a [[private key]].
When using a Bitcoin client, private key numbers are typically stored in the [[wallet file]]. The private key has a special purpose - it is mathematically needed to create transactions acceptable to the Bitcoin network that respend the funds originally sent to the address. If the private key to an address is lost (for example, in a hard drive crash and the user didn't have backups of the wallet file), any associated Bitcoins are lost forever.

==What's in an address==
Most Bitcoin addresses are 34 characters.
They consist of random digits and uppercase and lowercase letters, with the exception that the uppercase letter "O", uppercase letter "I", lowercase letter "l", and the number "0" are never used to prevent visual ambiguity.

Some Bitcoin addresses can be shorter than 34 characters - these are completely valid.
A significant percentage of Bitcoin addresses are only 33 characters, and some older addresses may be even shorter.
Every Bitcoin address stands for a number - somewhat like an account number. These shorter addresses are valid simply because they stand for numbers that happen to start with zeroes, and when the zeroes are omitted, the encoded address gets shorter.

Several of the characters inside a Bitcoin address are used as a checksum so that typographical errors can be automatically detected and rejected.

==See Also==
* [[Technical background of Bitcoin addresses]]
* [[List of address prefixes]]

[[Category:Vocabulary]]

Base58Check encoding

2012-02-19T06:32:49Z

Holy-Fire: /* Version bytes */ + List of address prefixes

A modified Base 58 encoding known as '''Base58Check''' is used for encoding [[Bitcoin address]]es.

More generically, Base58Check encoding is used for encoding byte arrays in Bitcoin into human-typable strings. A Bitcoin address is simply a Base58Check-encoded string with a 20-byte payload, the payload being the hash of the [[public key]] associated with the address.

The original Bitcoin client source code discusses the reasoning behind base58 encoding:

base58.h:
// Why base-58 instead of standard base-64 encoding?
// - Don't want 0OIl characters that look the same in some fonts and
// could be used to create visually identical looking account numbers.
// - A string with non-alphanumeric characters is not as easily accepted as an account number.
// - E-mail usually won't line-break if there's no punctuation to break at.
// - Doubleclicking selects the whole number as one word if it's all alphanumeric.

==Features of Base58Check==
Base58Check has the following features:
* An arbitrarily sized payload.
* A set of 58 alphanumeric symbols consisting of easily distinguished uppercase and lowercase letters (0OIl are not used)
* One byte of version/application information. Bitcoin addresses use 0x05 for this byte (older ones used 0x00).
* Four bytes (32 bits) of SHA256-based error checking code. This code can be used to automatically detect and possibly correct typographical errors.
* An extra step for preservation of leading zeroes in the data.

==Creating a Base58Check string==
A Base58Check string is created from a version/application byte and payload as follows.
# Take the version/application byte and payload bytes, and concatenate them together (bytewise).
# Take the first four bytes of SHA256(SHA256(results of step 1))
# Concatenate the results of step 1 and the results of step 2 together (bytewise).
# Treating the results of step 3 - a series of bytes - as a single big-endian bignumber, convert to base-58 using normal mathematical steps (bignumber division) and the base-58 alphabet described below. The result should be normalized to not have any leading base-58 zeroes (character '1').
# The leading character '1', which has a value of zero in base58, is reserved for representing an entire leading zero '''byte''', as when it is in a leading position, has no value as a base-58 symbol. There can be one or more leading '1's when necessary to represent one or more leading zero bytes. Count the number of leading zero bytes that were the result of step 3 (for old Bitcoin addresses, there will always be at least one for the version/application byte; for new addresses, there will never be any). Each leading zero byte shall be represented by its own character '1' in the final result.
# Concatenate the 1's from step 5 with the results of step 4. '''This is the Base58Check result.'''

==Encoding a Bitcoin address==
A Bitcoin address is based on any [[ECDSA]] [[secp256k1]] public/private [[key pair]].

A Bitcoin address is the Base58Check encoding of the hash of the associated [[script]]. Specifically, it is Base58Check(5,[[RIPEMD160]]([[SHA256]]([[script]]))), with the following constraints:
* [[RIPEMD160]] and [[SHA256]] in this case are always exactly 20 and 32 unsigned bytes respectively. These are big-endian (most significant byte first). (Beware of [[bignumber]] implementations that clip leading 0x00 bytes, or prepend extra 0x00 bytes to indicate sign - your code must handle these cases properly or else you may generate valid-looking addresses which can be sent to, but cannot be spent from - which would lead to the permanent loss of coins.)
* 0 refers to the version/application byte.

Because of the 0x05 version/application byte, Bitcoin addresses always start with the digit '3'.

==Encoding a private key==
Base58Check encoding is also used for encoding [[private key]]s in the [[Wallet Import Format]]. This is formed exactly the same as a Bitcoin address, except that 0x80 is used for the version/application byte, and the payload is 32 bytes instead of 20 (a private key in Bitcoin is a single 32-byte unsigned big-endian integer). Such encodings will always yield a 51-character string that starts with '5', or more specifically, either '5H', '5J', or '5K'.

==Base58 symbol chart==
The Base58 symbol chart used in Bitcoin is specific to the Bitcoin project and is not intended to be the same as any other Base58 implementation used outside the context of Bitcoin.
{| class="wikitable"
|-
!Value
!Character
!Value
!Character
!Value
|Character
!Value
!Character
|-
|0
|1
|1
|2
|2
|3
|3
|4
|-
|4
|5
|5
|6
|6
|7
|7
|8
|-
|8
|9
|9
|A
|10
|B
|11
|C
|-
|12
|D
|13
|E
|14
|F
|15
|G
|-
|16
|H
|17
|J
|18
|K
|19
|L
|-
|20
|M
|21
|N
|22
|P
|23
|Q
|-
|24
|R
|25
|S
|26
|T
|27
|U
|-
|28
|V
|29
|W
|30
|X
|31
|Y
|-
|32
|Z
|33
|a
|34
|b
|35
|c
|-
|36
|d
|37
|e
|38
|f
|39
|g
|-
|40
|h
|41
|i
|42
|j
|43
|k
|-
|44
|m
|45
|n
|46
|o
|47
|p
|-
|48
|q
|49
|r
|50
|s
|51
|t
|-
|52
|u
|53
|v
|54
|w
|55
|x
|-
|56
|y
|57
|z
|}

The algorithm for encoding address_byte_string (consisting of 0x01 + hash + 4-byte_check_code) is

code_string = "123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz"
x = convert_bytes_to_big_integer(hash_result)

output_string = ""

while(x > 0)
{
(x, remainder) = divide(x, 58)
output_string.append(code_string[remainder])
}

repeat(number_of_leading_zero_bytes_in_hash)
{
output_string.append(code_string[0]);
}

output_string.reverse();

==Version bytes==
Here are some common version bytes:

{| class="wikitable"
|-
!Decimal version
!Leading symbol
!Use
|-
|0
|1
|Bitcoin pubkey hash
|-
|5
|3
|Bitcoin script hash
|-
|21
|4
|Bitcoin (compact) public key (proposed)
|-
|52
|M or N
|Namecoin pubkey hash
|-
|128
|5
|Private key
|-
|111
|m or n
|Bitcoin testnet pubkey hash
|-
|196
|2
|Bitcoin testnet script hash
|}
[[List of address prefixes]] is a more complete list.

== Source ==
https://github.com/bitcoin/bitcoin/blob/master/src/base58.h

== Relevant functions in source code ==
* inline string EncodeBase58Check(const vector<unsigned char>& vchIn)
* inline bool DecodeBase58Check(const char* psz, vector<unsigned char>& vchRet)
* inline bool DecodeBase58Check(const string& str, vector<unsigned char>& vchRet)

[[Category:Technical]]

List of address prefixes

2012-02-19T06:31:39Z

Holy-Fire: Create List of address prefixes. Note: Incomplete, and there may be inaccuracies.

Blockchain-based currencies use addresses, which are a [[Base58Check encoding]] of some hash, typically that of a public key. The encoding includes a version byte, which affects the first character in the address. The following is a list of some prefixes which are in use.

{| class="wikitable"
|-
!Decimal version
!Leading symbol
!Use
!Example
|-
|0
|1
|Bitcoin pubkey hash
|12CPLrAUPvhVwjZqBgww3sLdEg4Z888R1j
|-
|5
|3
|Bitcoin script hash
|
|-
|21
|4
|Bitcoin (compact) public key (proposed)
|
|-
|52
|M or N
|Namecoin pubkey hash
|NATX6zEUNfxfvgVwz8qVnnw3hLhhYXhgQn
|-
|128
|5
|Private key
|
|-
|111
|m or n
|Bitcoin testnet pubkey hash
|mkJ7Bf5chdfw61d1m7gnDVAQV3EQQAb8iz
|-
|196
|2
|Bitcoin testnet script hash
|
|-
|?
|L
|Litecoin pubkey hash
|LhK2kQwiaAvhjWY799cZvMyYwnQAcxkarr
|-
|?
|g
|GeistGeld pubkey hash
|gK5Lx6ypWgr69Gw9yGzE6dsA7kcuCRZRK
|-
|?
|?
|Tenebrix pubkey hash
|
|-
|?
|x
|ixc0in pubkey hash
|xoKDFH4uWpyzxUcCC5jCLFujRKayv3HHcV
|-
|?
|s
|Solidcoin pubkey hash
|sXNaMoYBocjcQJRLK53dkaQ5mWuKfvHB9f
|}

Donation-accepting organizations and projects

2012-01-13T08:23:20Z

Holy-Fire: fix link

Here is a list of organizations that accept bitcoin donations.
Only notable donation-accepting sites should be added here.

{| class="wikitable"
|-
! Organization
! Purpose
! Donation Page
|-
|[http://www.anonyops.com/index.php Anonyops.com]
|Website dedicated to bringing people up to date with Anonymous actions, operations, and interesting news.
|http://anonyops.com/bitcoindonate.php
|-
|'''[http://www.archive.org/ Archive.org]'''
|Internet Archive is working towards the goal of Universal Access to All Knowledge. We digitize books, collect video, music and the World Wide Web, and take contributions of digital media from anyone who would like their materials preserved. We provide access to these vast collections to millions of people each day. All for free. Thank you for your support.
|http://www.archive.org/about/faqs.php#311
|-
|[http://www.indiegogo.com/commonsense A Liberty Upgrade for America (IndieGoGo)]
|Join us as we reach 1.6 million Americans with a message of liberty!
|http://www.indiegogo.com/commonsense
|-
|[http://anapnea.org Anapnea]
|An open ethical shell network aiming to create a community with a spirit of productivity, learning and freedom, to give you a breath of fresh air. Operates an open Gentoo Linux shell network that is accessed daily by hundreds of ethical hackers, developers, designers and geeks around the world.
|[https://twitter.com/anapnea/status/78118988848185345 Bitcoin Donation Address]
|-
|[http://www.anonnews.org/ Anonnews.org]
|Open news platform for Anonymous
|http://anonnews.org/bitcoin.html
|-
|[http://awesome.naquadah.org/ awesome]
|Window manager for X11
|http://awesome.naquadah.org/community/
|-
|[http://www.ezyorg.com/ Organizing & Planning Tool]
|Great tool to organize your next party or business meeting
|http://ezyorg.com/
|-|-
|[https://iplayernotifier.appspot.com/ BBC iPlayer Notifier]
|Email and Google Talk notification of new content available on BBC iPlayer
|https://iplayernotifier.appspot.com/
|-
|[http://www.beatingdebt.org/ BeatingDebt.org]
|Teaching debt prevention by placing educational ads, supporting debt prevention groups, and providing online resources.
|http://www.beatingdebt.org/donate.php#BitCoinDonation
|-
|[http://www.bitcharity.org/ BitCharity]
|Use Bitcoins to donate to your favorite charity
|http://www.bitcharity.org
|-
|[http://www.bluetile.org Bluetile]
|Tiling window manager for GNOME
|http://www.bluetile.org/#development
|-
|[http://brmlab.cz/ Brmlab, hackerspace]
|The first hackerspace in the Czech Republic
|http://brmlab.cz/project/bitcoin
|-
|[http://c4ss.org/ Center for a Stateless Society]
|Builds public awareness of, and support for, market anarchism
|http://c4ss.org/support-the-center
|-
|[http://www.cheat-sheets.org/ Cheat-Sheets.org]
|All cheat sheets, round-ups, quick reference cards, quick reference guides and quick reference sheets in one page.
|[http://www.cheat-sheets.org/ cheat-sheets.org]
|-
|[http://www.chambaproject.in/ Chamba Project]
|An effort to create a Swathanthra (Free/Libre/Open/Mukt) Animation Movie by pooling in contributions from people around the world and funding artists directly.
|[http://www.chambaproject.in/contribute/ http://www.chambaproject.in/contribute/]
|-
|[http://www.bitcoinsreview.com Consumer - Merchant Trust Project]
|An initiative to increase trust between Consumer and Bitcoin Merchants. All proceeds go to the websites fund, which pays for various things such as web-hosting and advertisement.
|http://www.bitcoinsreview.com/donate/
|-
|[http://convergence.io Convergence - Moving beyond Certificate Authorities]
|An agile, distributed, and secure strategy for replacing Certificate Authorities.
|http://convergence.io/involved.html
|-
|[http://ccbib.org Creative Commons Bibliothek]
|A Library dedicated to free books. Free meaning either "Creative Commons" or "out of copyright". The source code for all books is online to ease reprinting with any custom layout. Local groups produce paper versions for lending.
|http://ccbib.org/donate/
|-
|[http://www.cryto.net/ Cryto Coding Collective]
|A non-profit collective of independent developers and contributors that strive for real innovation. Unhindered by monetary incentive, arbitrary guidelines or authoritarian coordinators, it allows for an environment where real innovation takes place. Provides infrastructure like a storage grid, IRC network, and hosting.
|http://www.cryto.net/donate/
|-
|[http://www.DecryptedMatrix.com/ Decrypted Matrix ]
|GOALS: Elevate Human Awareness, Expose Greed & Corruption, Learn from [true] History, Distribute Beneficial Knowledge, Advance [suppressed] Technology, Protect Organic Agriculture, Maximize Human Potential, Promote Global Solutions, Re-integrate with Nature, Act with Love in all
|http://www.DecryptedMatrix.com
|-
|[http://www.degenernet.com/ Degenernet Radio]
|Online radio station founded in 2002 dedicated to promoting independent music from all genres. Music available from [http://www.degenernet.com www.degenernet.com]and on the [http://apps.facebook.com/degenernet Degenernet Radio Facebook App].
|http://www.degenernet.com/donate.php
|-
|[https://www.diasporafoundation.org/donate#bitcoin Diaspora Foundation]
|The people behind Diaspora, a distributed "social network". They're also running one public Diaspora server ([http://joindiaspora.com joindiaspora.com]).
|https://www.diasporafoundation.org/donate#bitcoin
|-
|[http://opensource.doppelstern.com Doppelstern Antispam]
|Doppelstern Antispam signatures for ClamAV
|http://opensource.doppelstern.com
|-
|[http://www.dosbox.com/ DOSBox]
|An x86 emulator with DOS
|http://www.dosbox.com/crew.php
|-
|[http://spices.org.my/ Early Intervention Program at SPICES]
|An established non-profit organization providing services to children with learning disabilities since 1997
|http://spices.org.my/be-involved/donations/
|-
|[http://encyclopediadramatica.ch/Main_Page Encyclopedia Dramatica]
|4chan's Wikipedia
|http://encyclopediadramatica.ch/donate.php
|-
|[https://www.erowid.org/ Erowid]
|Online library of information about psychoactive plants and chemicals and other topics on altered states of consciousness such as meditation and lucid dreaming.
|https://www.erowid.org/donations/donations_bitcoin.php
|-
|[http://eudemocracia.org/english.html Eudemocracia] NGO
|Dedicated to the creation of a modern form of government that combines these two concepts: direct democracy and internet.
|http://wiki.eudemocracia.org/en/donaciones
|-
|[http://www.foo.be/forban/ Forban]
|Filesharing protocol for local area networks
|http://www.foo.be/forban/
|-
|[http://420chan.org/ 420chan]
|Imageboard community
|http://420chan.org/donate/
|-
|[http://freedomboxfoundation.org FreedomBox Foundation]
|Non-profit turning small plug computers into personal servers that guard your privacy, anonymity and security.
|https://freedomboxfoundation.org/donate
|-
|[http://www.fsf.org Free Software Foundation]
|Worldwide advocate for software freedom and host organization for the GNU Project.
|https://my.fsf.org/donate/other
|-
|[http://www.freetalklive.com/ Free Talk Live]
|Help spread the message of liberty by donating to a liberty leaning nationally syndicated radio show!
|http://www.freetalklive.com/bitcoin
|-
|[http://freedomainradio.com/ Freedomain Radio]
|Online philosophical conversation about freedom, religion, the state, and the family
|http://board.freedomainradio.com/forums/t/30241.aspx
|-
|[http://www.freehal.org/ FreeHAL]
|a self-learning artificial intelligence available as free software
|http://www.freehal.net/funds/?p=do&l=en
|-
|[http://www.gentlelan.de/ GentleLAN]
|Since many years free private LANs in Bremen / Germany
|http://www.gentlelan.de/?page_id=193
|-
|[http://www.reddit.com/r/hackbloc HackBloc on Reddit]
|Hacktivism, Crypto-anarchy, Darknets.
|http://www.reddit.com/r/hackbloc
|-
|[http://www.heavensentgaming.com Heaven Sent Gaming]
|Heaven Sent Gaming is a new media entertainment group founded by Mario Lucero and Isabel Ruiz, in 2006, as a game development team.
|http://heavensentgaming.com/support-and-donations/
|-
|[http://www.helplinux.ru Help Linux]
|Help Linux is the Russian volunteer project aimed to help people with linux. This projects helps anyone to find a skilled in some questions person and ask for help directly.
|http://helplinux.ourproject.org/wiki/about:start
|-
|[http://i2p2.de/ I2P Anonymous Network]
|Anonymising network similar to tor
|http://www.i2p2.de/donate.html
|-
|[http://www.intercom.gs/ Intercom - Emergency Communications Division]
|We Build Censorship Resistant Phone and Communications Networks
|http://www.intercom.gs/support.html
|-
|[http://www.partito-pirata.it/ Italian Pirate Party]
|Italian Pirate Party - Associazione Partito Pirata Italia
|http://www.partito-pirata.it/magazzino/payBTC.html
|-
|[http://lifeboat.com Lifeboat Foundation]
|The Lifeboat Foundation is a nonprofit nongovernmental organization dedicated to encouraging scientific advancements while helping humanity survive existential risks and possible misuse of increasingly powerful technologies, including genetic engineering, nanotechnology, and robotics/AI, as we move towards the Singularity. (Currently offering to double all Bitcoin donations.)
|https://lifeboat.com/ex/summer.growth
|-
|[http://lorea.org/ Lorea]
|A distributed and federated nodal organization of entities working on integrating and pushing available free and open source technologies and networks, for social networking, social economy and autonomy of the people.
|https://n-1.cc/pg/pages/view/14888/
|-
|[http://biohackers.la/ Los Angeles Biohackers]
|Grass-roots biotechnology lab in downtown Los Angeles
|http://www.socal-diybio.org/Main_Page#Donate
|-
|[http://la.indymedia.org/ Los Angeles Indymedia]
|User-generated left-wing news.
|http://la.indymedia.org/
|-
|[http://love2d.org/ LÖVE]
|An open source 2D game engine.
|http://love2d.org/
|-
|[http://mars.radiome.me M.A.R.S. Radio Modern Alternative Rock Splendor ]
|M.A.R.S Radio is an online radio station playing 24/7/365 commercial free alternative rock at 192 Kbps. M.A.R.S. Radio is pleased to provide listeners FM+ audio quality. M.A.R.S. Radio is the first online music radio station to accept Bitcoin donations.
|http://radiome.me/
|-
|[https://github.com/FellowTraveler/Open-Transactions/ Open Transactions]
|Easy-to-use, Financial Crypto and Digital Cash Library.
|https://github.com/FellowTraveler/Moneychanger
|-
|[http://opengameart.org/ OpenGameArt.org]
|Produces and hosts freely licensed art for use in open source games
|http://opengameart.org/content/donate-bitcoins
|-
|[http://www.openwall.com Openwall Project]
|Development of information security related free software, information security research, publications, and community activities aimed at making existing free software safer to use.
|http://www.openwall.com/donations/
|-
|[https://www.operationanonymous.org/ Operation Anonymous]
|Anonymous Political Group
|http://www.operationanonymous.org/
|-
|[http://www.organicdesign.co.nz OrganicDesign]
|A group developing methods and tools to support open-source bottom-up peer-to-peer governance for the people!
|http://www.organicdesign.co.nz
|-
|[http://www.paniq.cc paniq.cc]
|Music from the other side of the universe
|http://www.paniq.cc
|-
|[http://www.liberallibertario.org Partido Liberal Libertario]
|Libertarian Party of Argentina
|http://www.liberallibertario.org/aportes
|-
|[http://pioneerone.tv/ Pioneer One]
|TV series funded purely through donations
|https://twitter.com/pioneeronetv/status/36119594439544832
|-
|[http://plankhead.com/ Plankhead]
|Free/open source media and arts organization
|http://plankhead.com/donate
|-
|[http://plaztika.com/?lang=en Plaztika]
|Non-profit website (only runs on donations) that supports emerging visual artists. If you're an artist, this could be your website!
|http://plaztika.com/Who-are-we
|-
|[https://privacybox.de/index.en.html PrivacyBox]
|System for anonymous and non-trackable contact forms
|https://privacybox.de/donations.en.html
|-
|[http://bitcoinintro.com/project-hidden-treasure/ Project Hidden Treasure]
|BitcoinIntro.com operates "Project Hidden Treasure". As well as inform new Bitcoin users how to use and be secure with Bitcoin, we promote Bitcoin to new users by creating mini-keys, send Bitcoins to them, and distribute the private keys and a recovery instruction URL in Geocaches.
| http://bitcoinintro.com/project-hidden-treasure/
|-
|[http://prometheusfusionperfection.com/ Prometheus Fusion Perfection]
|Open source nuclear fusion research
|http://prometheusfusionperfection.com/2011/02/04/bitcoin-fundraiser/
|-
|[http://protestbarrick.net/ Protest Barrick]
|A global campaign against the world's largest gold miner
|[https://www.mybitcoin.com/sci/paypage.php?amount=20.00&currency=USD&payee_bcaddr=125Gwb3Mn9KSaCS8QN9LQy5k6RPUHEFruV&payee_name=Protest+Barrick+Fund&note=Donate+NOW+to+end+corporate+impunity+in+gold+mining%21 Donate with Bitcoin]
|-
|[http://queeky.com/ Queeky]
|an online drawing community with special drawing tools and creative users from all around the world
|http://www.queeky.com/content/support-queeky-and-donate
|-
|[http://www.recycles.org/ Recycles.Org]
|Nonprofit Recycling and ReUse Network - Nationwide (USA) technology exchange clearinghouse for nonprofit organizations
|http://www.recycles.org/computer/donation/support/
|-
|[https://ripplepay.com/ Ripple]
|Payment system based on trust networks
|https://ripplepay.com/donate/
|-
| [https://riseup.net/ Riseup]
| Tech collective who aim to [https://help.riseup.net/en/about-us aid in the creation of a free society, (...) engaged in struggles against capitalism and other forms of oppression]
| https://help.riseup.net/en/donate#bitcoin
|-
|[http://rusinfo.cc/ RusInfo]
|Russian info agency
|http://rusinfo.cc/help
|-
|[http://seasteading.org The Seasteading Institute]
|To further the establishment and growth of permanent, autonomous ocean communities, enabling innovation with new political and social systems.
|http://twitter.com/#!/patrissimo/status/76392851558244353
|-
|[http://singinst.org Singularity Institute]
|Artificial Intelligence
|http://singinst.org/donate
|-
|[http://somefunnypranks.com/ SomeFunnyPranks.com]
|Loosen your buckle and have a chuckle.
|http://somefunnypranks.com/
|-
| [http://www.sparkleshare.org/ SparkleShare]
| A Free and Open Source host it yourself replacement for file syncing services like Dropbox. It uses the distributed version control system Git as a backend.
| [http://www.sparkleshare.org/support-us/ Bitcoin Donation Address]
|-
|[http://www.demokracjabezposrednia.pl Stowarzyszenie Więcej Demokracji]
|Stowarzyszenie Więcej Demokracji is an association for direct democracy in Poland. We believe that direct democracy is a hope for every country (not only for corrupt Poland). Please help us and donate.
|http://www.demokracjabezposrednia.pl/donate
|-
|[http://wiki.sugarlabs.org Sugar Labs]
|[http://wiki.sugarlabs.org/go/What_is_Sugar%3F Sugar] is a learning environment that reinvents how computers are used for education.
|http://wiki.sugarlabs.org/go/Donate
|-
|[http://gorod-solnca.org/ Sun City]
|Ukrainian centre for children in difficult circumstances
|http://sms.gorod-solnca.org/
|-
|[http://www.symphonyofscience.com/ Symphony of Science]
|A musical project headed by John Boswell, to deliver scientific knowledge in musical form.
|http://www.symphonyofscience.com/
|-
|[http://tahoe-lafs.org/ Tahoe-LAFS]
|A distributed filesystem with funky redundancy properties
|http://tahoe-lafs.org/trac/tahoe-lafs/wiki/BitCoinPage
|-
|[http://tangorin.com Tangorin Japanese Dictionary]
|Tangorin is a free online Japanese dictionary in development since October 2007 by a former Japanology student. It makes use of files provided mainly by The Electronic Dictionary Research and Development Group established within the Faculty of Information Technology at Monash University, Australia.
|http://tangorin.com/bitcoin
|-
|[http://the-alternative.co.uk/support-us/ The-alternative.co.uk]
|Alternative news and articles
|[http://the-alternative.co.uk/support-us/ Donation page]
|-
|[http://theexperiments.com The Experiments]
|A rock / punk band who's music is free to download and licensed under the Creative Commons
|[http://theexperiments.com Bitcoin Donation Address]
|-
|[http://theicarusproject.net The Icarus Project]
|A mutual aid/peer support organization dedicated to radical mental health
|[http://theicarusproject.net/about-us/donate-to-the-icarus-project Bitcoin Donation Address]
|-
|[https://freenetproject.org/ The Freenet Project]
|The Free Network
|https://freenetproject.org/donate.html
|-
| [http://ThePythonGameBook.com ThePythonGameBook]
| An free creative-commons / GPL - licensed wikibook to learn open source game programming using the programming language Python.
| [http://thepythongamebook.com/en:help?&#donating_money Bitcoin Donation Address]
|-
|[http://Tn3t.com/ TN3T LLC TOR Project]
|TN3T LLC operates 2 TOR exit nodes.
| [http://tn3t.com/donate.txt Bitcoin Donation Address]
|-
|[http://torchat.googlecode.com/ TorChat]
|A serverless encrypted anonymous instant messenger running on top of the Tor network
|http://torchat.googlecode.com/
|-
|[https://www.torservers.net/ Torservers.net]
|Runs [http://www.torproject.org/ Tor] relays and bridges
|https://www.torservers.net/donate.html#anonymous
|-
|[https://vaizard.org/ Vaizard institute]
| Backing people who want to make the world a better place by making their ideas real.
|https://vaizard.org/en/about/contacts/
|-
|-
|[http://wikileaks.org wikileaks]
| Whistleblower website
|http://wikileaks.org/support.html
|-
|[http://wlcentral.org/ WL Central]
|News, analysis and action related to wikileaks the famous website . Media and human rights organization covering Wikileaks news, corruption and human rights.
|http://wlcentral.org/q-a
|-
|[http://tmac.technitium.com/ Technitium]
|Technitium MAC Address Changer is a freeware software. We accept bitcoins as a contribution for the software.
|http://blog.technitium.com/2011/08/accepting-donations-again.html
|-
|[http://www.nycga.net/about/ Occupy Wall Street]
|Occupy Wall Street Support via the New York City General Assembly.
|http://www.nycga.net/how-to-help/
|-
|[http://www.expanton.com]
| Occupy Wall Street Support
|http://www.expanton.com/
|-
|[http://www.wakingupmovie.com Waking Up Movie Project]
|Waking Up is an open source film about a positive future for humanity, for a change. The film is in the making by several people, and you can contribute to it!
|http://www.wakingupmovie.com/2011/12/bitcoin-donations/
|-
|[https://wikispooks.com/wiki/Main_Page Wikispooks]
|An encyclopedia of deep political structures and events
|https://wikispooks.com/wiki/WikiSpooks:Donate
|}

==See Also==
* [http://witcoin.com/charities Charitable organizations] list on [[witcoin]]
* [http://ecdsa.org/fundraiser Fundraiser widgets]

Donation-accepting organizations and projects

2012-01-13T08:21:59Z

Holy-Fire: Don't post Bitcoin addresses here

Here is a list of organizations that accept bitcoin donations.
Only notable donation-accepting sites should be added here.

{| class="wikitable"
|-
! Organization
! Purpose
! Donation Page
|-
|[http://www.anonyops.com/index.php Anonyops.com]
|Website dedicated to bringing people up to date with Anonymous actions, operations, and interesting news.
|http://anonyops.com/bitcoindonate.php
|-
|'''[http://www.archive.org/ Archive.org]'''
|Internet Archive is working towards the goal of Universal Access to All Knowledge. We digitize books, collect video, music and the World Wide Web, and take contributions of digital media from anyone who would like their materials preserved. We provide access to these vast collections to millions of people each day. All for free. Thank you for your support.
|[http://www.archive.org/about/faqs.php#311]
|-
|[http://www.indiegogo.com/commonsense A Liberty Upgrade for America (IndieGoGo)]
|Join us as we reach 1.6 million Americans with a message of liberty!
|http://www.indiegogo.com/commonsense
|-
|[http://anapnea.org Anapnea]
|An open ethical shell network aiming to create a community with a spirit of productivity, learning and freedom, to give you a breath of fresh air. Operates an open Gentoo Linux shell network that is accessed daily by hundreds of ethical hackers, developers, designers and geeks around the world.
|[https://twitter.com/anapnea/status/78118988848185345 Bitcoin Donation Address]
|-
|[http://www.anonnews.org/ Anonnews.org]
|Open news platform for Anonymous
|http://anonnews.org/bitcoin.html
|-
|[http://awesome.naquadah.org/ awesome]
|Window manager for X11
|http://awesome.naquadah.org/community/
|-
|[http://www.ezyorg.com/ Organizing & Planning Tool]
|Great tool to organize your next party or business meeting
|http://ezyorg.com/
|-|-
|[https://iplayernotifier.appspot.com/ BBC iPlayer Notifier]
|Email and Google Talk notification of new content available on BBC iPlayer
|https://iplayernotifier.appspot.com/
|-
|[http://www.beatingdebt.org/ BeatingDebt.org]
|Teaching debt prevention by placing educational ads, supporting debt prevention groups, and providing online resources.
|http://www.beatingdebt.org/donate.php#BitCoinDonation
|-
|[http://www.bitcharity.org/ BitCharity]
|Use Bitcoins to donate to your favorite charity
|http://www.bitcharity.org
|-
|[http://www.bluetile.org Bluetile]
|Tiling window manager for GNOME
|http://www.bluetile.org/#development
|-
|[http://brmlab.cz/ Brmlab, hackerspace]
|The first hackerspace in the Czech Republic
|http://brmlab.cz/project/bitcoin
|-
|[http://c4ss.org/ Center for a Stateless Society]
|Builds public awareness of, and support for, market anarchism
|http://c4ss.org/support-the-center
|-
|[http://www.cheat-sheets.org/ Cheat-Sheets.org]
|All cheat sheets, round-ups, quick reference cards, quick reference guides and quick reference sheets in one page.
|[http://www.cheat-sheets.org/ cheat-sheets.org]
|-
|[http://www.chambaproject.in/ Chamba Project]
|An effort to create a Swathanthra (Free/Libre/Open/Mukt) Animation Movie by pooling in contributions from people around the world and funding artists directly.
|[http://www.chambaproject.in/contribute/ http://www.chambaproject.in/contribute/]
|-
|[http://www.bitcoinsreview.com Consumer - Merchant Trust Project]
|An initiative to increase trust between Consumer and Bitcoin Merchants. All proceeds go to the websites fund, which pays for various things such as web-hosting and advertisement.
|http://www.bitcoinsreview.com/donate/
|-
|[http://convergence.io Convergence - Moving beyond Certificate Authorities]
|An agile, distributed, and secure strategy for replacing Certificate Authorities.
|http://convergence.io/involved.html
|-
|[http://ccbib.org Creative Commons Bibliothek]
|A Library dedicated to free books. Free meaning either "Creative Commons" or "out of copyright". The source code for all books is online to ease reprinting with any custom layout. Local groups produce paper versions for lending.
|http://ccbib.org/donate/
|-
|[http://www.cryto.net/ Cryto Coding Collective]
|A non-profit collective of independent developers and contributors that strive for real innovation. Unhindered by monetary incentive, arbitrary guidelines or authoritarian coordinators, it allows for an environment where real innovation takes place. Provides infrastructure like a storage grid, IRC network, and hosting.
|http://www.cryto.net/donate/
|-
|[http://www.DecryptedMatrix.com/ Decrypted Matrix ]
|GOALS: Elevate Human Awareness, Expose Greed & Corruption, Learn from [true] History, Distribute Beneficial Knowledge, Advance [suppressed] Technology, Protect Organic Agriculture, Maximize Human Potential, Promote Global Solutions, Re-integrate with Nature, Act with Love in all
|http://www.DecryptedMatrix.com
|-
|[http://www.degenernet.com/ Degenernet Radio]
|Online radio station founded in 2002 dedicated to promoting independent music from all genres. Music available from [http://www.degenernet.com www.degenernet.com]and on the [http://apps.facebook.com/degenernet Degenernet Radio Facebook App].
|http://www.degenernet.com/donate.php
|-
|[https://www.diasporafoundation.org/donate#bitcoin Diaspora Foundation]
|The people behind Diaspora, a distributed "social network". They're also running one public Diaspora server ([http://joindiaspora.com joindiaspora.com]).
|https://www.diasporafoundation.org/donate#bitcoin
|-
|[http://opensource.doppelstern.com Doppelstern Antispam]
|Doppelstern Antispam signatures for ClamAV
|http://opensource.doppelstern.com
|-
|[http://www.dosbox.com/ DOSBox]
|An x86 emulator with DOS
|http://www.dosbox.com/crew.php
|-
|[http://spices.org.my/ Early Intervention Program at SPICES]
|An established non-profit organization providing services to children with learning disabilities since 1997
|http://spices.org.my/be-involved/donations/
|-
|[http://encyclopediadramatica.ch/Main_Page Encyclopedia Dramatica]
|4chan's Wikipedia
|http://encyclopediadramatica.ch/donate.php
|-
|[https://www.erowid.org/ Erowid]
|Online library of information about psychoactive plants and chemicals and other topics on altered states of consciousness such as meditation and lucid dreaming.
|https://www.erowid.org/donations/donations_bitcoin.php
|-
|[http://eudemocracia.org/english.html Eudemocracia] NGO
|Dedicated to the creation of a modern form of government that combines these two concepts: direct democracy and internet.
|http://wiki.eudemocracia.org/en/donaciones
|-
|[http://www.foo.be/forban/ Forban]
|Filesharing protocol for local area networks
|http://www.foo.be/forban/
|-
|[http://420chan.org/ 420chan]
|Imageboard community
|http://420chan.org/donate/
|-
|[http://freedomboxfoundation.org FreedomBox Foundation]
|Non-profit turning small plug computers into personal servers that guard your privacy, anonymity and security.
|https://freedomboxfoundation.org/donate
|-
|[http://www.fsf.org Free Software Foundation]
|Worldwide advocate for software freedom and host organization for the GNU Project.
|https://my.fsf.org/donate/other
|-
|[http://www.freetalklive.com/ Free Talk Live]
|Help spread the message of liberty by donating to a liberty leaning nationally syndicated radio show!
|http://www.freetalklive.com/bitcoin
|-
|[http://freedomainradio.com/ Freedomain Radio]
|Online philosophical conversation about freedom, religion, the state, and the family
|http://board.freedomainradio.com/forums/t/30241.aspx
|-
|[http://www.freehal.org/ FreeHAL]
|a self-learning artificial intelligence available as free software
|http://www.freehal.net/funds/?p=do&l=en
|-
|[http://www.gentlelan.de/ GentleLAN]
|Since many years free private LANs in Bremen / Germany
|http://www.gentlelan.de/?page_id=193
|-
|[http://www.reddit.com/r/hackbloc HackBloc on Reddit]
|Hacktivism, Crypto-anarchy, Darknets.
|http://www.reddit.com/r/hackbloc
|-
|[http://www.heavensentgaming.com Heaven Sent Gaming]
|Heaven Sent Gaming is a new media entertainment group founded by Mario Lucero and Isabel Ruiz, in 2006, as a game development team.
|http://heavensentgaming.com/support-and-donations/
|-
|[http://www.helplinux.ru Help Linux]
|Help Linux is the Russian volunteer project aimed to help people with linux. This projects helps anyone to find a skilled in some questions person and ask for help directly.
|http://helplinux.ourproject.org/wiki/about:start
|-
|[http://i2p2.de/ I2P Anonymous Network]
|Anonymising network similar to tor
|http://www.i2p2.de/donate.html
|-
|[http://www.intercom.gs/ Intercom - Emergency Communications Division]
|We Build Censorship Resistant Phone and Communications Networks
|http://www.intercom.gs/support.html
|-
|[http://www.partito-pirata.it/ Italian Pirate Party]
|Italian Pirate Party - Associazione Partito Pirata Italia
|http://www.partito-pirata.it/magazzino/payBTC.html
|-
|[http://lifeboat.com Lifeboat Foundation]
|The Lifeboat Foundation is a nonprofit nongovernmental organization dedicated to encouraging scientific advancements while helping humanity survive existential risks and possible misuse of increasingly powerful technologies, including genetic engineering, nanotechnology, and robotics/AI, as we move towards the Singularity. (Currently offering to double all Bitcoin donations.)
|https://lifeboat.com/ex/summer.growth
|-
|[http://lorea.org/ Lorea]
|A distributed and federated nodal organization of entities working on integrating and pushing available free and open source technologies and networks, for social networking, social economy and autonomy of the people.
|https://n-1.cc/pg/pages/view/14888/
|-
|[http://biohackers.la/ Los Angeles Biohackers]
|Grass-roots biotechnology lab in downtown Los Angeles
|http://www.socal-diybio.org/Main_Page#Donate
|-
|[http://la.indymedia.org/ Los Angeles Indymedia]
|User-generated left-wing news.
|http://la.indymedia.org/
|-
|[http://love2d.org/ LÖVE]
|An open source 2D game engine.
|http://love2d.org/
|-
|[http://mars.radiome.me M.A.R.S. Radio Modern Alternative Rock Splendor ]
|M.A.R.S Radio is an online radio station playing 24/7/365 commercial free alternative rock at 192 Kbps. M.A.R.S. Radio is pleased to provide listeners FM+ audio quality. M.A.R.S. Radio is the first online music radio station to accept Bitcoin donations.
|http://radiome.me/
|-
|[https://github.com/FellowTraveler/Open-Transactions/ Open Transactions]
|Easy-to-use, Financial Crypto and Digital Cash Library.
|https://github.com/FellowTraveler/Moneychanger
|-
|[http://opengameart.org/ OpenGameArt.org]
|Produces and hosts freely licensed art for use in open source games
|http://opengameart.org/content/donate-bitcoins
|-
|[http://www.openwall.com Openwall Project]
|Development of information security related free software, information security research, publications, and community activities aimed at making existing free software safer to use.
|http://www.openwall.com/donations/
|-
|[https://www.operationanonymous.org/ Operation Anonymous]
|Anonymous Political Group
|http://www.operationanonymous.org/
|-
|[http://www.organicdesign.co.nz OrganicDesign]
|A group developing methods and tools to support open-source bottom-up peer-to-peer governance for the people!
|http://www.organicdesign.co.nz
|-
|[http://www.paniq.cc paniq.cc]
|Music from the other side of the universe
|http://www.paniq.cc
|-
|[http://www.liberallibertario.org Partido Liberal Libertario]
|Libertarian Party of Argentina
|http://www.liberallibertario.org/aportes
|-
|[http://pioneerone.tv/ Pioneer One]
|TV series funded purely through donations
|https://twitter.com/pioneeronetv/status/36119594439544832
|-
|[http://plankhead.com/ Plankhead]
|Free/open source media and arts organization
|http://plankhead.com/donate
|-
|[http://plaztika.com/?lang=en Plaztika]
|Non-profit website (only runs on donations) that supports emerging visual artists. If you're an artist, this could be your website!
|http://plaztika.com/Who-are-we
|-
|[https://privacybox.de/index.en.html PrivacyBox]
|System for anonymous and non-trackable contact forms
|https://privacybox.de/donations.en.html
|-
|[http://bitcoinintro.com/project-hidden-treasure/ Project Hidden Treasure]
|BitcoinIntro.com operates "Project Hidden Treasure". As well as inform new Bitcoin users how to use and be secure with Bitcoin, we promote Bitcoin to new users by creating mini-keys, send Bitcoins to them, and distribute the private keys and a recovery instruction URL in Geocaches.
| http://bitcoinintro.com/project-hidden-treasure/
|-
|[http://prometheusfusionperfection.com/ Prometheus Fusion Perfection]
|Open source nuclear fusion research
|http://prometheusfusionperfection.com/2011/02/04/bitcoin-fundraiser/
|-
|[http://protestbarrick.net/ Protest Barrick]
|A global campaign against the world's largest gold miner
|[https://www.mybitcoin.com/sci/paypage.php?amount=20.00&currency=USD&payee_bcaddr=125Gwb3Mn9KSaCS8QN9LQy5k6RPUHEFruV&payee_name=Protest+Barrick+Fund&note=Donate+NOW+to+end+corporate+impunity+in+gold+mining%21 Donate with Bitcoin]
|-
|[http://queeky.com/ Queeky]
|an online drawing community with special drawing tools and creative users from all around the world
|http://www.queeky.com/content/support-queeky-and-donate
|-
|[http://www.recycles.org/ Recycles.Org]
|Nonprofit Recycling and ReUse Network - Nationwide (USA) technology exchange clearinghouse for nonprofit organizations
|http://www.recycles.org/computer/donation/support/
|-
|[https://ripplepay.com/ Ripple]
|Payment system based on trust networks
|https://ripplepay.com/donate/
|-
| [https://riseup.net/ Riseup]
| Tech collective who aim to [https://help.riseup.net/en/about-us aid in the creation of a free society, (...) engaged in struggles against capitalism and other forms of oppression]
| https://help.riseup.net/en/donate#bitcoin
|-
|[http://rusinfo.cc/ RusInfo]
|Russian info agency
|http://rusinfo.cc/help
|-
|[http://seasteading.org The Seasteading Institute]
|To further the establishment and growth of permanent, autonomous ocean communities, enabling innovation with new political and social systems.
|http://twitter.com/#!/patrissimo/status/76392851558244353
|-
|[http://singinst.org Singularity Institute]
|Artificial Intelligence
|http://singinst.org/donate
|-
|[http://somefunnypranks.com/ SomeFunnyPranks.com]
|Loosen your buckle and have a chuckle.
|http://somefunnypranks.com/
|-
| [http://www.sparkleshare.org/ SparkleShare]
| A Free and Open Source host it yourself replacement for file syncing services like Dropbox. It uses the distributed version control system Git as a backend.
| [http://www.sparkleshare.org/support-us/ Bitcoin Donation Address]
|-
|[http://www.demokracjabezposrednia.pl Stowarzyszenie Więcej Demokracji]
|Stowarzyszenie Więcej Demokracji is an association for direct democracy in Poland. We believe that direct democracy is a hope for every country (not only for corrupt Poland). Please help us and donate.
|http://www.demokracjabezposrednia.pl/donate
|-
|[http://wiki.sugarlabs.org Sugar Labs]
|[http://wiki.sugarlabs.org/go/What_is_Sugar%3F Sugar] is a learning environment that reinvents how computers are used for education.
|http://wiki.sugarlabs.org/go/Donate
|-
|[http://gorod-solnca.org/ Sun City]
|Ukrainian centre for children in difficult circumstances
|http://sms.gorod-solnca.org/
|-
|[http://www.symphonyofscience.com/ Symphony of Science]
|A musical project headed by John Boswell, to deliver scientific knowledge in musical form.
|http://www.symphonyofscience.com/
|-
|[http://tahoe-lafs.org/ Tahoe-LAFS]
|A distributed filesystem with funky redundancy properties
|http://tahoe-lafs.org/trac/tahoe-lafs/wiki/BitCoinPage
|-
|[http://tangorin.com Tangorin Japanese Dictionary]
|Tangorin is a free online Japanese dictionary in development since October 2007 by a former Japanology student. It makes use of files provided mainly by The Electronic Dictionary Research and Development Group established within the Faculty of Information Technology at Monash University, Australia.
|http://tangorin.com/bitcoin
|-
|[http://the-alternative.co.uk/support-us/ The-alternative.co.uk]
|Alternative news and articles
|[http://the-alternative.co.uk/support-us/ Donation page]
|-
|[http://theexperiments.com The Experiments]
|A rock / punk band who's music is free to download and licensed under the Creative Commons
|[http://theexperiments.com Bitcoin Donation Address]
|-
|[http://theicarusproject.net The Icarus Project]
|A mutual aid/peer support organization dedicated to radical mental health
|[http://theicarusproject.net/about-us/donate-to-the-icarus-project Bitcoin Donation Address]
|-
|[https://freenetproject.org/ The Freenet Project]
|The Free Network
|https://freenetproject.org/donate.html
|-
| [http://ThePythonGameBook.com ThePythonGameBook]
| An free creative-commons / GPL - licensed wikibook to learn open source game programming using the programming language Python.
| [http://thepythongamebook.com/en:help?&#donating_money Bitcoin Donation Address]
|-
|[http://Tn3t.com/ TN3T LLC TOR Project]
|TN3T LLC operates 2 TOR exit nodes.
| [http://tn3t.com/donate.txt Bitcoin Donation Address]
|-
|[http://torchat.googlecode.com/ TorChat]
|A serverless encrypted anonymous instant messenger running on top of the Tor network
|http://torchat.googlecode.com/
|-
|[https://www.torservers.net/ Torservers.net]
|Runs [http://www.torproject.org/ Tor] relays and bridges
|https://www.torservers.net/donate.html#anonymous
|-
|[https://vaizard.org/ Vaizard institute]
| Backing people who want to make the world a better place by making their ideas real.
|https://vaizard.org/en/about/contacts/
|-
|-
|[http://wikileaks.org wikileaks]
| Whistleblower website
|http://wikileaks.org/support.html
|-
|[http://wlcentral.org/ WL Central]
|News, analysis and action related to wikileaks the famous website . Media and human rights organization covering Wikileaks news, corruption and human rights.
|http://wlcentral.org/q-a
|-
|[http://tmac.technitium.com/ Technitium]
|Technitium MAC Address Changer is a freeware software. We accept bitcoins as a contribution for the software.
|http://blog.technitium.com/2011/08/accepting-donations-again.html
|-
|[http://www.nycga.net/about/ Occupy Wall Street]
|Occupy Wall Street Support via the New York City General Assembly.
|http://www.nycga.net/how-to-help/
|-
|[http://www.expanton.com]
| Occupy Wall Street Support
|http://www.expanton.com/
|-
|[http://www.wakingupmovie.com Waking Up Movie Project]
|Waking Up is an open source film about a positive future for humanity, for a change. The film is in the making by several people, and you can contribute to it!
|http://www.wakingupmovie.com/2011/12/bitcoin-donations/
|-
|[https://wikispooks.com/wiki/Main_Page Wikispooks]
|An encyclopedia of deep political structures and events
|https://wikispooks.com/wiki/WikiSpooks:Donate
|}

==See Also==
* [http://witcoin.com/charities Charitable organizations] list on [[witcoin]]
* [http://ecdsa.org/fundraiser Fundraiser widgets]

Meetups

2011-12-07T12:43:52Z

Holy-Fire: + Israel

Don't add everyone who's going in the "Who?" column, just prominent Bitcoin members and organizers. Also see [http://bitcoin.meetup.com bitcoin.meetup.com]

{| class="wikitable"
|-
! Group
! When?
! Where?
! Who?
! Other Notes
|-
| [http://metalab.at/wiki/Bitcoins Vienna, Austria]
| monthly - check the [http://metalab.at/wiki/Bitcoins wiki] or subscribe to the [http://lists.keisanki.net/listinfo/bitcoin mailinglist]
| [http://metalab.at/wiki/Lage Metalab], Vienna hacker space, Rathausstraße 6, 1010 Wien
| Bitcoin Group Austria
|
|-
| [http://brmlab.cz brmlab, prague hackerspace]
| 14th Nov 2011
28th Nov 2011
([http://brmlab.cz/event/bitcoin_seminar])
| [http://brmlab.cz/place Brmlab, Bubenska 1]
| brmlab crew, slush, genjix
|
|-
| [http://www.facebook.com/groups/175596065827848/ Bitcoin Boston]
| Bi-weekly on Saturday or Sunday ([http://www.facebook.com/groups/175596065827848/ See Facebook page])
| Starbucks, Harvard Square
| Anyone who wants to come!
| So far our meetings have been pretty sporadic, but we hope to gain some regularity soon...
|-
| [http://www.meetup.com/bitcoin New York Bitcoin Users]
| 6:00 PM, 3rd Sunday of every month ([http://www.meetup.com/bitcoin/events/past past meetings])
| OnlyOneTV Studios - 290 Fifth Ave New York, NY
| Bruce Wagner (Organizer) and others
|
|-
|-
| [http://www.meetup.com/bitcoin New York Bitcoin Users]
| 6:00 PM, every Wednesday of every month ([http://www.meetup.com/bitcoin/events/past past meetings])
| Just Sweet Dessert House - 83 Third Ave New York, NY
| Yifu Guo (Organizer) and crew
| hosted by Bitsyncom, the people behind [[Bitnavigator]], walk-ins welcome;
|-
| [http://www.meetup.com/PhillyBitcoin Philadelphia Bitcoin User Group]
| TBD
| TBD
| Brian Cohen (Organizer) and others
|
|-
| [http://www.meetup.com/BitcoinDC Washington, DC Bitcoin Users]
| 7:00 PM, 1st Monday of every month ([http://www.meetup.com/BitcoinDC/#past past meetings])
| Northside Social, 3211 Wilson Blvd Arlington, VA
| [[User:Dduane|Darrell Duane]] (Organizer) and others
|
|-
| [http://www.meetup.com/Silicon-Valley-Bitcoin-Users Silicon Valley Bitcoin Users]
| 7:00 PM, Tuesday, June 14, 2011 ([http://www.meetup.com/Silicon-Valley-Bitcoin-Users/events/past past meetings])
| 140B S Whisman Road Mountain View, CA
| Brian Mcqueen and others
|
|-
| [http://www.meetup.com/BitcoinChicago Chicago]
| No regular schedule yet ([http://www.meetup.com/BitcoinChicago/events/past past meetings])
| Sunnyvale Art Gallery Cafe, 251 W El Camino Real Sunnyvale, CA
| Igor
|
|-
| [http://www.meetup.com/denver-bitcoin Denver]
| First meeting June 4th, 2011 ([http://www.meetup.com/denver-bitcoin/events/past past meetings])
| Gypsy House Cafe - 1279 Marion St Denver, CO
| bearbones
|
|-
| [http://www.meetup.com/bitcoinSF Bitcoin SF]
| Saturday, June 4, 2011 ([http://www.meetup.com/bitcoinSF past meetings])
| SFSU - 1600 Holloway Ave. San Francisco, CA
| Brian Mcqueen and others
|
|-
| [http://www.meetup.com/Los-Angeles-Digital-Currency-Innovators-Group Los Angeles Digital Currency Innovators]
| Thursday July 7th, 2011, 7 PM
| (mt)/Media Temple, Culver City, CA
| [[User:sgornick|Stephen Gornick]] (Interim organizer) and others
| Seeking meetup coordinator
|-
| [http://www.meetup.com/Las-Vegas-Bitcoin-Users Las Vegas Bitcoin Users]
| Monthly, check calendar ([http://www.meetup.com/Las-Vegas-Bitcoin-Users/#upcomming meetings])
| Putters, 6945 South Rainbow Boulevard, Las Vegas, NV
| Mark Russell, Julian Tosh
|
|-
| [http://www.meetup.com/Bitcoin-Twin-Cities-Users-Meetup Bitcoin Twin Cities Users]
| Friday, June 10, 2011, 6:30 PM
| Joule - 1200 Washington Ave S Minneapolis, MN
| Mac Manson
|
|-
| [http://www.meetup.com/Portland-Bitcoin-Meetup-Users Portland Bitcoin Users Meetup Group]
| forming
|
| Steven Wagner
|
|-
| [http://www.meetup.com/Bitcoin-Orlando Bitcoin Orlando]
| ([http://www.meetup.com/Bitcoin-Orlando#past past meetings])
| Frank & Steins 150 S. Magnolia Ave, Orlando, FL
| Antonio Gallippi
|
|-
| [http://www.hive13.org/?p=310 Hive13 Hackerspace]
| Bitcoin Exchange, Every Tuesday, 7:30 PM
| Hive13 - 2929 Spring Grove Avenue, Cincinnati, OH
|
|
|-
| [[Melbourne Bitcoin Community]]
| Forming
| Suggest a location, and a date and time
| @da2ce7 on Freenode Channel: #bitcoin-aus
|
|-
| [[Bitcoin:Tokyo meetup|Tokyo]]
|
|
| [[User:MagicalTux|Magical Tux]] (Organizer) and others
|
|-
| [http://meetup.com/Bitcoin-Canada Vancouver Canada]
| ([http://www.meetup.com/Bitcoin-Canada/#past past meetings])
| The Brickhouse - 730 Main St.
| humble (and others)
|
|-
| [http://www.bitcoin.org/smf/index.php?topic=6725.0 Zurich Switzerland]
| Semi-regular, about once a month
| Oliver Twist Pub
| Stefan Thomas (weusecoins), Mike Hearn (bitcoinj), bitdragon, Luzius (Wuala), more ...
|
|-
| Seattle Bitcoin Meetup
| [http://www.meetup.com/SeattleBitCoin/ Semi-regularly].
| [http://maps.google.com/maps?q=cafe+solstice&daddr=4116+University+Way,+Seattle,+WA+98105-6214&hl=en&ll=47.657424,-122.31313&spn=0.007328,0.01929&gl=us&view=map&geocode=CRT9Bdg7zX3vFdcx1wIdWqa1-CFcJ9qrr9CcEQ&t=h&z=16 Solstice Cafe, 2pm]
| [https://bitcointalk.org/index.php?action=profile;u=36217 indolering]
|
|-
| [https://bitcointalk.org/index.php?topic=42262.0 Munich Germany]
| Semi-regular, about once a month
| Optimolwerke
|
|
|-
| [http://www.meetup.com/bitcoin-il/ Israel Bitcoin Meetup Group]
| Occasional
| TBD
| Meni Rosenfeld
|
|-
|}

==See Also==

* [http://hackerspaces.org/wiki/List_of_Hacker_Spaces List of Hacker Spaces]

[[Category:Local]]

[[de:Treffen]]

Change

2011-11-08T08:25:08Z

Holy-Fire: +categories

When the output of a transaction is used as the input of another transaction, it must be spent in its entirety. Sometimes the coin value of the output is higher than what the user wishes to pay. In this case, the client generates a new Bitcoin address, and sends the difference back to this address. This is known as [[change]].

The wallet file contains the private keys for change addresses, and they can receive and send coins normally. However, the GUI in the default client does not display them in the address book.

[[Category:Technical]]
[[Category:Vocabulary]]

Transaction

2011-11-08T08:20:07Z

Holy-Fire: Link change

[[File:TxBinaryMap.png|thumb|right|Byte-map of Transaction with each type of TxIn and TxOut]]
A transaction is a signed section of data that is broadcast to the [[network]] and collected into [[block|blocks]]. They reference a previous transaction and dedicate a certain number of bitcoins from it to a new public key (Bitcoin address). They are not encrypted (nothing in Bitcoin is encrypted).

A [[block chain browser]] is a site where every transaction included within the block chain can be viewed. This is useful for seeing the technical details of transaction in action, and for payment verification purposes.

=== Example Bitcoin Transaction ===

==== Data ====

<pre>Input:
Previous tx: f5d8ee39a430901c91a5917b9f2dc19d6d1a0e9cea205b009ca73dd04470b9a6
Index: 0
scriptSig: 304502206e21798a42fae0e854281abd38bacd1aeed3ee3738d9e1446618c4571d10
90db022100e2ac980643b0b82c0e88ffdfec6b64e3e6ba35e7ba5fdd7d5d6cc8d25c6b241501

Output:
Value: 5000000000
scriptPubKey: OP_DUP OP_HASH160 404371705fa9bd789a2fcd52d2c580b65d35549d
OP_EQUALVERIFY OP_CHECKSIG</pre>

==== Explanation ====

The input in this transaction imports 50 BTC from output #0 in transaction f5d8... Then the output sends 50 BTC to a Bitcoin address (expressed here in hexadecimal 4043... instead of the normal base58). When the recipient wants to spend this money, he will reference output #0 of this transaction in an input of his own transaction.

===== Input =====

An '''input''' is a reference to an output in a different transaction. Multiple inputs are often listed in a transaction. The values of the referenced outputs are added up, and the total is usable in the outputs of this transaction. '''Previous tx''' is a [[hash]] of a previous transaction. '''Index''' is the specific output in the referenced transaction. '''ScriptSig''' is the first half of a [[script]] (discussed in more detail later).

The script contains two components, a signature and a public key. The public key belongs to the redeemer of the output transaction and proves the creator is allowed to redeem the outputs value. The other component is an ECDSA signature over a hash of a simplified version of the transaction. It, combined with the public key, proves the transaction was created by the real owner of the address in question. Various flags define how the transaction is simplified and can be used to create different types of payment.

===== Output =====

An '''output''' contains instructions for sending bitcoins. '''Value''' is the number of Satoshi (1 BTC = 100,000,000 Satoshi) that this output will be worth when claimed. '''ScriptPubKey''' is the second half of a script (discussed later). There can be more than one output, and they share the combined value of the inputs. Because an output can only ever be referenced by a single input, the entire combined input value needs to be sent in an output if you don't want to lose it. If the input is worth 50 BTC but you only want to send 25 BTC, Bitcoin will create two outputs worth 25 BTC: one to the destination, and one back to you (known as "[[change]]", though you send it to yourself). Any input bitcoins not redeemed in an output is considered a [[transaction fee]]; whoever generates the block will get it.
[[File:transaction.png|thumb|A sends 100 BTC to C and C generates 50 BTC. C sends 101 BTC to D, and he needs to send himself some change. D sends the 101 BTC to someone else, but they haven't redeemed it yet. Only D's output and C's change are capable of being spent in the current state.]]

===== Verification =====

To verify that inputs are authorized to collect the values of referenced outputs, Bitcoin uses a custom Forth-like [[script|scripting]] system. The input's scriptSig and the ''referenced'' output's scriptPubKey are evaluated (in that order), with scriptPubKey using the values left on the stack by scriptSig. The input is authorized if scriptPubKey returns true. Through the scripting system, the sender can create very complex conditions that people have to meet in order to claim the output's value. For example, it's possible to create an output that can be claimed by anyone without any authorization. It's also possible to require that an input be signed by ten different keys, or be redeemable with a password instead of a key.

=== Types of Transaction ===
Bitcoin currently only creates three different scriptSig/scriptPubKey pairs. These are described below.

It is possible to design more complex types of transactions, and link them together into cryptographically enforced agreements. These are known as [[Contracts]].

==== Transfer to IP address ====

scriptPubKey: <pubKey> OP_CHECKSIG
scriptSig: <sig>
The sender gets the public key when talking to the recipient over IP. When redeeming coins that have been sent to an IP address, the recipient provides only a signature. The signature is checked against the public key in scriptPubKey.

Checking process:
{| class="wikitable"
|-
! Stack
! Script
! Description
|-
|Empty.
|<sig> <pubKey> OP_CHECKSIG
|scriptSig and scriptPubKey are combined.
|-
|<sig> <pubKey>
| OP_CHECKSIG
|Constants are added to the stack.
|-
|true
|Empty.
|Signature is checked for top two stack items.
|}

==== Transfer to Bitcoin address ====

scriptPubKey: OP_DUP OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG
scriptSig: <sig> <pubKey>
A Bitcoin [[address]] is only a hash, so the sender can't provide a full public key in scriptPubKey. When redeeming coins that have been sent to a Bitcoin address, the recipient provides both the signature and the public key. The script verifies that the provided public key does hash to the hash in scriptPubKey, and then it also checks the signature against the public key.

Checking process:
{| class="wikitable"
|-
! Stack
! Script
! Description
|-
|Empty.
| <sig> <pubKey> OP_DUP OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG
| scriptSig and scriptPubKey are combined.
|-
|<sig> <pubKey>
| OP_DUP OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG
| Constants are added to the stack.
|-
|<sig> <pubKey> <pubKey>
| OP_HASH160 <pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG
| Top stack item is duplicated.
|-
|<sig> <pubKey> <pubHashA>
|<pubKeyHash> OP_EQUALVERIFY OP_CHECKSIG
| Top stack item is hashed.
|-
|<sig> <pubKey> <pubHashA> <pubKeyHash>
|OP_EQUALVERIFY OP_CHECKSIG
| Constant added.
|-
|<sig> <pubKey>
|OP_CHECKSIG
| Equality is checked between the top two stack items.
|-
|true
|Empty.
|Signature is checked for top two stack items.
|}

==== Generation ====

Generations have a single input, and this input has a "coinbase" parameter instead of a scriptSig. The data in "coinbase" can be anything; it isn't used. Bitcoin puts the current compact-format [[target]] and the arbitrary-precision "extraNonce" number there, which increments every time the Nonce field in the [[block_hashing_algorithm|block header]] overflows. Outputs can be anything, but Bitcoin creates one exactly like an IP address transaction.

[[Category:Technical]]
[[Category:Vocabulary]]
[[de:Transaktion]]
[[pl:Transakcje]]

Change

2011-11-08T08:19:10Z

Holy-Fire: Stub

Selling bitcoins

2011-08-04T18:20:55Z

Holy-Fire: /* Fixed Rate Exchanges & Others */ + Bitcoil

==Major Exchanges==
The best rates for selling medium to large amounts of bitcoins generally when withdrawing from an exchange using a cash method such as a bank transfer (ACH, EUR/SEPA).

{| class="wikitable"
|-
| Exchange || Type || Adding Funds || Withdrawing Funds || [[eWallet]] || Notes
|-
| [[MtGox]] || Market || BTC USD ([[Dwolla]]) USD (International bank wire) USD (Wire to [[AurumXChange Company|AurumXChange]]) EUR (SEPA bank transfer) AUD (Bank wire) GBP (Bank wire) Liberty Reserve USD || BTC USD ([[Dwolla]]) USD (Wire via [[AurumXChange Company|AurumXChange]]) USD (Check via [[Paxum]]) USD (ATM via [[Paxum]]) USD (wire via [[Paxum]]) EUR (SEPA bank transfer) AUD (Bank wire) Liberty Reserve USD Liberty Reserve USD (via AurumXChange) || {{Table Value Yes}} || Restrictions and limits on withdrawals.
|-
| [[Camp BX]] || Market || BTC USD (Dwolla) || BTC USD (Dwolla) || {{Table Value Yes}} || Atlanta - USA based, security certification from McAfee, provides advanced trading options with AON/FOK/Market, Short Selling coming soon, Trading API available; Dwolla only.
|-
| [[TradeHill]] || Market || BTC USD (Domestic bank wire) USD (International bank wire) USD (Check via [[Paxum]]) USD (wire via [[Paxum]]) EUR (SEPA bank transfer) CLP (Bank transfer) PEN (Bank transfer) INR (Bank transfer) AUD (Bank transfer) Liberty Reserve USD || BTC USD (Dwolla) USD (Domestic bank wire) USD (International bank wire) USD (Direct deposit / ACH) USD (Check via [[Paxum]]) USD (ATM via [[Paxum]]) USD (Prepaid card via [[Paxum]]) EUR (SEPA bank transfer) CLP (Bank transfer) INR (Bank transfer) AUD (Bank transfer) Liberty Reserve USD || {{Table Value Yes}} ||
|-
| [[Bitomat]] || Market || BTC PLN (Bank transfer) || BTC PLN (Bank transfer) || {{Table Value Yes}} ||
|-
| [[Britcoin]] || Market || BTC GBP (bank deposit) || BTC GBP (bank deposit) || {{Table Value Yes}} ||
|-
| [[Intersango]] || Market || BTC EUR (SEPA bank deposit) || BTC EUR (SEPA bank transfer) || {{Table Value Yes}} ||
|-
| [[Intersango.us]] || Market || BTC USD (Dwolla) USD (Domestic bank wire) USD (ACH) || BTC USD (Dwolla) || {{Table Value Yes}} ||
|-
| [[ExchangeBitcoins.com]] || Market || BTC USD ([[Popmoney]]) USD (ING Person2Person) USD (Bank wire) USD (Check) || BTC USD (Dwolla) USD (Check) || {{Table Value Yes}} ||
|-
| [[Bitcoin7]] || Market || BTC EUR (Bank transfer) USD (Domestic wire) USD (International wire) Liberty Reserve USD Liberty Reserve EUR BGN (Bank transfer) || BTC EUR (Bank transfer) USD (Dwolla) USD (Bank transfer) Liberty Reserve USD PLN (Bank transfer) SAR (Bank transfer) BGN (ePay) BGN (Bank transfer) || {{Table Value Yes}} || USD wire to Citibank. EUR transfers to/from FiBank.
|-
| [[VirtEx]] || Market || BTC CAD (Interac) CAD (online bill pay) CAD (cash at TDBank) || BTC CAD (Interac) CAD (direct deposit) CAD (Prepaid VISA) || {{Table Value Yes}} ||
|-
| [[VirWoX]] || Market || BTC SLL (Second Life) ACD (Avination) OMC (OpenSim) USD,EUR,GBP,CHF ([[PayPal]]) USD,EUR,GBP (Credit & Debit cards via [[Moneybookers]]) USD,EUR,GBP ([[NETELLER]]) EUR (DIRECTebanking / Sofortüberweisung) USD,EUR,GBP,CHF ([[paysafecard]]) EUR (SEPA bank transfer) || BTC SLL (Second Life) ACD (Avination) OMC (OpenSim) USD,EUR,GBP,CHF ([[PayPal]]) USD,EUR,GBP ([[Moneybookers]]) USD,EUR,GBP ([[NETELLER]]) EUR (SEPA bank transfer) || {{Table Value Yes}} || Trading through Second Life Linden Dollars (highly liquid). Variable limits on PayPal and Credit Card deposits.
|-
| [[WM-Center]] || Exchanger || BTC USD (International bank wire, Western Unon, Moneygram, Xoom etc, cash) EUR (IBAN bank wire) RUB (bank wire, WU, Anelik and etc, cash) AUD (Bank wire) Liberty Reserve USD/EUR, Perfect Money USD/EUR, Pecunix, Paxum, c-gold, Hoopay, GDP || BTC USD (International bank wire, Western Unon, Moneygram, Xoom etc, cash) EUR (IBAN bank wire) RUB (bank wire, WU, Anelik and etc, cash) AUD (Bank wire) Liberty Reserve USD/EUR, Perfect Money USD/EUR, Pecunix, Paxum, c-gold, Hoopay, GDP PayPal USD/EUR, Moneybookers, Neteller || {{Table Value No}} || 24/7/365 support in english, spanish and russian!
|}

==Fixed Rate Exchanges & Others==

The following exchanges are either exchanges using a fixed rate based on other markets or are exchanges that enable you to redeem smaller amounts of bitcoins at reasonable rates:

* [[Bitcoin Market]] Trade your BTCs for MoneyBookers, Liberty Reserve or Pecunix.
* [[BitMarket.eu]] Trade your BTCs for EUR, GBP and PLN (SEPA bank transfer). OTC with Escrow.
* [[Bitcoiny.cz]] Trade your BTCs for CZK. No-escrow, direct person-to-person trading.
* [[Bit]] / BTC China - Market for exchanging bitcoins to and from CNY.
* [[bitcoin-otc]] IRC trading marketplace will usually have people willing to deal for small and larger amounts using various payment methods, including [[PayPal]], [[Dwolla]], [[Linden Dollars]], etc.
* [[BitcoinExchange Services]] - Cash out your Bitcoins to MoneyGram, Western Union, prepaid debit cards, Visa gift cards, or gift cards to ALL major businesses, retail shops, restaurants, hotels, etc.
* [[Lilion Transfer]] Exchanges bitcoins for Liberty Reserve, [[Pecunix]], [[AlertPay]], [[Moneybookers]], [[PayPal]], and more.
* [[Nanaimo Gold]] Redeem bitcoins for Liberty Reserve (automated) or for money transfer, money order or direct deposit within Canada.
* [[Bitcoin Morpheus]] purchase reloadable debit cards with bitcoins
* [[Bitcoin Argentina]] Trades BTC for ARS. Cash and bank transfer. No exchange fees.
* [[Bahtcoin]] Trade BTC for Thai Baht, cash, LR, Webmoney, or Thai mobile and gaming prepaid cards.
* [[Bitcoin Brasil]] Cash exchange that redeems bitcoins for BRL, USD.
* [[Bitcoin.com.es]] Trade your BTCs for EUR (Bank transfer).
* [[BitPiggy]] Trade your BTCs for AUD (Bank transfer).
* [[GetBitcoin]] Trade your BTCs for USD (Cash, Check or Bank Wire).
* [[Bitcoin2Cash]] Redeems bitcoins with cash mailed to you
* [[Bitcoin 2 Credit Card]] purchase virtual VISA prepaid cards with bitcoins
* [[Bitcoin 4 Cash]] Redeems bitcoins with cash mailed to you
* [[Bitcoin Cashout]] purchase virtual prepaid cards with bitcoins
* [[btcbuy|BTC Buy]] Simple interface to trade your BTCs for Amazon, Buy.com, NewEgg, and Walmart gift cards
* [[bitcoin.local]] arranges for exchanging currencies in person with someone nearby
* [[Ubitex]] In-person exchange
* [[Bitcoil]] Exchange BTC for ILS with bank transfers in Israel

==See Also==

* [[:Category:Digital currencies|Digital currencies]]
* [[Buying bitcoins]]
* [[Secure Trading]]
* [[Comparison of exchanges]]

Buying bitcoins

2011-08-04T18:19:15Z

Holy-Fire: /* Fixed Rate Exchanges & Others */ + Bitcoil

One issue currently facing a newcomer to bitcoin is, how do I get some? While there is the [[bitcoin faucet]] that can get you started with a small fraction of a coin, when getting larger amounts the user faces an abundance of choice. This page will cut through the clutter, and help direct you to the right exchanger for your needs.

==Major Exchanges==

The least expensive methods for buying bitcoins involve transferring funds using a bank wire, ACH, bank transfer (ACH, EUR / SEPA).

{| class="wikitable"
|-
| Exchange || Type || Adding Funds || Withdrawing Funds || [[eWallet]] || Notes
|-
| [[MtGox]] || Market || BTC USD ([[Dwolla]]) USD (International bank wire) USD (Wire to [[AurumXChange Company|AurumXChange]]) EUR (SEPA bank transfer) AUD (Bank wire) GBP (Bank wire) Liberty Reserve USD || BTC USD ([[Dwolla]]) USD (Wire via [[AurumXChange Company|AurumXChange]]) USD (Check via [[Paxum]]) USD (ATM via [[Paxum]]) USD (wire via [[Paxum]]) EUR (SEPA bank transfer) AUD (Bank wire) Liberty Reserve USD Liberty Reserve USD (via AurumXChange) || {{Table Value Yes}} || Restrictions and limits on withdrawals.
|-
| [[Camp BX]] || Market || BTC USD (Dwolla) || BTC USD (Dwolla) || {{Table Value Yes}} || Atlanta - USA based, security certification from McAfee, provides advanced trading options with AON/FOK/Market, Short Selling coming soon, Trading API available; Dwolla only.
|-
| [[TradeHill]] || Market || BTC USD (Domestic bank wire) USD (International bank wire) USD (Check via [[Paxum]]) USD (wire via [[Paxum]]) EUR (SEPA bank transfer) CLP (Bank transfer) PEN (Bank transfer) INR (Bank transfer) AUD (Bank transfer) Liberty Reserve USD || BTC USD (Domestic bank wire) USD (International bank wire) USD (Direct deposit / ACH) USD (Check via [[Paxum]]) USD (ATM via [[Paxum]]) USD (Prepaid card via [[Paxum]]) EUR (SEPA bank transfer) CLP (Bank transfer) INR (Bank transfer) AUD (Bank transfer) Liberty Reserve USD || {{Table Value Yes}} ||
|-
| [[Bitomat]] || Market || BTC PLN (Bank transfer) || BTC PLN (Bank transfer) || {{Table Value Yes}} ||
|-
| [[Britcoin]] || Market || BTC GBP (bank deposit) || BTC GBP (bank transfer) || {{Table Value Yes}} ||
|-
| [[Intersango]] || Market || BTC EUR (SEPA bank deposit) || BTC EUR (SEPA bank transfer) || {{Table Value Yes}} ||
|-
| [[Intersango.us]] || Market || BTC USD (Dwolla) USD (Domestic bank wire) USD (ACH) || BTC USD (Dwolla) || {{Table Value Yes}} ||
|-
| [[ExchangeBitcoins.com]] || Market || BTC USD ([[Popmoney]]) USD (ING Person2Person) USD (Bank wire) USD (Check) || BTC USD (Dwolla) USD (Check) || {{Table Value Yes}} ||
|-
| [[Bitcoin7]] || Market || BTC EUR (Bank transfer) USD (Domestic wire) USD (International wire) Liberty Reserve USD Liberty Reserve EUR BGN (Bank transfer) || BTC EUR (Bank transfer) USD (Dwolla) USD (Bank transfer) Liberty Reserve USD PLN (Bank transfer) SAR (Bank transfer) BGN (ePay) BGN (Bank transfer) || {{Table Value Yes}} || USD wire to Citibank. EUR transfers to/from FiBank.
|-
| [[VirtEx]] || Market || BTC CAD (Interac) CAD (online bill pay) CAD (cash at TDBank) || BTC CAD (Interac) CAD (direct deposit) CAD (Prepaid VISA) || {{Table Value Yes}} ||
|-
| [[VirWoX]] || Market || BTC SLL (Second Life) ACD (Avination) OMC (OpenSim) USD,EUR,GBP,CHF ([[PayPal]]) USD,EUR,GBP (Credit & Debit cards via [[Moneybookers]]) USD,EUR,GBP ([[NETELLER]]) EUR (DIRECTebanking / Sofortüberweisung) USD,EUR,GBP,CHF ([[paysafecard]]) EUR (SEPA bank transfer) || BTC SLL (Second Life) ACD (Avination) OMC (OpenSim) USD,EUR,GBP,CHF ([[PayPal]]) USD,EUR,GBP ([[Moneybookers]]) USD,EUR,GBP ([[NETELLER]]) EUR (SEPA bank transfer) || {{Table Value Yes}} || Trading through Second Life Linden Dollars (highly liquid). Variable limits on PayPal and Credit Card deposits.
|-
| [[WM-Center]] || Exchanger || BTC USD (International bank wire, Western Unon, Moneygram, Xoom etc, cash) EUR (IBAN bank wire) RUB (bank wire, WU, Anelik and etc, cash) AUD (Bank wire) Liberty Reserve USD/EUR, Perfect Money USD/EUR, Pecunix, Paxum, c-gold, Hoopay, GDP || BTC USD (International bank wire, Western Unon, Moneygram, Xoom etc, cash) EUR (IBAN bank wire) RUB (bank wire, WU, Anelik and etc, cash) AUD (Bank wire) Liberty Reserve USD/EUR, Perfect Money USD/EUR, Pecunix, Paxum, c-gold, Hoopay, GDP PayPal USD/EUR, Moneybookers, Neteller || {{Table Value No}} || 24/7/365 support in english, spanish and russian!
|}

==Fixed Rate Exchanges & Others==

For smaller amounts, the options are limited due to bank transfer fees, conversion fees and transaction size restrictions. Options include:

{| class="wikitable"
|-
| Service || Type || Payment Method || Notes
|-
| [[Bitcoin Market]] || Market || USD (Liberty Reserve) USD (MoneyBookers) GAU (Pecunix) || Varies (person to person)
|-
| [[BitMarket.eu]] || Market || EUR GBP USD PLN (Polish złoty) RUB || Varies (person to person)
|-
| [[Bitcoiny.cz]] || Market || CZK || Varies (person to person)
|-
| [[Bit]] / BTC China || Market || n/a || n/a
|-
| [[Bitfunnel]] || Credit Card payment exchange/brokering services || Varies (person to person)
|-
| [[bitcoin-otc|#bitcoin-otc]] || [http://bitcoin-otc.com/vieworderbook.php Order Book] || Varies (person to person) || IRC trading marketplace will usually have people willing to deal for small and larger amounts using various payment methods, including [[PayPal]], [[Dwolla]], [[Linden Dollars]], etc.
|-
| [[BitcoinExchange Services]] || Fixed Rate || Cash USD, [[MoneyPak]], LR, MoneyGram, Western Union, [[Pecunix]] || Selling BTC/MtGoxUSD/LR - Will cash out to [[Dwolla]], wire transfer, ACH, MoneyGram, Western Union
|-
| [[Lilion Transfer]] || Fixed Rate || USD (Liberty Reserve) [[Pecunix]] ||
|-
| [[Nanaimo Gold]] || Fixed Rate || USD (Liberty Reserve) Western Union money transfer Moneygram money transfer Cash in the mail || LR <--> Bitcoin exchange is automated For cash in the mail send USD, EUR, CAD, or GBP. Canada mailing address.
|-
| [[Bitcoin Morpheus]] || Fixed Rate || Cash, check or money order through the mail || U.S. mailing address for cash transactions.
|-
| [[Bitcoin Argentina]] || Fixed Rate || Cash: ARS, BRL, USD Bank transfer: ARS || No exchange fees!
|-
| [[Bitcoin.com.es]] || Fixed Rate || EUR (bank deposit) || Bank transfer or cash deposits at OpenBank in Spain.
|-
| [[Bahtcoin]] || Fixed Rate || Cash, Webmoney Liberty Reserve USD || Will cash out to Thai mobile and gaming prepaid cards as well.
|-
| [[Bitcoin Brasil]] || Fixed Rate || BRL (Brazilian Real) USD || Cash exchange
|-
| [[BitPiggy]] || Fixed Rate || AUD (Australian Dollar)|| Payment via bank transfer.
|-
| [[GetBitcoin]] || Fixed Rate || USD (Dwolla) USD (Bank wire) USD (Cash in the mail) USD (Money Order) USD (Cashier's Check/Certified Check) USD (Western Union) USD (Traveler's Check) USD (Prepaid Debit Card) || For cash in mail, send USD. U.S. mailing address.
|-
| [[Bitcoin 4 Cash]] || Fixed Rate || Cash in the mail || Send USD or CAD. Canada mailing address.
|-
| [[Bitcoin2Cash]] || Fixed Rate || Cash in the mail || Send USD. U.S. mailing address.
|-
| [[bitcoin.local]] || Directory || Varies (person to person) ||
|-
| [[YouTipIt]] || Fixed Rate || USD EUR GBP || Purchase bitcoins to add to your balance with YouTipIt using credit card through ClickAndBuy.
|-
| [[Ubitex]] || In person exchange || Varies (person to person) ||
|-
| [[Bitcoil]] || Fixed Rate || ILS (bank transfer) ||
|}

==Other Financial Services==

{| class="wikitable"
|-
| Service || Type || Payment || Settled || Notes
|-
| [http://polimedia.us/bitcoin/options.php Derivatives] || Buy / Sell / Exercise CALLs / PUTs, American style. 52 strikes offered (by .5), current month + 2. No shorting available yet.|| BTC || BTC || Transactions encoded via amt. Must use non-rounding client (0.3.24 or later)
|}

==See Also==

* [[:Category:Digital_currencies|Digital Currencies]]
* [[Selling bitcoins]]
* [[Secure Trading]]
* [[Comparison of exchanges]]
* [[:Category:Local|Local]] exchanges

[[Category:Exchanges]]
[[Category:Introduction]]
[[zh-cn:购买bitcoins]]

Bitcoil

2011-08-04T14:49:30Z

Holy-Fire: Never stopped being an exchange, only temporarily suspended. Sorry for the unclear announcement.

A [[currency exchange|exchange]] allowing trade between bitcoins and ILS (Israeli New Shekels).

Purchases of bitcoins and proceeds from redemptions are transferred through an Israeli bank. Each trade incurs a 5 ILS fee.

==History==
The exchange was announced on April 13th, 2011<ref>[http://www.bitcoin.org/smf/index.php?topic=5762.0 Bitcoil - Exchange bitcoins for ILS]</ref>. On June 30, 2011 the site closed down temporarily, and relaunched on August 1, 2011.

==See Also==

* [[Buying bitcoins]]
* [[Selling bitcoins]]

==External Links==

* [http://bitcoil.co.il Bitcoil] exchange website

==References==
<references/>
[[Category:Exchanges]]

Bitcoil

2011-08-04T12:18:42Z

Holy-Fire: It was never meant to be "instead". + It's now relaunched

Help:FAQ

2011-06-23T08:54:42Z

Holy-Fire: /* I've been mining for a long time and haven't created any new Bitcoins. What's wrong? */

Here you will find answers to the most commonly asked questions.

== General ==
=== What are bitcoins? ===
Bitcoins are the unit of currency of the Bitcoin system. A commonly used shorthand for this is “BTC” to refer to a price or amount (eg: “100 BTC”).
A Bitcoin isn't tangible. It is just a number associated with a [[Address|Bitcoin Address]]. See also an [[Introduction|easy intro]] to bitcoin.

=== How can I get Bitcoins? ===

There are five ways to get Bitcoins:

* There are several services where you can [[buying bitcoins|trade them]] for “real” money.
* Accept Bitcoins as payment for goods or services.
* Find a local trader on [http://tradebitcoin.com tradebitcoin] (or somewhere else) and trade with him in cash.
* Create a new [[block]] (currently yields 50 Bitcoins).
* Participate in a [[Pooled mining|mining pool]].

=== Can I buy Bitcoins with Paypal? ===

While it's possible to find an individual who wishes to sell Bitcoin to you via Paypal, (perhaps via [http://www.bitcoin-otc.com/ #bitcoin-otc] ) most major exchanges do not allow funding through Paypal. This is due to repeated cases where someone pays for Bitcoins with Paypal, receives their Bitcoins, and then fraudulently complains to Paypal that they never received their goods. Paypal too often sides with the fraudulent buyer in this case, and so exchangers no longer allow this method of funding.

Buying Bitcoins from individuals with this method is still possible, but requires mutual trust. In this case, Bitcoin seller beware.

=== How are new Bitcoins created? ===

[[File:total_bitcoins_over_time_graph.png|thumb|Number of bitcoins over time, assuming a perfect 10-minute interval.]]
New coins are generated by a network node each time it finds the solution to a certain mathematical problem (i.e. creates a new [[block]]), which is difficult to perform and can demonstrate a [[proof of work]]. The reward for solving a block is [[controlled inflation|automatically adjusted]] so that in the first 4 years of the Bitcoin network, 10,500,000 BTC will be created. The amount is halved each 4 years, so it will be 5,250,000 over years 4-8, 2,625,000 over years 8-12 and so on. Thus the total number of coins will approach 21,000,000 BTC over time.

In addition, built into the network is a system that attempts to allocate new coins in blocks about every 10 minutes, on average, somewhere on the network. As the number of people who attempt to generate these new coins changes, the difficulty of creating new coins changes. This happens in a manner that is agreed upon by the network as a whole, based upon the time taken to generate the previous 2016 blocks. The difficulty is therefore related to the average computing resources devoted to generate these new coins over the time it took to create these previous blocks. The likelihood of somebody "discovering" one of these blocks is based on the computer they are using compared to all of the computers also generating blocks on the network.

=== What's the current total number of Bitcoins in existence? ===

[http://blockexplorer.com/q/totalbc Current count]

The number of blocks times the coin value of a block is the number of coins in existence. The coin value of a block is 50 BTC for each of the first 210,000 blocks, 25 BTC for the next 210,000 blocks, then 12.5 BTC, 6.25 BTC and so on.

=== How divisible are Bitcoins? ===

Technically, a Bitcoin can be divided down to 8 decimals using existing data structures, so 0.00000001 BTC is the smallest amount currently possible. Discussions about and ideas for ways to provide for even smaller quantities of Bitcoins may be created in the future if the need for them ever arises.

=== What do I call the various denominations of Bitcoins? ===

There is a lot of discussion about the naming of these fractions of Bitcoins. The leading candidates are:

* 1 BTC = 1 Bitcoin
* 0.01 BTC = 1 cBTC = 1 Centi-Bitcoin (also referred to as Bitcent)
* 0.001 BTC = 1 mBTC = 1 Milli-Bitcoin (also referred to as mbit (pronounced em-bit) or millibit)
* 0.000 001 BTC = 1 μBTC = 1 Micro-Bitcoin (also referred to as ubit (pronounced yu-bit) or microbit)

The above follows the accepted international SI units for thousandths, millionths and billionths. There are many arguments against the special case of 0.01 BTC since it is unlikely to represent anything meaningful as the Bitcoin economy grows (it certainly won't be the equivalent of 0.01 USD, GBP or EUR). Equally, the inclusion of existing national currency denominations such as "cent", "nickel", "dime", "pence", "pound", "kopek" and so on are to be discouraged. This is a worldwide currency.

One exception is the "satoshi" which is smallest denomination currently possible

* 0.000 000 01 BTC = 1 Satoshi (pronounced sa-toh-shee)

which is so named in honour of Satoshi Nakamoto the pseudonym of the inventor of Bitcoin.

For an overview of all defined units of Bitcoin (including less common and niche units), see [[Units]].

Further discussion on this topic can be found on the forums here:

* [http://forum.bitcoin.org/index.php?topic=14438.msg195287#msg195287 We need names]
* [http://forum.bitcoin.org/index.php?topic=8282.0 What to call 0.001 BTC]

=== How does the halving work when the number gets really small? ===

The reward will go from 0.00000001 BTC to 0. Then no more coins will likely be created.

The calculation is done as a right bitwise shift of a 64-bit signed integer, which means it is divided by 2 and rounded down. The integer is equal to the value in BTC * 100,000,000. This is how all Bitcoin balances/values are stored internally.

Keep in mind that using current rules this will take nearly 100 years before it becomes an issue and Bitcoins may change considerably before that happens.

=== How long will it take to generate all the coins? ===

The last block that will generate coins will be block #6,929,999. This should be generated around year 2140. Then the total number of coins in circulation will remain static at 20,999,999.9769 BTC.

Even if the allowed precision is expanded from the current 8 decimals, the total BTC in circulation will always be slightly below 21 million (assuming everything else stays the same). For example, with 16 decimals of precision, the end total would be 20999999.999999999496 BTC.

=== If no more coins are going to be generated, will more blocks be created? ===

Absolutely! Even before the creation of coins ends, the use of [[transaction fee|transaction fees]] will likely make creating new blocks more valuable from the fees than the new coins being created. When coin generation ends, what will sustain the ability to use bitcoins will be these fees entirely. There will be blocks generated after block #6,929,999, assuming that people are still using Bitcoins at that time.

=== But if no more coins are generated, what happens when Bitcoins are lost? Won't that be a problem? ===

Not at all. Because of the law of supply and demand, when fewer Bitcoins are available the ones that are left will be in higher demand, and therefore will have a higher value. So when Bitcoins are lost, the remaining Bitcoins will increase in value to compensate. As the value of Bitcoins increase, the number of Bitcoins required to purchase an item '''de'''creases. This is known as a [[Deflationary spiral|deflationary economic model]]. Eventually, if and when it gets to the point where the largest transaction is less than 1BTC, then it's a simple matter of shifting the decimal place to the right a few places, and the system continues.

=== If every transaction is broadcast via the network, does BitCoin scale? ===
The Bitcoin protocol allows lightweight clients that can use Bitcoin without downloading the entire transaction history. As traffic grows and this becomes more critical, implementations of the concept will be developed. Full network nodes will at some point become a more specialized service.

With some modifications to the software, full BitCoin nodes could easily keep up with both VISA and MasterCard combined, using only fairly modest hardware (a couple of racks of machines using todays hardware). It's worth noting that the MasterCard network is structured somewhat like BitCoin itself - as a peer to peer broadcast network.

Learn more about [[Scalability]].

=== Why do I have to wait 10 minutes before I can spend money I received? ===

10 minutes is the average time taken to find a block. It can be significantly more or less time than that depending on luck; 10 minutes is simply the average case.

Blocks (shown as "confirmations" in the GUI) are how the BitCoin achieves consensus on who owns what. Once a block is found everyone agrees that you now own those coins, so you can spend them again. Until then it's possible that some network nodes believe otherwise, if somebody is attempting to defraud the system by reversing a transaction. The more confirmations a transaction has, the less risk there is of a reversal. Only 6 blocks or 1 hour is enough to make reversal computationally impractical. This is dramatically better than credit cards which can see chargebacks occur up to three months after the original transaction!

Why ten minutes specifically? It is a tradeoff chosen by Satoshi between propagation time of new blocks in large networks and the amount of work wasted due to chain splits. If that made no sense to you, don't worry. Reading [http://www.bitcoin.org/bitcoin.pdf the technical paper] should make things clearer.

=== Do you have to wait 10 minutes in order to buy or sell things with BitCoin? ===

No, it's reasonable to sell things without waiting for a confirmation as long as the transaction is not of high value.

When people ask this question they are usually thinking about applications like supermarkets or snack machines, as discussed in [http://www.bitcoin.org/smf/index.php?topic=423.msg3819#msg3819 this thread from July 2010]. Zero confirmation transactions still show up in the GUI, but you cannot spend them. You can however reason about the risk involved in assuming you ''will'' be able to spend them in future. In general, selling things that are fairly cheap (like snacks, digital downloads etc) for zero confirmations will not pose a problem if you are running a well connected node.

=== Why does my Bitcoin address keep changing? ===

Whenever the address listed in "Your address" receives a transaction, Bitcoin replaces it with a new address. This is meant to encourage you to use a new address for every transaction, which enhances [[anonymity]]. All of your old addresses are still usable: you can see them in ''Settings -> Your Receiving Addresses''.

==Economy==
=== Where does the value of Bitcoin stem from? What backs up Bitcoin? ===
Bitcoins have value because they are accepted as payment by many. See the [[Trade|list of Bitcoin-accepting sites]].

When we say that a currency is backed up by gold, we mean that there's a promise in place that you can exchange the currency for gold. In a sense, you could say that Bitcoin is "backed up" by the price tags of merchants – a price tag is a promise to exchange goods for a specified amount of currency.

It's a common misconception that Bitcoins gain their value from the cost of electricity required to generate them. Cost doesn't equal value – hiring 1,000 men to shovel a big hole in the ground may be costly, but not valuable. Also, even though scarcity is a critical requirement for a useful currency, it alone doesn't make anything valuable. For example, your fingerprints are scarce, but that doesn't mean they have any exchange value.

=== What if someone bought up all the existing Bitcoins? ===
What if somebody bought up all the gold in the world? Well, by attempting to buy it all, the buyer would just drive the prices up until he runs out of money.

Not all Bitcoins are for sale. Just as with gold, no one can buy a Bitcoin that isn't available for sale.

=== Bitcoin's monetary policy causes a deflationary spiral ===
See the article [[Deflationary spiral]].

=== Doesn't Bitcoin unfairly benefit early adopters? ===
Early adopters have a large number of bitcoins now because they took a risk and invested resources in an unproven technology. By so doing, they have helped Bitcoin become what it is now and what it will be in the future (hopefully, a ubiquitous decentralized digital currency). It is only fair they will reap the benefits of their successful investment.

In any case, any bitcoin generated will probably change hands dozens of time as a medium of exchange, so the profit made from the initial distribution will be insignificant compared to the total commerce enabled by Bitcoin.

=== Is Bitcoin a Ponzi scheme? ===
In a Ponzi Scheme, the founders persuade investors that they’ll profit. Bitcoin does not make such a guarantee. There is no central entity, just individuals building an economy.

A ponzi scheme is a zero sum game. Early adopters can only profit at the expense of late adopters. Bitcoin has possible win-win outcomes. Early adopters profit from the rise in value. Late adopters profit from the usefulness of a stable and widely accepted p2p currency.

The fact that early adopters benefit more doesn't alone make anything a ponzi scheme. Apple stocks aren't ponzi even though the early investors got rich.

=== Is Bitcoin a bubble? ===
Yes, in the same way as the euro and dollar are. They only have value in exchange and no value in use. If everyone suddenly stopped accepting your dollars, euros or bitcoins, the "bubble" would burst and their value would drop to zero. But that is unlikely to happen: even in Somalia, where the government collapsed 20 years ago, [http://en.wikipedia.org/wiki/Somali_shilling Somali shillings] are still accepted as payment.

==Networking==
=== Do I need to configure my firewall to run bitcoin? ===

Bitcoin will connect to other nodes, usually on tcp port 8333. You will need to allow outgoing TCP connections to port 8333 if you want to allow your bitcoin client to connect to many nodes. Bitcoin will also try to connect to IRC (tcp port 6667) to meet other nodes to connect to.

If you want to restrict your firewall rules to a few ips and/or don't want to allow IRC connection, you can find stable nodes in the [[Fallback Nodes|fallback nodes list]]. If your provider blocks the common IRC ports, note that lfnet also listens on port 7777. Connecting to this alternate port currently requires either recompiling Bitcoin, or changing routing rules. For example, on Linux you can evade a port 6667 block by doing something like this:

echo 173.246.103.92 irc.lfnet.org >> /etc/hosts
iptables -t nat -A OUTPUT -p tcp --dest 173.246.103.92 --dport 6667 -j DNAT --to-destination :7777 -m comment --comment "bitcoind irc connection"

=== How does the peer finding mechanism work? ===
Bitcoin finds peers primarily by connecting to an IRC server (channel #bitcoin on irc.lfnet.org). If a connection to the IRC server cannot be established (like when connecting through TOR), an in-built node list will be used and the nodes will be queried for more node addresses.

==Mining==
===What is mining?===
Mining is the process of spending computation power to find valid blocks and thus create new Bitcoins.

Technically speaking, mining is the calculation of a [[hash]] of the a block header, which includes among other things a reference to the previous block, a hash of a set of transactions and a [[nonce]]. If the hash value is found to be less than the current [[target]] (which is inversely proportional to the [[difficulty]]), a new block is formed and the miner gets 50 newly generated Bitcoins. If the hash is not less than the current target, a new nonce is tried, and a new hash is calculated. This is done millions of times per second by each miner.

===Why was the "Generate coin" option of the client software removed?===

In the early days of Bitcoin, it was easy for anyone to find new blocks using standard CPUs. As more and more people started mining, the [[difficulty]] of finding new blocks has greatly increased to the point where the average time for a CPU to find a single block can be many years. The only cost-effective method of mining is using a high-end graphics card with special software (see also [[Why a GPU mines faster than a CPU]]) and/or joining a [[Bitcoin Pool|mining pool]]. Since solo CPU mining is essentially useless, it was removed from the GUI of the Bitcoin software.

===Is mining used for some useful computation?===
The computations done when mining are internal to Bitcoin and not related to any other distributed computing projects. They serve the purpose of securing the Bitcoin network, which is useful.

===Is it not a waste of energy?===
Spending energy on creating a free monetary system is hardly a waste. Also, services necessary for the operation of currently widespread monetary systems, such as banks and credit card companies, also spend energy, arguably more than Bitcoin would.

===Why don't we use calculations that are also useful for some other purpose?===
To provide security for the Bitcoin network, the calculations involved need to have some very specific features. These features are incompatible with leveraging the computation for other purposes.

===How does the proof-of-work system help secure Bitcoin?===
To give a general idea of the mining process, imagine this setup:

payload = <some data related to things happening on the Bitcoin network>
nonce = 1
hash = [http://en.wikipedia.org/wiki/SHA2 SHA2]( [http://en.wikipedia.org/wiki/SHA2 SHA2]( payload + nonce ) )

The work performed by a miner consists of repeatedly increasing "nonce" until
the hash function yields a value, that has the rare property of being below a certain
target threshold. (In other words: The hash "starts with a certain number of zeroes",
if you display it in the fixed-length representation, that is typically used.)

As can be seen, the mining process doesn't compute anything special. It merely
tries to find a number (also referred to as nonce) which - in combination with the payload -
results in a hash with special properties.

The advantage of using such a mechanism consists of the fact, that it is very easy to check a result: Given
the payload and a specific nonce, only a single call of the hashing function
is needed to verify that the hash has the required properties. Since there is no
known way to find these hashes other than brute force, this can be used as a "proof of work"
that someone invested a lot of computing power to find the correct nonce for this payload.

This feature is then used in the Bitcoin network to secure various aspects. An attacker
that wants to introduce malicious payload data into the network, will need to do the
required proof of work before it will be accepted. And as long as honest miners have more
computing power, they can always outpace an attacker.

Also see [http://en.wikipedia.org/wiki/SHA2 SHA2] and [http://en.wikipedia.org/wiki/Proof-of-work_system Proof-of-work system] on Wikipedia.

==Help==
===I'd like to learn more. Where can I get help?===

* Read the [[Introduction|introduction to bitcoin]]
* See the videos, podcasts, and blog posts from the [[Press]]
* Read and post on the [[Bitcoin:Community_portal#Bitcoin_Community_Forums|forums]]
* Chat on one of the [[Bitcoin:Community_portal#IRC_Chat|Bitcoin IRC]] channels
* Listen to [http://omegataupodcast.net/2011/03/59-bitcoin-a-digital-decentralized-currency/ this podcast], which goes into the details of how bitcoin works

==See Also==

* [[Man page]]
* [[Introduction]]

[[de:FAQ]]
[[zh-cn:FAQ]]
[[fr:FAQ]]

[[Category:Technical]]
[[Category:Vocabulary]]

Help:FAQ

2011-06-19T15:25:35Z

Holy-Fire: /* Mining */ Move PoW to its own question

Here you will find answers to the most commonly asked questions.

== General ==
=== What are bitcoins? ===
Bitcoins are the unit of currency of the Bitcoin system. A commonly used shorthand for this is “BTC” to refer to a price or amount (eg: “100 BTC”).
A Bitcoin isn't tangible. It is just a number associated with a [[Address|Bitcoin Address]]. See also an [[Introduction|easy intro]] to bitcoin.

=== How can I get Bitcoins? ===

There are five ways to get Bitcoins:

* Buy them on an exchange such as [https://www.mtgox.com/ Mt. Gox] or [http://www.bitcoin-otc.com/ #bitcoin-otc] on FreeNode.
* Accept Bitcoins as payment for goods or services.
* Find a local trader on [http://tradebitcoin.com tradebitcoin] (or somewhere else) and trade with him in cash.
* Create a new [[block]] (currently yields 50 Bitcoins).
* Participate in a [[Pooled mining|mining pool]].

=== Can I buy Bitcoins with Paypal? ===

While it's possible to find an individual who wishes to sell Bitcoin to you via Paypal, (perhaps via [http://www.bitcoin-otc.com/ #bitcoin-otc] ) most major exchanges do not allow funding through Paypal. This is due to repeated cases where someone pays for Bitcoins with Paypal, receives their Bitcoins, and then fraudulently complains to Paypal that they never received their goods. Paypal too often sides with the fraudulent buyer in this case, and so exchangers no longer allow this method of funding.

Buying Bitcoins from individuals with this method is still possible, but requires mutual trust. In this case, Bitcoin seller beware.

=== How are new Bitcoins created? ===

[[File:total_bitcoins_over_time_graph.png|thumb|Number of bitcoins over time, assuming a perfect 10-minute interval.]]
New coins are generated by a network node each time it finds the solution to a certain mathematical problem (i.e. creates a new [[block]]), which is difficult to perform and can demonstrate a [[proof of work]]. The reward for solving a block is [[controlled inflation|automatically adjusted]] so that in the first 4 years of the Bitcoin network, 10,500,000 BTC will be created. The amount is halved each 4 years, so it will be 5,250,000 over years 4-8, 2,625,000 over years 8-12 and so on. Thus the total number of coins will approach 21,000,000 BTC over time.

In addition, built into the network is a system that attempts to allocate new coins in blocks about every 10 minutes, on average, somewhere on the network. As the number of people who attempt to generate these new coins changes, the difficulty of creating new coins changes. This happens in a manner that is agreed upon by the network as a whole, based upon the time taken to generate the previous 2016 blocks. The difficulty is therefore related to the average computing resources devoted to generate these new coins over the time it took to create these previous blocks. The likelihood of somebody "discovering" one of these blocks is based on the computer they are using compared to all of the computers also generating blocks on the network.

=== What's the current total number of Bitcoins in existence? ===

[http://blockexplorer.com/q/totalbc Current count]

The number of blocks times the coin value of a block is the number of coins in existence. The coin value of a block is 50 BTC for each of the first 210,000 blocks, 25 BTC for the next 210,000 blocks, then 12.5 BTC, 6.25 BTC and so on.

=== How divisible are Bitcoins? ===

Technically, a Bitcoin can be divided down to 8 decimals using existing data structures, so 0.00000001 BTC is the smallest amount currently possible. Discussions about and ideas for ways to provide for even smaller quantities of Bitcoins may be created in the future if the need for them ever arises.

=== What do I call the various denominations of Bitcoins? ===

There is a lot of discussion about the naming of these fractions of Bitcoins. The leading candidates are:

* 1 BTC = 1 Bitcoin
* 0.01 BTC = 1 cBTC = 1 Centi-Bitcoin (also referred to as Bitcent)
* 0.001 BTC = 1 mBTC = 1 Milli-Bitcoin (also referred to as mbit (pronounced em-bit) or millibit)
* 0.000 001 BTC = 1 μBTC = 1 Micro-Bitcoin (also referred to as ubit (pronounced yu-bit) or microbit)

The above follows the accepted international SI units for thousandths, millionths and billionths. There are many arguments against the special case of 0.01 BTC since it is unlikely to represent anything meaningful as the Bitcoin economy grows (it certainly won't be the equivalent of 0.01 USD, GBP or EUR). Equally, the inclusion of existing national currency denominations such as "cent", "nickel", "dime", "pence", "pound", "kopek" and so on are to be discouraged. This is a worldwide currency.

One exception is the "satoshi" which is smallest denomination currently possible

* 0.000 000 01 BTC = 1 Satoshi (pronounced sa-toh-shee)

which is so named in honour of Satoshi Nakamoto the pseudonym of the inventor of Bitcoin.

For an overview of all defined units of Bitcoin (including less common and niche units), see [[Units]].

Further discussion on this topic can be found on the forums here:

* [http://forum.bitcoin.org/index.php?topic=14438.msg195287#msg195287 We need names]
* [http://forum.bitcoin.org/index.php?topic=8282.0 What to call 0.001 BTC]

=== How does the halving work when the number gets really small? ===

The reward will go from 0.00000001 BTC to 0. Then no more coins will likely be created.

The calculation is done as a right bitwise shift of a 64-bit signed integer, which means it is divided by 2 and rounded down. The integer is equal to the value in BTC * 100,000,000. This is how all Bitcoin balances/values are stored internally.

Keep in mind that using current rules this will take nearly 100 years before it becomes an issue and Bitcoins may change considerably before that happens.

=== How long will it take to generate all the coins? ===

The last block that will generate coins will be block #6,929,999. This should be generated around year 2140. Then the total number of coins in circulation will remain static at 20,999,999.9769 BTC.

Even if the allowed precision is expanded from the current 8 decimals, the total BTC in circulation will always be slightly below 21 million (assuming everything else stays the same). For example, with 16 decimals of precision, the end total would be 20999999.999999999496 BTC.

=== If no more coins are going to be generated, will more blocks be created? ===

Absolutely! Even before the creation of coins ends, the use of [[transaction fee|transaction fees]] will likely make creating new blocks more valuable from the fees than the new coins being created. When coin generation ends, what will sustain the ability to use bitcoins will be these fees entirely. There will be blocks generated after block #6,929,999, assuming that people are still using Bitcoins at that time.

=== But if no more coins are generated, what happens when Bitcoins are lost? Won't that be a problem? ===

Not at all. Because of the law of supply and demand, when fewer Bitcoins are available the ones that are left will be in higher demand, and therefore will have a higher value. So when Bitcoins are lost, the remaining Bitcoins will increase in value to compensate. As the value of Bitcoins increase, the number of Bitcoins required to purchase an item '''de'''creases. This is known as a [[Deflationary spiral|deflationary economic model]]. Eventually, if and when it gets to the point where the largest transaction is less than 1BTC, then it's a simple matter of shifting the decimal place to the right a few places, and the system continues.

=== If every transaction is broadcast via the network, does BitCoin scale? ===
The Bitcoin protocol allows lightweight clients that can use Bitcoin without downloading the entire transaction history. As traffic grows and this becomes more critical, implementations of the concept will be developed. Full network nodes will at some point become a more specialized service.

With some modifications to the software, full BitCoin nodes could easily keep up with both VISA and MasterCard combined, using only fairly modest hardware (a couple of racks of machines using todays hardware). It's worth noting that the MasterCard network is structured somewhat like BitCoin itself - as a peer to peer broadcast network.

Learn more about [[Scalability]].

=== Why do I have to wait 10 minutes before I can spend money I received? ===

10 minutes is the average time taken to find a block. It can be significantly more or less time than that depending on luck; 10 minutes is simply the average case.

Blocks (shown as "confirmations" in the GUI) are how the BitCoin achieves consensus on who owns what. Once a block is found everyone agrees that you now own those coins, so you can spend them again. Until then it's possible that some network nodes believe otherwise, if somebody is attempting to defraud the system by reversing a transaction. The more confirmations a transaction has, the less risk there is of a reversal. Only 6 blocks or 1 hour is enough to make reversal computationally impractical. This is dramatically better than credit cards which can see chargebacks occur up to three months after the original transaction!

Why ten minutes specifically? It is a tradeoff chosen by Satoshi between propagation time of new blocks in large networks and the amount of work wasted due to chain splits. If that made no sense to you, don't worry. Reading [http://www.bitcoin.org/bitcoin.pdf the technical paper] should make things clearer.

=== Do you have to wait 10 minutes in order to buy or sell things with BitCoin? ===

No, it's reasonable to sell things without waiting for a confirmation as long as the transaction is not of high value.

When people ask this question they are usually thinking about applications like supermarkets or snack machines, as discussed in [http://www.bitcoin.org/smf/index.php?topic=423.msg3819#msg3819 this thread from July 2010]. Zero confirmation transactions still show up in the GUI, but you cannot spend them. You can however reason about the risk involved in assuming you ''will'' be able to spend them in future. In general, selling things that are fairly cheap (like snacks, digital downloads etc) for zero confirmations will not pose a problem if you are running a well connected node.

=== Why does my Bitcoin address keep changing? ===

Whenever the address listed in "Your address" receives a transaction, Bitcoin replaces it with a new address. This is meant to encourage you to use a new address for every transaction, which enhances [[anonymity]]. All of your old addresses are still usable: you can see them in ''Settings -> Your Receiving Addresses''.

==Economy==
=== Where does the value of Bitcoin stem from? What backs up Bitcoin? ===
Bitcoins have value because they are accepted as payment by many. See the [[Trade|list of Bitcoin-accepting sites]].

When we say that a currency is backed up by gold, we mean that there's a promise in place that you can exchange the currency for gold. In a sense, you could say that Bitcoin is "backed up" by the price tags of merchants – a price tag is a promise to exchange goods for a specified amount of currency.

It's a common misconception that Bitcoins gain their value from the cost of electricity required to generate them. Cost doesn't equal value – hiring 1,000 men to shovel a big hole in the ground may be costly, but not valuable. Also, even though scarcity is a critical requirement for a useful currency, it alone doesn't make anything valuable. For example, your fingerprints are scarce, but that doesn't mean they have any exchange value.

=== What if someone bought up all the existing Bitcoins? ===
What if somebody bought up all the gold in the world? Well, by attempting to buy it all, the buyer would just drive the prices up until he runs out of money.

Not all Bitcoins are for sale. Just as with gold, no one can buy a Bitcoin that isn't available for sale.

=== Bitcoin's monetary policy causes a deflationary spiral ===
See the article [[Deflationary spiral]].

=== Doesn't Bitcoin unfairly benefit early adopters? ===
Early adopters have a large number of bitcoins now because they took a risk and invested resources in an unproven technology. By so doing, they have helped Bitcoin become what it is now and what it will be in the future (hopefully, a ubiquitous decentralized digital currency). It is only fair they will reap the benefits of their successful investment.

In any case, any bitcoin generated will probably change hands dozens of time as a medium of exchange, so the profit made from the initial distribution will be insignificant compared to the total commerce enabled by Bitcoin.

=== Is Bitcoin a Ponzi scheme? ===
In a Ponzi Scheme, the founders persuade investors that they’ll profit. Bitcoin does not make such a guarantee. There is no central entity, just individuals building an economy.

A ponzi scheme is a zero sum game. Early adopters can only profit at the expense of late adopters. Bitcoin has possible win-win outcomes. Early adopters profit from the rise in value. Late adopters profit from the usefulness of a stable and widely accepted p2p currency.

The fact that early adopters benefit more doesn't alone make anything a ponzi scheme. Apple stocks aren't ponzi even though the early investors got rich.

=== Is Bitcoin a bubble? ===
Yes, in the same way as the euro and dollar are. They only have value in exchange and no value in use. If everyone suddenly stopped accepting your dollars, euros or bitcoins, the "bubble" would burst and their value would drop to zero. But that is unlikely to happen: even in Somalia, where the government collapsed 20 years ago, [http://en.wikipedia.org/wiki/Somali_shilling Somali shillings] are still accepted as payment.

==Networking==
=== Do I need to configure my firewall to run bitcoin? ===

Bitcoin will connect to other nodes, usually on tcp port 8333. You will need to allow outgoing TCP connections to port 8333 if you want to allow your bitcoin client to connect to many nodes. Bitcoin will also try to connect to IRC (tcp port 6667) to meet other nodes to connect to.

If you want to restrict your firewall rules to a few ips and/or don't want to allow IRC connection, you can find stable nodes in the [[Fallback Nodes|fallback nodes list]]. If your provider blocks the common IRC ports, note that lfnet also listens on port 7777. Connecting to this alternate port currently requires either recompiling Bitcoin, or changing routing rules. For example, on Linux you can evade a port 6667 block by doing something like this:

echo 173.246.103.92 irc.lfnet.org >> /etc/hosts
iptables -t nat -A OUTPUT -p tcp --dest 173.246.103.92 --dport 6667 -j DNAT --to-destination :7777 -m comment --comment "bitcoind irc connection"

=== How does the peer finding mechanism work? ===
Bitcoin finds peers primarily by connecting to an IRC server (channel #bitcoin on irc.lfnet.org). If a connection to the IRC server cannot be established (like when connecting through TOR), an in-built node list will be used and the nodes will be queried for more node addresses.

==Mining==
===What is mining?===
Mining is the process of spending computation power to find valid blocks and thus create new Bitcoins.

Technically speaking, mining is the calculation of a [[hash]] of the a block header, which includes among other things a reference to the previous block, a hash of a set of transactions and a [[nonce]]. If the hash value is found to be less than the current [[target]] (which is inversely proportional to the [[difficulty]]), a new block is formed and the miner gets 50 newly generated Bitcoins. If the hash is not less than the current target, a new nonce is tried, and a new hash is calculated. This is done millions of times per second by each miner.

===I've been mining for a long time and haven't created any new Bitcoins. What's wrong?===

In the early days of Bitcoin, it was easy for anyone to find new blocks using standard CPUs. As more and more people started mining, the [[difficulty]] of finding new blocks has greatly increased to the point where the average time for a CPU to find a single block can be many years. The only cost- or time-effective method of mining is using a high-end graphics card with special software (see also [[Why a GPU mines faster than a CPU]]). Since CPU mining is essentially useless, it may be removed from future versions of the Bitcoin software.

===Is mining used for some useful computation?===
The computations done when mining are internal to Bitcoin and not related to any other distributed computing projects. They serve the purpose of securing the Bitcoin network, which is useful.

===Is it not a waste of energy?===
Spending energy on creating a free monetary system is hardly a waste. Also, services necessary for the operation of currently widespread monetary systems, such as banks and credit card companies, also spend energy, arguably more than Bitcoin would.

===Why don't we use calculations that are also useful for some other purpose?===
To provide security for the Bitcoin network, the calculations involved need to have some very specific features. These features are incompatible with leveraging the computation for other purposes.

===How does the proof-of-work system help secure Bitcoin?===
To give a general idea of the mining process, imagine this setup:

payload = <some data related to things happening on the Bitcoin network>
nonce = 1
hash = [http://en.wikipedia.org/wiki/SHA2 SHA2]( [http://en.wikipedia.org/wiki/SHA2 SHA2]( payload + nonce ) )

The work performed by a miner consists of repeatedly increasing "nonce" until
the hash function yields a value, that has the rare property of being below a certain
target threshold. (In other words: The hash "starts with a certain number of zeroes",
if you display it in the fixed-length representation, that is typically used.)

As can be seen, the mining process doesn't compute anything special. It merely
tries to find a number (also referred to as nonce) which - in combination with the payload -
results in a hash with special properties.

The advantage of using such a mechanism consists of the fact, that it is very easy to check a result: Given
the payload and a specific nonce, only a single call of the hashing function
is needed to verify that the hash has the required properties. Since there is no
known way to find these hashes other than brute force, this can be used as a "proof of work"
that someone invested a lot of computing power to find the correct nonce for this payload.

This feature is then used in the Bitcoin network to secure various aspects. An attacker
that wants to introduce malicious payload data into the network, will need to do the
required proof of work before it will be accepted. And as long as honest miners have more
computing power, they can always outpace an attacker.

Also see [http://en.wikipedia.org/wiki/SHA2 SHA2] and [http://en.wikipedia.org/wiki/Proof-of-work_system Proof-of-work system] on Wikipedia.

==Help==
===I'd like to learn more. Where can I get help?===

* Read the [[Introduction|introduction to bitcoin]]
* See the videos, podcasts, and blog posts from the [[Press]]
* Read and post on the [[Bitcoin:Community_portal#Bitcoin_Community_Forums|forums]]
* Chat on one of the [[Bitcoin:Community_portal#IRC_Chat|Bitcoin IRC]] channels
* Listen to [http://omegataupodcast.net/2011/03/59-bitcoin-a-digital-decentralized-currency/ this podcast], which goes into the details of how bitcoin works

==See Also==

* [[Man page]]
* [[Introduction]]

[[de:FAQ]]
[[zh-cn:FAQ]]
[[fr:FAQ]]

[[Category:Technical]]
[[Category:Vocabulary]]

Help:FAQ

2011-06-19T15:22:26Z

Holy-Fire: /* What is mining? */

Here you will find answers to the most commonly asked questions.

== General ==
=== What are bitcoins? ===
Bitcoins are the unit of currency of the Bitcoin system. A commonly used shorthand for this is “BTC” to refer to a price or amount (eg: “100 BTC”).
A Bitcoin isn't tangible. It is just a number associated with a [[Address|Bitcoin Address]]. See also an [[Introduction|easy intro]] to bitcoin.

=== How can I get Bitcoins? ===

There are five ways to get Bitcoins:

* Buy them on an exchange such as [https://www.mtgox.com/ Mt. Gox] or [http://www.bitcoin-otc.com/ #bitcoin-otc] on FreeNode.
* Accept Bitcoins as payment for goods or services.
* Find a local trader on [http://tradebitcoin.com tradebitcoin] (or somewhere else) and trade with him in cash.
* Create a new [[block]] (currently yields 50 Bitcoins).
* Participate in a [[Pooled mining|mining pool]].

=== Can I buy Bitcoins with Paypal? ===

While it's possible to find an individual who wishes to sell Bitcoin to you via Paypal, (perhaps via [http://www.bitcoin-otc.com/ #bitcoin-otc] ) most major exchanges do not allow funding through Paypal. This is due to repeated cases where someone pays for Bitcoins with Paypal, receives their Bitcoins, and then fraudulently complains to Paypal that they never received their goods. Paypal too often sides with the fraudulent buyer in this case, and so exchangers no longer allow this method of funding.

Buying Bitcoins from individuals with this method is still possible, but requires mutual trust. In this case, Bitcoin seller beware.

=== How are new Bitcoins created? ===

[[File:total_bitcoins_over_time_graph.png|thumb|Number of bitcoins over time, assuming a perfect 10-minute interval.]]
New coins are generated by a network node each time it finds the solution to a certain mathematical problem (i.e. creates a new [[block]]), which is difficult to perform and can demonstrate a [[proof of work]]. The reward for solving a block is [[controlled inflation|automatically adjusted]] so that in the first 4 years of the Bitcoin network, 10,500,000 BTC will be created. The amount is halved each 4 years, so it will be 5,250,000 over years 4-8, 2,625,000 over years 8-12 and so on. Thus the total number of coins will approach 21,000,000 BTC over time.

In addition, built into the network is a system that attempts to allocate new coins in blocks about every 10 minutes, on average, somewhere on the network. As the number of people who attempt to generate these new coins changes, the difficulty of creating new coins changes. This happens in a manner that is agreed upon by the network as a whole, based upon the time taken to generate the previous 2016 blocks. The difficulty is therefore related to the average computing resources devoted to generate these new coins over the time it took to create these previous blocks. The likelihood of somebody "discovering" one of these blocks is based on the computer they are using compared to all of the computers also generating blocks on the network.

=== What's the current total number of Bitcoins in existence? ===

[http://blockexplorer.com/q/totalbc Current count]

The number of blocks times the coin value of a block is the number of coins in existence. The coin value of a block is 50 BTC for each of the first 210,000 blocks, 25 BTC for the next 210,000 blocks, then 12.5 BTC, 6.25 BTC and so on.

=== How divisible are Bitcoins? ===

Technically, a Bitcoin can be divided down to 8 decimals using existing data structures, so 0.00000001 BTC is the smallest amount currently possible. Discussions about and ideas for ways to provide for even smaller quantities of Bitcoins may be created in the future if the need for them ever arises.

=== What do I call the various denominations of Bitcoins? ===

There is a lot of discussion about the naming of these fractions of Bitcoins. The leading candidates are:

* 1 BTC = 1 Bitcoin
* 0.01 BTC = 1 cBTC = 1 Centi-Bitcoin (also referred to as Bitcent)
* 0.001 BTC = 1 mBTC = 1 Milli-Bitcoin (also referred to as mbit (pronounced em-bit) or millibit)
* 0.000 001 BTC = 1 μBTC = 1 Micro-Bitcoin (also referred to as ubit (pronounced yu-bit) or microbit)

The above follows the accepted international SI units for thousandths, millionths and billionths. There are many arguments against the special case of 0.01 BTC since it is unlikely to represent anything meaningful as the Bitcoin economy grows (it certainly won't be the equivalent of 0.01 USD, GBP or EUR). Equally, the inclusion of existing national currency denominations such as "cent", "nickel", "dime", "pence", "pound", "kopek" and so on are to be discouraged. This is a worldwide currency.

One exception is the "satoshi" which is smallest denomination currently possible

* 0.000 000 01 BTC = 1 Satoshi (pronounced sa-toh-shee)

which is so named in honour of Satoshi Nakamoto the pseudonym of the inventor of Bitcoin.

For an overview of all defined units of Bitcoin (including less common and niche units), see [[Units]].

Further discussion on this topic can be found on the forums here:

* [http://forum.bitcoin.org/index.php?topic=14438.msg195287#msg195287 We need names]
* [http://forum.bitcoin.org/index.php?topic=8282.0 What to call 0.001 BTC]

=== How does the halving work when the number gets really small? ===

The reward will go from 0.00000001 BTC to 0. Then no more coins will likely be created.

The calculation is done as a right bitwise shift of a 64-bit signed integer, which means it is divided by 2 and rounded down. The integer is equal to the value in BTC * 100,000,000. This is how all Bitcoin balances/values are stored internally.

Keep in mind that using current rules this will take nearly 100 years before it becomes an issue and Bitcoins may change considerably before that happens.

=== How long will it take to generate all the coins? ===

The last block that will generate coins will be block #6,929,999. This should be generated around year 2140. Then the total number of coins in circulation will remain static at 20,999,999.9769 BTC.

Even if the allowed precision is expanded from the current 8 decimals, the total BTC in circulation will always be slightly below 21 million (assuming everything else stays the same). For example, with 16 decimals of precision, the end total would be 20999999.999999999496 BTC.

=== If no more coins are going to be generated, will more blocks be created? ===

Absolutely! Even before the creation of coins ends, the use of [[transaction fee|transaction fees]] will likely make creating new blocks more valuable from the fees than the new coins being created. When coin generation ends, what will sustain the ability to use bitcoins will be these fees entirely. There will be blocks generated after block #6,929,999, assuming that people are still using Bitcoins at that time.

=== But if no more coins are generated, what happens when Bitcoins are lost? Won't that be a problem? ===

Not at all. Because of the law of supply and demand, when fewer Bitcoins are available the ones that are left will be in higher demand, and therefore will have a higher value. So when Bitcoins are lost, the remaining Bitcoins will increase in value to compensate. As the value of Bitcoins increase, the number of Bitcoins required to purchase an item '''de'''creases. This is known as a [[Deflationary spiral|deflationary economic model]]. Eventually, if and when it gets to the point where the largest transaction is less than 1BTC, then it's a simple matter of shifting the decimal place to the right a few places, and the system continues.

=== If every transaction is broadcast via the network, does BitCoin scale? ===
The Bitcoin protocol allows lightweight clients that can use Bitcoin without downloading the entire transaction history. As traffic grows and this becomes more critical, implementations of the concept will be developed. Full network nodes will at some point become a more specialized service.

With some modifications to the software, full BitCoin nodes could easily keep up with both VISA and MasterCard combined, using only fairly modest hardware (a couple of racks of machines using todays hardware). It's worth noting that the MasterCard network is structured somewhat like BitCoin itself - as a peer to peer broadcast network.

Learn more about [[Scalability]].

=== Why do I have to wait 10 minutes before I can spend money I received? ===

10 minutes is the average time taken to find a block. It can be significantly more or less time than that depending on luck; 10 minutes is simply the average case.

Blocks (shown as "confirmations" in the GUI) are how the BitCoin achieves consensus on who owns what. Once a block is found everyone agrees that you now own those coins, so you can spend them again. Until then it's possible that some network nodes believe otherwise, if somebody is attempting to defraud the system by reversing a transaction. The more confirmations a transaction has, the less risk there is of a reversal. Only 6 blocks or 1 hour is enough to make reversal computationally impractical. This is dramatically better than credit cards which can see chargebacks occur up to three months after the original transaction!

Why ten minutes specifically? It is a tradeoff chosen by Satoshi between propagation time of new blocks in large networks and the amount of work wasted due to chain splits. If that made no sense to you, don't worry. Reading [http://www.bitcoin.org/bitcoin.pdf the technical paper] should make things clearer.

=== Do you have to wait 10 minutes in order to buy or sell things with BitCoin? ===

No, it's reasonable to sell things without waiting for a confirmation as long as the transaction is not of high value.

When people ask this question they are usually thinking about applications like supermarkets or snack machines, as discussed in [http://www.bitcoin.org/smf/index.php?topic=423.msg3819#msg3819 this thread from July 2010]. Zero confirmation transactions still show up in the GUI, but you cannot spend them. You can however reason about the risk involved in assuming you ''will'' be able to spend them in future. In general, selling things that are fairly cheap (like snacks, digital downloads etc) for zero confirmations will not pose a problem if you are running a well connected node.

=== Why does my Bitcoin address keep changing? ===

Whenever the address listed in "Your address" receives a transaction, Bitcoin replaces it with a new address. This is meant to encourage you to use a new address for every transaction, which enhances [[anonymity]]. All of your old addresses are still usable: you can see them in ''Settings -> Your Receiving Addresses''.

==Economy==
=== Where does the value of Bitcoin stem from? What backs up Bitcoin? ===
Bitcoins have value because they are accepted as payment by many. See the [[Trade|list of Bitcoin-accepting sites]].

When we say that a currency is backed up by gold, we mean that there's a promise in place that you can exchange the currency for gold. In a sense, you could say that Bitcoin is "backed up" by the price tags of merchants – a price tag is a promise to exchange goods for a specified amount of currency.

It's a common misconception that Bitcoins gain their value from the cost of electricity required to generate them. Cost doesn't equal value – hiring 1,000 men to shovel a big hole in the ground may be costly, but not valuable. Also, even though scarcity is a critical requirement for a useful currency, it alone doesn't make anything valuable. For example, your fingerprints are scarce, but that doesn't mean they have any exchange value.

=== What if someone bought up all the existing Bitcoins? ===
What if somebody bought up all the gold in the world? Well, by attempting to buy it all, the buyer would just drive the prices up until he runs out of money.

Not all Bitcoins are for sale. Just as with gold, no one can buy a Bitcoin that isn't available for sale.

=== Bitcoin's monetary policy causes a deflationary spiral ===
See the article [[Deflationary spiral]].

=== Doesn't Bitcoin unfairly benefit early adopters? ===
Early adopters have a large number of bitcoins now because they took a risk and invested resources in an unproven technology. By so doing, they have helped Bitcoin become what it is now and what it will be in the future (hopefully, a ubiquitous decentralized digital currency). It is only fair they will reap the benefits of their successful investment.

In any case, any bitcoin generated will probably change hands dozens of time as a medium of exchange, so the profit made from the initial distribution will be insignificant compared to the total commerce enabled by Bitcoin.

=== Is Bitcoin a Ponzi scheme? ===
In a Ponzi Scheme, the founders persuade investors that they’ll profit. Bitcoin does not make such a guarantee. There is no central entity, just individuals building an economy.

A ponzi scheme is a zero sum game. Early adopters can only profit at the expense of late adopters. Bitcoin has possible win-win outcomes. Early adopters profit from the rise in value. Late adopters profit from the usefulness of a stable and widely accepted p2p currency.

The fact that early adopters benefit more doesn't alone make anything a ponzi scheme. Apple stocks aren't ponzi even though the early investors got rich.

=== Is Bitcoin a bubble? ===
Yes, in the same way as the euro and dollar are. They only have value in exchange and no value in use. If everyone suddenly stopped accepting your dollars, euros or bitcoins, the "bubble" would burst and their value would drop to zero. But that is unlikely to happen: even in Somalia, where the government collapsed 20 years ago, [http://en.wikipedia.org/wiki/Somali_shilling Somali shillings] are still accepted as payment.

==Networking==
=== Do I need to configure my firewall to run bitcoin? ===

Bitcoin will connect to other nodes, usually on tcp port 8333. You will need to allow outgoing TCP connections to port 8333 if you want to allow your bitcoin client to connect to many nodes. Bitcoin will also try to connect to IRC (tcp port 6667) to meet other nodes to connect to.

If you want to restrict your firewall rules to a few ips and/or don't want to allow IRC connection, you can find stable nodes in the [[Fallback Nodes|fallback nodes list]]. If your provider blocks the common IRC ports, note that lfnet also listens on port 7777. Connecting to this alternate port currently requires either recompiling Bitcoin, or changing routing rules. For example, on Linux you can evade a port 6667 block by doing something like this:

echo 173.246.103.92 irc.lfnet.org >> /etc/hosts
iptables -t nat -A OUTPUT -p tcp --dest 173.246.103.92 --dport 6667 -j DNAT --to-destination :7777 -m comment --comment "bitcoind irc connection"

=== How does the peer finding mechanism work? ===
Bitcoin finds peers primarily by connecting to an IRC server (channel #bitcoin on irc.lfnet.org). If a connection to the IRC server cannot be established (like when connecting through TOR), an in-built node list will be used and the nodes will be queried for more node addresses.

==Mining==
===What is mining?===
Mining is the process of spending computation power to find valid blocks and thus create new Bitcoins.

Technically speaking, mining is the calculation of a [[hash]] of the a block header, which includes among other things a reference to the previous block, a hash of a set of transactions and a [[nonce]]. If the hash value is found to be less than the current [[target]] (which is inversely proportional to the [[difficulty]]), a new block is formed and the miner gets 50 newly generated Bitcoins. If the hash is not less than the current target, a new nonce is tried, and a new hash is calculated. This is done millions of times per second by each miner.

===I've been mining for a long time and haven't created any new Bitcoins. What's wrong?===

In the early days of Bitcoin, it was easy for anyone to find new blocks using standard CPUs. As more and more people started mining, the [[difficulty]] of finding new blocks has greatly increased to the point where the average time for a CPU to find a single block can be many years. The only cost- or time-effective method of mining is using a high-end graphics card with special software (see also [[Why a GPU mines faster than a CPU]]). Since CPU mining is essentially useless, it may be removed from future versions of the Bitcoin software.

===Is mining used for some useful computation?===
The computations done when mining are internal to Bitcoin and not related to any other distributed computing projects. They serve the purpose of securing the Bitcoin network, which is useful.

To give a general idea of the mining process, imagine this setup:

payload = <some data related to things happening on the Bitcoin network>
nonce = 1
hash = [http://en.wikipedia.org/wiki/SHA2 SHA2]( [http://en.wikipedia.org/wiki/SHA2 SHA2]( payload + nonce ) )

The work performed by a miner consists of repeatedly increasing "nonce" until
the hash function yields a value, that has the rare property of being below a certain
target threshold. (In other words: The hash "starts with a certain number of zeroes",
if you display it in the fixed-length representation, that is typically used.)

As can be seen, the mining process doesn't compute anything special. It merely
tries to find a number (also referred to as nonce) which - in combination with the payload -
results in a hash with special properties.

The advantage of using such a mechanism consists of the fact, that it is very easy to check a result: Given
the payload and a specific nonce, only a single call of the hashing function
is needed to verify that the hash has the required properties. Since there is no
known way to find these hashes other than brute force, this can be used as a "proof of work"
that someone invested a lot of computing power to find the correct nonce for this payload.

This feature is then used in the Bitcoin network to secure various aspects. An attacker
that wants to introduce malicious payload data into the network, will need to do the
required proof of work before it will be accepted. And as long as honest miners have more
computing power, they can always outpace an attacker.

Also see [http://en.wikipedia.org/wiki/SHA2 SHA2] and [http://en.wikipedia.org/wiki/Proof-of-work_system Proof-of-work system] on Wikipedia.

===Is it not a waste of energy?===
Spending energy on creating a free monetary system is hardly a waste. Also, services necessary for the operation of currently widespread monetary systems, such as banks and credit card companies, also spend energy, arguably more than Bitcoin would.

===Why don't we use calculations that are also useful for some other purpose?===
To provide security for the Bitcoin network, the calculations involved need to have some very specific features. These features are incompatible with leveraging the computation for other purposes.

==Help==
===I'd like to learn more. Where can I get help?===

* Read the [[Introduction|introduction to bitcoin]]
* See the videos, podcasts, and blog posts from the [[Press]]
* Read and post on the [[Bitcoin:Community_portal#Bitcoin_Community_Forums|forums]]
* Chat on one of the [[Bitcoin:Community_portal#IRC_Chat|Bitcoin IRC]] channels
* Listen to [http://omegataupodcast.net/2011/03/59-bitcoin-a-digital-decentralized-currency/ this podcast], which goes into the details of how bitcoin works

==See Also==

* [[Man page]]
* [[Introduction]]

[[de:FAQ]]
[[zh-cn:FAQ]]
[[fr:FAQ]]

[[Category:Technical]]
[[Category:Vocabulary]]

Helping Bitcoin

2011-06-19T15:06:28Z

Holy-Fire: /* Be Creative */ If anything it's hack, not crack

{{Template:Stub}}

The question is: how does one 'help' Bitcoin if it is an online currency that is not managed by any one individual? Often, those who take an interest in Bitcoin are at a loss as to how they can provide their support for this community. This article aims to offer some direction.

==Join the ''Bitcoin Community''==

Find a community that you would naturally be a part of that accepts and supports Bitcoin, be it your workplace, schools, neighborhood, or online. The Bitcoin community is made up simply of the many supporters of the currency from all over the world. Spread the word—inform others wherever and whenever you can.

==Be Creative==

Everyone possesses their own unique talents and abilities; these qualities are what make us the people we are and bring us together. Utilize your skills and creativity to assist.

* '''Hack''' the Bitcoin source. This may prove useful to those familiar with coding.

* '''Mine'''. If you're into high-efficiency computing, creating a strong miner will definitely get you going.

* If you own a business, '''accept Bitcoin for your services'''. You may also wish to encourage other businesses to follow in your footsteps.

* '''Speculate''' in Bitcoin. This improves its liquidity and helps every other person using Bitcoin to carry out real transactions.

Every task and part that people take on adds stability and flexibility to the Bitcoin economy.

==Third: Be Wise==

Everyone has limited resources, and not all people think in the same way that you do. Trust no one, research, and expect the unexpected.

Talk:Mining pool reward FAQ

2011-05-28T19:57:18Z

Holy-Fire: /* Pool-hopping */

==Content dispute==

I think this revision by holy-fire is the best.
https://en.bitcoin.it/w/index.php?title=Mining_pool_reward_FAQ&oldid=8977

all it needs is a citation to the whitepaper describing the pool hopping attack
and also a citation to the closing of bitpenny, which is strongly suspected, on statistical grounds, by that pool's operator, of being due to griefing (real-block withholding).

Subject to further user comments, i plan to revert the page to this revision. --[[User:Nanotube|Nanotube]] 20:25, 26 May 2011 (GMT)

* That revision contains FUD about pool-hopping on share-based pools (it is not an attack, and is not cheating). The only time pool-hopping creates unfair rewards is when score-based pools are involved. It also discounts as a myth, the fact that share-based pools are disadvantageous to intermittent miners. --[[User:Luke-jr|Luke-jr]] 20:32, 26 May 2011 (GMT)

:: Regarding share-based pools. If I understand it correctly, they are not disadvantageous to intermittent miners. It is just as likely that the miner will mine during the last part of a round, finding more valuable shares, than they are to mine during the beginning, when they're worth less. Thus, a miner who only mines for half an hour a day may find newer shares one day and earn half a bitcoin, while on other he may find older shares, and only earn 1/10 Bitcoins. --[[User:Firestorm|<tt><big>'''Firestorm'''</big></tt>]] 13:34, 27 May 2011 (GMT)

==Pool-hopping==
I strongly object to having Pool-Hopping included in this article. It's a way of cheating the system. It's a system that increases how much you make at the expense of others who are earning it in a more fair way. If pool-hopping can directly cause a system to FAIL, it should NOT be advertised as a good way to earn more bitcoins --[[User:Firestorm|<tt><big>'''Firestorm'''</big></tt>]] 23:10, 26 May 2011 (GMT)
** It is just as much "at the expense of others" as is BFI_INT, GPUs, or any other improvement in efficiency. Pool-hopping cannot cause a system to fail, and is not being advertised as good. The language is intentionally neutral, while giving all the facts. --[[User:Luke-jr|Luke-jr]] 23:21, 26 May 2011 (GMT)
:: It directly states that pools can be brought to a standstill using this. Anything that results in pools blacklisting them is not something to be advertised. I feel that it would be like going onto a gaming Wiki and linking to all the hacks and exploits in the game --[[User:Firestorm|<tt><big>'''Firestorm'''</big></tt>]] 23:30, 26 May 2011 (GMT)
:First I'd like to clarify that Luke's points about "score-based could lead to reverse pool-hopping" and "score-based penalized intermittance" are both wrong (as I've also tries to explain [http://forum.bitcoin.org/index.php?topic=10038.msg145296#msg145296 here]). As for the first, my method was specifically calibrated to be immune to any round-age hopping, whether forward and reverse (and slush's method is somewhat subject to forward hopping, but not reverse). And disconnecting from a score-based pool has no effect on already submitted shares.
:Luke does bring up an interesting point. If there were only proportional pools, and solo would be impractical, and everybody would pool-hop, then it will reach the point that everyone mines for the youngest-round pool at each point, so it would even out while giving more power to the smaller pools. However:
:*Solo mining will exist, and will give a nice payout bonus over the hashrate ratio for those who can mine solo;
:*Score-based pools will exist, and they'll be the target once all proportional pools reach 43.5%, so proportional pools will eventually freeze and never receive a share again.
:*With BFI_INT, we need to adopt it for security reasons, because an attacker on the network ''will'' use it and gain an advantage on the honest network if we don't. With pool hopping, we don't need to adopt it because it can't be used by an attacker for an advantage.
:So I don't think this is really a sustainable solution. [[User:Holy-Fire|Holy-Fire]] 04:15, 27 May 2011 (GMT)
:And, if this wiki page is to remain, we need to sort this out and include all relevant information. It would be silly to even mention reward systems at all without specifying their advantages and disadvantages (and it would be silly to have a reward FAQ without explaining reward systems). [[User:Holy-Fire|Holy-Fire]] 04:17, 27 May 2011 (GMT)
** I admit the geometric method does seem to prevent pool hopping ''to an extent'', but also makes the pool operator vulnerable to a similar attack as the PPS model. While it is ''possible'' that an intermittent miner ''might'' even out on a score-based system, he is still penalized when he would join during the early stages of a block. If he know he'll only be able to mine for an hour, why would he join a pool knowing that he's unlikely to be rewarded for it? This is effectively inverse pool hopping. But would you say miners have an obligation to stick to a single pool, and never mine on others or solo-mine? That is, IMO, ridiculous without a clearly well-defined rule by the pool on ''when'' it is acceptable to hop/leave.
** With solo mining comes a greater risk than in a pool, so hopping to solo-mining is a fair risk/gain tradeoff.
** Your second point more or less admits that score-based pools in fact "attacking" share-based pools in practice.
** BFI_INT adoption is not needed any more or less than pool hopping on share-based pools.
** I agree that it isn't sustainable in the long-run, but it is a legitimate strategy, and within the rights of miners to practice. If pools don't like it (as they shouldn't), it is also reasonable for them to make a rule restricting hopping and/or switch to another scoring method. Complaining about "cheating" when there is no rule won't get anywhere.
** --[[User:Luke-jr|Luke-jr]] 16:16, 27 May 2011 (GMT)
::I continued this [http://forum.bitcoin.org/index.php?topic=10038.msg148710#msg148710 on the forums]. [[User:Holy-Fire|Holy-Fire]] 19:57, 28 May 2011 (GMT)

Mining pool reward FAQ

2011-05-27T12:12:51Z

Holy-Fire: Until we reach some sort of agreement, this should remain in the castrated, uncontentious form

== How does mining in a pool improve my payouts? ==
Pooled mining will not have a significant effect on the [http://en.wikipedia.org/wiki/Expected_value expectation] of your payouts (it can decrease a bit due to fees), but it can dramatically decrease their [http://en.wikipedia.org/wiki/Variance variance].

== What reward systems are there? ==
All reward systems use the concept of "share", a hash which is easier than the real difficulty and proves you have worked on finding a valid block. Your reward when the pool finds a valid block depends on the shares you submitted.

The main reward systems used are:
:'''Pay per share''': Every share submitted receives a fixed BTC reward known in advance. This has virtually 0 variance and is thus good for beginners. The Pool Operator often takes a relatively large fee, due to the fact that they cannot know how much will be paid in total to all the miners.

:'''Proportional''' ("Share-based"): Every time a block is found, its reward is split between participants according to the number of shares they submitted.

:'''Score-based''': Each share submitted receives a score based on its age, and the block reward is split between participants according to their score. The variance of this method is slightly higher than proportional.

== What will be my expected payout per share? ==
Every share will give you, on average, the block reward (minus any pool fees) divided by the difficulty. For example, with a block reward of 50 BTC, 2% fee and difficulty of 240000, each share submitted will give on average 0.000204 BTC (204 μBTC).

== How many hashes does it take to find a share? ==
On average, one share will be found for every 2^32, or 4.295 billion, hashes calculated. So at 1 MHash/s, you will find a share on average every 72 minutes.

== How much will the pool decrease my variance? ==
If you constitute a significant part of the pool (say, above 1%), your variance will be roughly proportional to your portion of the pool. If, for example, you are 20% of the pool, your variance will be 20% of solo mining variance (a decrease factor of 5 times).

If not, your variance will not depend on the size of yourself or the pool, but rather on the scoring method used. For proportional, the decrease factor is roughly difficulty/ln(difficulty). For the geometric method the decrease factor is roughly (1 + 2*difficulty*c), where c is the score fee parameter used.

Increasing the size of the pool will always decrease the variance, but at some point you will have diminishing marginal utility.

Talk:Mining pool reward FAQ

2011-05-27T04:21:58Z

Holy-Fire: /* Pool-hopping */

Talk:Mining pool reward FAQ

2011-05-27T04:17:42Z

Holy-Fire: /* Pool-hopping */

Talk:Mining pool reward FAQ

2011-05-27T04:15:25Z

Holy-Fire: /* Pool-hopping */

Talk:Mining pool reward FAQ

2011-05-27T04:10:39Z

Holy-Fire: /* Pool-hopping */

User talk:Firestorm

2011-05-26T19:25:34Z

Holy-Fire: /* Reward FAQ */

{| style="width:100%;background: #FDFAF8; margin: 0.25em auto; border: 1px solid #C29272; text-align:center; " cellpadding="1" cellspacing="0" rules="all"
| colspan=15 style="font-weight: bold;font-size:135%;"| [http://en.bitcoin.it/w/index.php?title=User_talk:Firestorm&action=edit&section=new Please start a new discussion by clicking here.]
|}

== Reward FAQ ==

Hi Firestorm,
I appreciate your attempt at a compromise with [[Mining pool reward FAQ]], but your edit is wrong for several reasons.
*You have left out important information about which there is no contention, such as the fact that PPS has high fees.
*You have kept a wrong piece of information, "... this method is disadvantageous ...", which as I explained is a myth.
*You have removed information which was contended but is very important.
I have requested that the page be deleted. [[User:Holy-Fire|Holy-Fire]] 19:07, 26 May 2011 (GMT)

:I don't agree that it should be deleted, it could be very helpful. I would like to collaborate with you and Luke to make a better FAQ, I never meant for my edit to be the final edit. --[[User:Firestorm|<tt><big>'''Firestorm'''</big></tt>]] 19:13, 26 May 2011 (GMT)
::Well, I've recreated it as [http://forum.bitcoin.org/index.php?topic=10038.0 a forum post] so the information is still there.
::I know from the outside it may look like there are two points of view here, but (and you'll forgive me for my lack of false modesty) there really aren't - there are those who know what they're talking about, and those who don't. As you can see Luke-jr has ignored my solicitation for discussion and opted to go for an edit war. There's no way we can possibly resolve this, and frankly I prefer to just point people to a forum post which I know will contain accurate information. [[User:Holy-Fire|Holy-Fire]] 19:22, 26 May 2011 (GMT)
::BTW, it makes very little sense to talk about score-based payouts without mentioning the problem they are designed to solve. [[User:Holy-Fire|Holy-Fire]] 19:25, 26 May 2011 (GMT)
::: I understand your viewpoint and agree that Luke should be in contact with us. We CAN, in fact, resolve this. Keep the FAQ as a barebones FAQ, with only limited info, and direct to the Forum post. If Luke refuses to listen to reason, we can get a Mod/Admin to resolve this. Man, I wish I had my mod powers here! --[[User:Firestorm|<tt><big>'''Firestorm'''</big></tt>]] 19:24, 26 May 2011 (GMT)

Mining pool reward FAQ

2011-05-26T19:24:27Z

Holy-Fire: /* What reward systems are there? */ If you remove contended information, remove it all

User talk:Firestorm

2011-05-26T19:22:38Z

Holy-Fire: /* Reward FAQ */

User talk:Firestorm

2011-05-26T19:09:40Z

Holy-Fire: /* Reward FAQ */

User talk:Nanotube

2011-05-26T19:08:28Z

Holy-Fire:

Hi Nanotube,
can you please delete [[Mining pool reward FAQ]]? I created it to provide information about some commonly confused issues, but it's being abused and thus can't serve this purpose. [[User:Holy-Fire|Holy-Fire]] 18:43, 26 May 2011 (GMT)
: I removed the troublesome content and left it to-the-point. This should serve to remove any abuse. --[[User:Firestorm|<tt><big>'''Firestorm'''</big></tt>]] 18:51, 26 May 2011 (GMT)
::Sorry, it really doesn't, see my comment on your talk page. [[User:Holy-Fire|Holy-Fire]] 19:08, 26 May 2011 (GMT)

User talk:Firestorm

2011-05-26T19:07:43Z

Holy-Fire: /* Reward FAQ */ new section

User talk:Nanotube

2011-05-26T18:43:32Z

Holy-Fire: Deleting Mining pool reward FAQ

Mining pool reward FAQ

2011-05-26T14:47:11Z

Holy-Fire: /* What reward systems are there? */ + does hopping take place?

== How does mining in a pool improve my payouts? ==
Pooled mining will not have a significant effect on the [http://en.wikipedia.org/wiki/Expected_value expectation] of your payouts (it can decrease a bit due to fees), but it can dramatically decrease their [http://en.wikipedia.org/wiki/Variance variance].

== What reward systems are there? ==
All reward systems use the concept of "share", a hash which is easier than the real difficulty and proves you have worked on finding a valid block. Your reward when the pool finds a valid block depends on the shares you submitted.

The main reward systems used are:
:'''Pay per share''': Every share submitted receives a fixed BTC reward known in advance. This has virtually 0 variance and is thus good for beginners. However, the operator is subject to enormous variance, and will thus take a large fee to cover his risk. This means the expectation for participants is low, so it's not an attractive long-term solution.
:It is also vulnerable to sabotage where the miner simply withholds all block-finding shares, causing a loss to the pool operator.

:'''Proportional''' ("Share-based"): Every time a block is found, its reward is split between participants according to the number of shares they submitted. This method is vulnerable to a form of cheating known as "pool-hopping". In the theoretical limit, this can reduce the payout for honest participants by up to 30% (in practice the decrease would be much less, but can still be significant).
:It is not known whether pool-hopping has already been implemented.

:'''Score-based''': Each share submitted receives a score based on its age, and the block reward is split between participants according to their score. The method used by slush's pool and BTCmine are resistant to pool-hopping, while the one used by Continuum pool ("geometric method") is completely immune.
:The variance of this method is slightly higher than proportional.
:There is a myth that score-based is disadvantageous if you only mine several hours a day or disconnect in the middle of the round. In fact the expectation (which is the more important part) is exactly the same, and only the variance can slightly increase. The shares already submitted will depreciate the same way whether you disconnect or not, and the newer shares will have the same expectation for any reward method.

== What will be my expected payout per share? ==
Every share will give you, on average, the block reward (minus any pool fees) divided by the difficulty. For example, with a block reward of 50 BTC, 2% fee and difficulty of 240000, each share submitted will give on average 0.000204 BTC (204 μBTC).

== How many hashes does it take to find a share? ==
On average, one share will be found for every 2^32, or 4.295 billion, hashes calculated. So at 1 MHash/s, you will find a share on average every 72 minutes.

== How much will the pool decrease my variance? ==
If you constitute a significant part of the pool (say, above 1%), your variance will be roughly proportional to your portion of the pool. If, for example, you are 20% of the pool, your variance will be 20% of solo mining variance (a decrease factor of 5 times).

If not, your variance will not depend on the size of yourself or the pool, but rather on the scoring method used. For proportional, the decrease factor is roughly difficulty/ln(difficulty). For the geometric method the decrease factor is roughly (1 + 2*difficulty*c), where c is the score fee parameter used.

Increasing the size of the pool will always decrease the variance, but at some point you will have diminishing marginal utility.