Bitcoin Wiki - User contributions [en]

Cryptocurrent

2013-04-08T04:05:23Z

Alvox: Add Twitter and spot price

'''Cryptocurrent''' is a bitcoin [[currency exchange]] site launched in March 2013 by JonSnow, serving the United States market.

==Adding Funds==
Cash (USD) can be deposited in person via Wells Fargo and Bank of America, or USPS/FedEx mail with prepaid label. CryptoCurrent takes a 5% fee over the [[MtGox]] Last or MtGox Weighted Average, whichever is higher at the time of processing.

==Reviews==
Cryptocurrent has received unanimously positive reviews, praising its speed and customer support.<ref>[https://bitcointalk.org/index.php?topic=151656.msg1609825#msg1609825 Review by battmann]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1664345#msg1664345 Review by Immuzikation]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1694976#msg1694976 Review by ConcernedCoins]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1696780#msg1696780 Review by opentoe]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1702801#msg1702801 Review by Severian]</ref>

==History==
The exchange had been operating since August 2012 informally, with its first publicity occurring on March 11, 2013<ref name="FirstForumPost">[https://bitcointalk.org/index.php?topic=151656.0 CryptoCurrent // Bitcoin Sales - Simple & Secure]</ref>.

As of April 7, 2013, 11:42pm EDT, Cryptocurrent is down for maintenance.<ref>[http://www.webcitation.org/6FiV4gt5V WebCitation snapshot of Cryptocurrent as of 2013-04-07 23:42 EDT]</ref>

==See Also==

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

==External Links==

* [https://cryptocurrent.com CryptoCurrent] website
* [https://twitter.com/crypto_current Twitter page]

==References==
<References />

[[Category:Exchanges]]
[[Category:EWallets]]

Cryptocurrent

2013-04-08T03:56:02Z

Alvox: Let there be page

'''Cryptocurrent''' is a bitcoin [[currency exchange]] site launched in March 2013 by JonSnow, serving the United States market.

==Adding Funds==
Cash (USD) can be deposited in person via Wells Fargo and Bank of America, or USPS/FedEx mail with prepaid label. CryptoCurrent takes a 5% fee.

==Reviews==
Cryptocurrent has received unanimously positive reviews, praising its speed and customer support.<ref>[https://bitcointalk.org/index.php?topic=151656.msg1609825#msg1609825 Review by battmann]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1664345#msg1664345 Review by Immuzikation]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1694976#msg1694976 Review by ConcernedCoins]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1696780#msg1696780 Review by opentoe]</ref>
<ref>[https://bitcointalk.org/index.php?topic=151656.msg1702801#msg1702801 Review by Severian]</ref>

==History==
The exchange had been operating since August 2012 informally, with its first publicity occurring on March 11, 2013<ref name="FirstForumPost">[https://bitcointalk.org/index.php?topic=151656.0 CryptoCurrent // Bitcoin Sales - Simple & Secure]</ref>.

As of April 7, 2013, 11:42pm EDT, Cryptocurrent is down for maintenance.<ref>[http://www.webcitation.org/6FiV4gt5V WebCitation snapshot of Cryptocurrent as of 2013-04-07 23:42 EDT]</ref>

==See Also==

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

==External Links==

* [https://cryptocurrent.com CryptoCurrent] website

==References==
<References />

[[Category:Exchanges]]
[[Category:EWallets]]

Bitfloor

2013-04-08T02:30:24Z

Alvox: /* History */ Added downtime and no repayment after the 24k BTC breach

A bitcoin [[currency exchange]]/trading platform site headquartered in USA - State of New York.

==Adding Funds==
Funds deposited with the exchange for escrow towards placing a buy order include the following.

===BTC===

* Adding bitcoins to the account balance incurs no fees.

===USD===

* In-person cash deposit through Bank of America
* Bank wire transfer
* CapitalOne 360 P2p (formerly ING Person2Person)

==Withdrawing Funds==

===BTC===

* There are no fees for Bitcoin withdrawals.

===USD===

* ACH Bank withdrawal (Direct deposit)

==Trading==

Trades on the exchange incur a commission (fee). Providers of liquidity receive a rebate giving those offers a price advantage over those trading at market.

==Features==
The exchange offers a REST API for automated trading

The exchange offers a FIX (Financial Information Exchange) order entry gateway for automated trading<ref>[http://bitcointalk.org/index.php?topic=66045.0 FIX gateway available on bitfloor.com]</ref>.

==History==

The exchange had been operating since 2011 with its first publicity occurring in February 2012<ref>[http://www.youtube.com/watch?v=F7SsavHX6tc The Bitcoin Show - 056 - Roman Shtylman of Bitfloor.com]</ref>.

On September 4, 2012 the operator of BitFloor reported a security breach that resulted in the exchange's wallet with '''24K BTC being stolen'''. The site was shuttered and access to customer funds denied as the exchange's reserves were insufficient to accommodate all funds deposited. As of March 8, 2013, 3 months had passed since the last repayment (December 2012), and the operator had been unresponsive.<ref>[https://bitcointalk.org/index.php?topic=144509.msg1599788#msg1599788 It's been 3 months since the first BTC re-payment in early December.]</ref>

On April 3, 2012, the website was down for several minutes.<ref>[https://bitcointalk.org/index.php?topic=166254.0 bitfloor down?!]</ref>

BitFloor is a Money Service Business (MSB) registered with FinCEN (#31000005224108).

==See Also==

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

==External Links==

* [https://bitfloor.com BitFloor] website
* [https://github.com/bitfloor github] page
* [http://bitcoincharts.com/charts/chart.png?width=940&m=bitfloorUSD&SubmitButton=Draw&r=60&i=&c=0&s=&e=&Prev=&Next=&t=S&b=&a1=&m1=10&a2=&m2=25&x=0&i1=&i2=&i3=&i4=&v=1&cv=0&ps=0&l=0&p=0& Chart]

==References==
<References />

[[Category:Exchanges]]
[[Category:EWallets]]

Bets of Bitcoin

2013-04-07T11:35:45Z

Alvox: Add criticism

'''Bets of Bitcoin''' is a [[wikipedia:prediction market|prediction market]] where users can bet on the outcome of future real world events.

Bet results are decided by the site moderators. The winners will get their wagers back plus will earn the wagers from those that lost (less a small commission paid to the site).

The returns will vary for the winners though as bets are time-weighted and there is a premium earned for those who place their wagers earlier versus those place a bet later.

Anyone can create a bet statement, though new bets are vetted to eliminate bets whose outcome can't be easily determined or is easily manipulated and for bets that the site moderators would rather not see listed. The site pays half of the commission it receives to the person that created the bet statement.

When adding funds to the account with the site (an [[EWallet]]), deposits are credited after three confirmations<ref>[http://bitcointalk.org/index.php?topic=37069.msg726999#msg726999 How many confirmations]</ref>.

==History==

The service was launched on August 14, 2011<ref>[http://bitcointalk.org/index.php?topic=37069.0 Bets of Bitcoin - Bitcoin betting on real world events]</ref>. On April 18th, 2012 there was nearly $5,000 USD worth of open bets on the site.{{citation needed}}

==Criticism==
Junk submissions<ref>[https://betsofbitcoin.uservoice.com/forums/130083-general/suggestions/3804619-aaaa good]</ref><ref>[https://betsofbitcoin.uservoice.com/forums/130083-general/suggestions/3804619-aaaa aaaa]</ref> for '''Bets of Bitcoin''' on user feedback management site [https://betsofbitcoin.uservoice.com/forums/130083-general Uservoice] show that the operators do not read users' feedback. The site does not offer a profit<ref name="topreq">[https://betsofbitcoin.uservoice.com/forums/130083-general/filters/top Top requests on Uservoice]</ref> or bet payout calculator, and there is no way to recover a forgotten password<ref name="topreq" />. One request alleges that the website hasn't paid out winners of a certain bet.<ref>[https://betsofbitcoin.uservoice.com/forums/130083-general/suggestions/3806479-wherer-are-the-money wherer are the money]</ref>

==External Links==

* [http://betsofbitco.in/ Bets of Bitcoin] Official website
* [http://www.reddit.com/r/betsofbitcoin /r/betsofbitcoin] reddit for discussion of the site or any bets.

==References==
<references />

[[Category:Gambling]]
[[Category:EWallets]]
[[Category:Predictions Markets]]

Bitcoin

2013-04-07T10:59:21Z

Alvox: Update market cap

'''Bitcoin''' is a decentralized [[digital currency]] created by developer [[Satoshi Nakamoto]]. It does not rely on a central server to process transactions or store funds. There are a maximum of 2,100,000,000,000,000 Bitcoin elements (called satoshis), currently most commonly measured in units of 100,000,000 known as BTC.

{{As of|April 2013}}, it is the most widely used alternative currency,<ref name="Quantitative Analysis of the Full Bitcoin Transaction Graph">{{cite web|title=Quantitative Analysis of the Full Bitcoin Transaction Graph|url=http://eprint.iacr.org/2012/584.pdf|publisher=Cryptology ePrint Archive|accessdate=18 October 2012|author=Ron Dorit|coauthors=Adi Shamir|page=17|quote=The Bitcoin system is the best known and most widely used alternative payment scheme,...}}</ref><ref name="Mt.Gox data">{{Cite web|title=Mt.Gox data|url=http://bitcoincharts.com/markets/mtgoxUSD.html|publisher=Bitcoincharts}}</ref> with the total market cap at over 1.5 bilion US dollars<ref>{{cite web|title=Market Capitalization|url=http://blockchain.info/charts/market-cap|publisher=Blockchain.info|accessdate=7 April 2013}}</ref>.

Bitcoin has no central issuer; instead, the peer-to-peer network regulates Bitcoins, transactions and issuance according to consensus in network software.
Bitcoins are issued to various nodes that verify transactions through computing power;
it is established that there will be a limited and scheduled release of no more than 21 million BTC worth of coins, which will be fully issued by the year 2140.

Internationally, Bitcoins can be exchanged and managed through various websites and [[software]] along with physical banknotes and coins.<ref>{{Cite web|title=Physical Bitcoins by Casascius|url=https://www.casascius.com/|publisher=Casascius Coins|accessdate=29 September 2012}}</ref><ref>{{Cite web|title=Bitbills|url=http://www.bitbills.com/|publisher=Bitbills|accessdate=29 September 2012}}</ref>

==History==
:Main article: [[History]]

A cryptographic system for untraceable payments was first described by David Chaum in 1982.<ref>[http://blog.koehntopp.de/uploads/Chaum.BlindSigForPayment.1982.PDF David Chaum, Blind signatures for untraceable payments], Advances in Cryptology - Crypto '82, Springer-Verlag (1983), 199–203.</ref> In 1990 Chaum extended this system to create the first cryptographic anonymous electronic cash system.,<ref>{{cite journal|journal=Lecture Notes in Computer Science|last1=Chaum|first1=David|last2=Fiat|first2=Amos|last3=Naor|first3=Moni|title=Untraceable Electronic Cash|url=http://blog.koehntopp.de/uploads/chaum_fiat_naor_ecash.pdf}}</ref> which became known as ecash.
<ref>{{cite web|url=http://www.wired.com/wired/archive/2.12/emoney.html|publisher=Wired|title=E-Money (That's What I Want)|date=1994–2012|author=Steven Levy}}</ref> In 1998 Wei Dai published a description of an anonymous, distributed electronic cash system which he called "b-money".<ref>{{cite web|title=B-Money|url=http://www.weidai.com/bmoney.txt|author=Wei Dai|year=1998}}</ref> Around the same time, Nick Szabo created ''bit gold''.<ref>{{cite web|url=http://spectrum.ieee.org/computing/software/bitcoin-the-cryptoanarchists-answer-to-cash/0|title=Bitcoin: The Cryptoanarchists’ Answer to Cash|publisher=IEEE Spectrum|quote=Around the same time, Nick Szabo, a computer scientist who now blogs about law and the history of money, was one of the first to imagine a new digital currency from the ground up. Although many consider his scheme, which he calls “bit gold,” to be a precursor to Bitcoin}}</ref><ref name="bitgold">{{cite web|title=Bit gold|url=http://unenumerated.blogspot.co.uk/2005/12/bit-gold.html|author=Nick Szabo|quote=My proposal for bit gold is based on computing a string of bits from a string of challenge bits, using functions called variously "client puzzle function," "proof of work function," or "secure benchmark function.". The resulting string of bits is the proof of work.... The last-created string of bit gold provides the challenge bits for the next-created string.}}</ref> Like Bitcoin, ''Bit gold'' was a currency system where users would compete to solve a [[proof of work]] function, with solutions being cryptographically chained together and published via a distributed property title registry. A variant of ''Bit gold'', called ''Reusable Proofs of Work'', was implemented by Hal Finney.<ref name="bitgold"/>

In 2008, Satoshi Nakamoto published a paper<ref name="whitepaper">{{cite web
|last= Nakamoto
|first= Satoshi
|title= Bitcoin: A Peer-to-Peer Electronic Cash System
|url= http://www.cs.kent.edu/~JAVED/class-P2P12F/papers-2012/PAPER2012-p2p-bitcoin-satoshinakamoto.pdf
|accessdate = 14 December 2010
|date= 24 May 2009
|postscript=
}}</ref><ref>{{cite web
|url= http://article.gmane.org/gmane.comp.encryption.general/12588/
|title= Bitcoin P2P e-cash paper
}}</ref> on The Cryptography Mailing list at metzdowd.com<ref>[http://www.mail-archive.com/search?l=cryptography@metzdowd.com&q=from:%22Satoshi+Nakamoto%22 Satoshi's posts to Cryptography mailing list]</ref> describing the Bitcoin protocol.

The Bitcoin network came into existence on 3 January 2009 with the release of the first Bitcoin client, [[wxBitcoin]], and the issuance of the first Bitcoins.<ref>{{cite web |title=Block 0 – Bitcoin Block Explorer |url=http://blockexplorer.com/block/000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f }}</ref><ref>{{cite web |url=http://www.mail-archive.com/cryptography@metzdowd.com/msg10142.html |title=Bitcoin v0.1 released}}</ref><ref>{{cite web |url=http://sourceforge.net/news/?group_id=244765 |title=SourceForge.net: Bitcoin}}</ref>
A year after, the initial exchange rates for Bitcoin were set by individuals on the bitcointalk forums.{{Citation needed|date=October 2012}} The most significant transaction involved a 10,000 BTC pizza.<ref>{{cite web|title=The Rise and Fall of Bitcoin|url=http://www.wired.com/magazine/2011/11/mf_bitcoin/|publisher=Wired|accessdate=13 October 2012}}</ref>
Today, the majority of Bitcoin exchanges occur on the [[MtGox]] Bitcoin exchange.

In 2011, Wikileaks,<ref>{{cite news
|last= Greenberg
|first= Andy
|url= http://blogs.forbes.com/andygreenberg/2011/06/14/wikileaks-asks-for-anonymous-bitcoin-donations/
|title= WikiLeaks Asks For Anonymous Bitcoin Donations – Andy Greenberg – The Firewall – Forbes
|publisher= Blogs.forbes.com
|date= 2011-06-14
|accessdate = 2011-06-22
}}</ref> [[Freenet]],<ref>{{cite web
|url= https://freenetproject.org/donate.html
|title= /donate
|publisher= The Freenet Project
|date=
|accessdate = 2011-06-22
}}</ref> Singularity Institute,<ref>[http://singinst.org/donate/ SIAI donation page]</ref> Internet Archive,<ref>[http://www.archive.org/donate/index.php Internet Archive donation page]</ref> Free Software Foundation<ref>[https://my.fsf.org/donate/other/ Other ways to donate]</ref> and others, began to accept donations in Bitcoin. The Electronic Frontier Foundation did so for a while but has since stopped, citing concerns about a lack of legal precedent about new currency systems, and because they "generally don't endorse any type of product or service."<ref>{{cite web
|url= https://www.eff.org/deeplinks/2011/06/eff-and-bitcoin
|title= EFF and Bitcoin | Electronic Frontier Foundation
|publisher= Eff.org
|date= 2011-06-14
|accessdate = 2011-06-22
}}</ref> Some small businesses had started to adopt Bitcoin. LaCie, a public company, accepts Bitcoin for its Wuala service.<ref>{{Cite web|url=http://www.wuala.com/en/bitcoin |title=Secure Online Storage – Backup. Sync. Share. Access Everywhere |publisher=Wuala |date= |accessdate = 2012-01-24}}</ref>

In 2012, BitPay reports of having over 1000 merchants accepting Bitcoin under its payment processing service.<ref>{{cite web|title=BitPay Signs 1,000 Merchants to Accept Bitcoin Payments|url=http://www.americanbanker.com/issues/177_176/bitpay-signs-1000-merchants-to-accept-bitcoin-payments-1052538-1.html|publisher=American Banker|accessdate=12 October 2012}}</ref>

==Administration==
Bitcoin is administered through a decentralized peer-to-peer network.<ref name="whitepaper"/> Cryptographic technologies and the peer-to-peer network of computing power enables users to make and verify irreversible, instant online Bitcoin payments, without an obligation to trust and use centralized banking institutions and authorities. Dispute resolution services are not made directly available. Instead it is left to the users to verify and trust the parties they are sending money to through their choice of methods.

Bitcoins are issued according to rules agreed to by the majority of the computing power within the Bitcoin network. The core rules describing the predictable issuance of Bitcoins to its verifying servers, a voluntary and competitive transaction fee system and the hard limit of no more than 21 million BTC issued in total.<ref name="whitepaper"/>

Bitcoin does not require a central bank, State,<ref>{{cite web
|url= http://spectrum.ieee.org/computing/software/bitcoin-the-cryptoanarchists-answer-to-cash/3
|title= Bitcoin: The Cryptoanarchists' Answer to Cash
|publisher= IEEE.org
|date= June 2012
|accessdate = 2012-06-05
}}</ref> or incorporated backers.

==Services==
:Main article: [[Wallet]]

Bitcoins are sent and received through software and websites called wallets. They send and confirm transactions to the network through Bitcoin addresses, the identifiers for users' Bitcoin wallets within the network.<ref name="whitepaper"/>

===Bitcoin addresses===
:Main article: [[Address]]

Payments are made to Bitcoin "addresses": human-readable strings of numbers and letters around 33 characters in length, always beginning with the digit 1 or 3, as in the example of ''31uEbMgunupShBVTewXjtqbBv5MndwfXhb''.

Users obtain new Bitcoin addresses from their Bitcoin software. Creating a new address can be a completely offline process and require no communication with the Bitcoin network.

===Transaction fees===
:Main article: [[Transaction fees]]
Transaction fees may be included with any transfer of Bitcoins. {{As of|2012}} many transactions are processed in a way which makes no charge for the transaction. For transactions which consume or produce many coins (and therefore have a large data size), a small transaction fee is usually expected.

===Confirmations===
:Main article: [[Confirmation]]

The network's software confirms a transaction when it records it in a block. Further blocks of transactions confirm it even further. After six confirmations/blocks, a transaction is confirmed beyond reasonable doubt.

The network must store the whole transaction history inside the blockchain, which grows constantly as new records are added and never removed. Nakamoto conceived that as the database became larger, users would desire applications for Bitcoin that didn't store the entire database on their computer. To enable this, the blockchain uses a [[merkle tree]] to organize the transaction records in such a way that client software can locally delete portions of its own database it knows it will never need, such as earlier transaction records of Bitcoins that have changed ownership multiple times.

==Economics==

===Initial distribution===

Bitcoin has no centralized issuing authority.<ref name="ars-06-08-11">
{{Cite news
|first= Thomas
|last= Lowenthal
|title= Bitcoin: inside the encrypted, peer-to-peer digital currency
|newspaper= Ars Technica
|date= 8 June 2011
|url= http://arstechnica.com/tech-policy/news/2011/06/bitcoin-inside-the-encrypted-peer-to-peer-currency.ars
}}</ref><ref>{{cite news
|author= Sponsored by
|url= http://www.economist.com/blogs/babbage/2011/06/virtual-currency
|title= Virtual currency: Bits and bob
|publisher= The Economist
|date=
|accessdate = 2011-06-22
}}</ref><ref>{{cite web
|last= Geere
|first= Duncan
|url= http://www.wired.co.uk/news/archive/2011-05/16/bitcoin-p2p-currency
|title= Peer-to-peer currency Bitcoin sidesteps financial institutions (Wired UK)
|publisher= Wired.co.uk
|date=
|accessdate = 2011-06-22
}}</ref> The network is programmed to increase the money supply as a geometric series until the total number of Bitcoins reaches 21 million BTC.<ref name="Quantitative Analysis of the Full Bitcoin Transaction Graph"/> {{As of|2012|10}} slightly over 10 million of the total 21 million BTC had been created; the current total number created is available online.<ref>{{cite web
|title= Total Number of Bitcoins in Existence
|url= http://blockexplorer.com/q/totalbc
|work= Bitcoin Block Explorer
|accessdate = 2012-10-03
}}</ref> By 2013 half of the total supply will have been generated, and by 2017, three-quarters will have been generated. To ensure sufficient granularity of the [[money supply]], clients can divide each BTC unit down to eight decimal places (a total of 2.1 × 10<sup>15</sup> or 2.1 quadrillion units).<ref name="lwn">{{Cite news
|author= Nathan Willis
|date= 2010-11-10
|title= Bitcoin: Virtual money created by CPU cycles
|publisher= LWN.net
|url= http://lwn.net/Articles/414452/
}}</ref>

The network {{As of|2012|lc=on}} required over one million times more work for confirming a block and receiving an award (25 BTC {{As of|2012|2|lc=on}}) than when the first blocks were confirmed.
The difficulty is automatically adjusted every 2016 blocks based on the time taken to find the previous 2016 blocks such that one block is created roughly every 10 minutes.

Those who chose to put computational and electrical resources toward mining early on had a greater chance at receiving awards for block generations. This served to make available enough processing power to process blocks. Indeed, without miners there are no transactions and the Bitcoin economy comes to a halt.

===Exchange rate===
Prices fluctuate relative to goods and services more than more widely accepted currencies;
the price of a Bitcoin is not static.

In August 2012, 1 BTC traded at around $10.00 USD. Taking into account the total number of Bitcoins mined, the monetary base of the Bitcoin network stands at over 110 million USD.<ref>[http://www.bitcoinwatch.com/ http://www.bitcoinwatch.com/] Bitcoin statistics</ref>

== Security ==
:Main article: [[Weaknesses]]

In the history of bitcoin, there have been a few [[incidents]], caused by problematic as well as malicious transactions. In the worst such incident, and the only one of its type, a person was able to pretend that he had a practically infinite supply of bitcoins, for almost 9 hours.

Bitcoin relies, among other things, on [http://en.wikipedia.org/wiki/Public-key_cryptography public key cryptography] and thus may be vulnerable to [http://en.wikipedia.org/wiki/Elliptic_curve_cryptography#Quantum_computing_attacks quantum computing attacks] if and when practical quantum computers can be constructed.

If multiple different software packages, whose usage becomes widespread on the Bitcoin network, disagree on the protocol and the rules for transactions, this could potentially cause a fork in the block chain, with each faction of users being able to accept only their own version of the history of transactions. This could influence the price of bitcoins.

A global, organized campaign against the currency or the software could also influence the demand for bitcoins, and thus the exchange price.

==Bitcoin mining==
:Main article: [[Mining]]

Bitcoin mining nodes are responsible for managing the Bitcoin network.

Bitcoins are awarded to Bitcoin nodes known as "miners" for the solution to a difficult [[proof-of-work]] problem which confirms transactions and prevents double-spending. This incentive, as the Nakamoto white paper describes it, encourages "nodes to support the network, and provides a way to initially distribute coins into circulation, since no central authority issues them."<ref name="whitepaper" />

Nakamoto compared the generation of new coins by expending CPU time and electricity to gold miners expending resources to add gold to circulation.<ref name="whitepaper"/>

===Node operation===

The node software for the Bitcoin network is based on peer-to-peer networking, digital signatures and cryptographic proof to make and verify transactions. Nodes broadcast transactions to the network, which records them in a public record of all transactions, called the ''blockchain'', after validating them with a [[proof-of-work|proof-of-work system]].

Satoshi Nakamoto designed the first Bitcoin node and mining software<ref name="processors">{{Cite news
|last= Davis
|first= Joshua
|title= The Crypto-Currency
|url= http://www.wired.com/magazine/2011/11/mf_bitcoin/all
|accessdate = 11 November 2011
|newspaper= Wired Magazine
|date= 10 November 2011
}}</ref> and developed the majority of the first implementation, Bitcoind, from 2007 to mid-2010.<ref name="code_start">{{cite web
|url= https://bitcointalk.org/index.php?topic=13.msg46#msg46
|title= Questions about Bitcoin
|publisher= Bitcoin forum
|date= 2009-12-10
}}</ref>

Node implementations include core software such as Bitcoind/Bitcoin-Qt, [[libbitcoin]], [[cbitcoin]]<ref>{{Cite web|title=cbitcoin|url=https://github.com/MatthewLM/cbitcoin|accessdate=3 October 2012}}</ref> and [[BitCoinJ|bitcoinj]].<ref>{{cite web
|url= http://news.slashdot.org/story/11/03/23/0210207/Google-Engineer-Releases-Open-Source-Bitcoin-Client
|title= Google Engineer Releases Open Source Bitcoin Client
|author= angry tapir, timothy
|date= 23 March 2011
|publisher= Slashdot
|accessdate = 2011-05-18
}}</ref><ref>{{cite web
|url= http://www.javaworld.com/javaworld/jw-01-2012/120110-bitcoin-for-beginners-3.html?page=1
|title= Bitcoin for beginners: The BitcoinJ API
|author= Dirk Merkel
|date= 10 January 2012
|publisher= JavaWorld
|accessdate = 2012-08-03
}}</ref>

Every node in the Bitcoin network collects all the unacknowledged transactions it knows of in a file called a ''block'', which also contains a reference to the previous valid block known to that node. It then appends a [[nonce]] value to this previous block and computes the SHA-256 cryptographic hash of the block and the appended nonce value. The node repeats this process until it adds a nonce that allows for the generation of a hash with a value lower than a specified ''target''. Because computers cannot practically reverse the hash function, finding such a nonce is hard and requires on average a predictable amount of repetitious trial and error. This is where the ''[[proof-of-work]]'' concept comes in to play. When a node finds such a solution, it announces it to the rest of the network. Peers receiving the new solved block validate it by computing the hash and checking that it really starts with the given number of zero bits (i.e., that the hash is within the target). Then they accept it and add it to the chain.

===Mining rewards===
In addition to receiving the pending transactions confirmed in the block, a generating node adds a ''generate'' transaction, which awards new Bitcoins to the operator of the node that generated the block. The system sets the payout of this generated transaction according to its defined inflation schedule. The miner that generates a block also receives the fees that users have paid as an incentive to give particular transactions priority for faster confirmation.

The network never creates more than a 50 BTC reward per block and this amount will decrease over time towards zero, such that no more than 21 million BTC will ever exist.<ref name="lwn" /> As this payout decreases, the incentive for users to run block-generating nodes is intended to change to earning [[#Transaction fees|transaction fees]].

===Mining pools===
:Main article: [[Pooled mining]]

Bitcoin users often pool computational effort to increase the stability of the collected fees and subsidy they receive.<ref name="We Use Coins Mining">{{cite web|title=About Bitcoin Mining|url=http://www.weusecoins.com/mining-guide.php|publisher=We Use Coins|accessdate=18 October 2012}}</ref>

===Mining difficulty===
:Main article: [[Difficulty]]

In order to throttle the creation of blocks, the difficulty of generating new blocks is adjusted over time. If mining output increases or decreases, the difficulty increases or decreases accordingly.

The adjustment is done by changing the threshold that a hash is required to be less than. A lower threshold means fewer possible hashes can be accepted, and thus a higher degree of difficulty. The target rate of block generation is one block every 10 minutes, or 2016 blocks every two weeks. Bitcoin changes the difficulty of finding a valid block every 2016 blocks, using the difficulty that would have been most likely to cause the prior 2016 blocks to have taken two weeks to generate, according to the timestamps on the blocks. Technically, this is done by modeling the generation of Bitcoins as Poisson process. All nodes perform and enforce the same difficulty calculation.

Difficulty is intended as an automatic stabilizer allowing mining for Bitcoins to remain profitable in the long run for the most efficient miners, independently of the fluctuations in demand of Bitcoin in relation to other currencies.

===Mining hardware===
:Main article: [[Mining Hardware Comparison]]

Bitcoins used to be mined through Intel/AMD CPUs. {{As of | 2012}}, mining has gradually moved to [[GPU]] and [[FPGA]] hardware.<ref name="bitcoinmag-butterfly" /> [[Application-specific integrated circuit|ASIC]]-based hardware for Bitcoin mining has been announced by several manufacturers who intend to ship products from late 2012 to early 2013.<ref name="bitcoinmag-butterfly">{{Cite web|title=Bitpay Breaks Daily Volume Record with Butterfly ASIC mining release|url=http://bitcoinmagazine.net/bitpay-breaks-daily-volume-record-with-butterfly-asic-mining-release/|publisher=Bitcoin Magazine}}</ref>

==Concerns==

===As an investment===
Bitcoin describes itself as an experimental digital currency. Reuben Grinberg has noted that Bitcoin's supporters have argued that Bitcoin is neither a security or an investment because it fails to meet the criteria for either category.<ref name="grinberg">{{cite web | url=http://papers.ssrn.com/sol3/papers.cfm?abstract_id=1817857 | title=Bitcoin: An Innovative Alternative Digital Currency | publisher=SSRN | date=9 December 2011 | accessdate=4 December 2012 | author=Grinberg, Reuben}}</ref> Although it is a virtual currency, some people see it as an investment<ref name="cnbc">{{cite web | url=http://www.cnbc.com/id/45030812/The_Pros_And_Cons_Of_Biting_on_Bitcoins | title=The Pros And Cons Of Biting on Bitcoins | publisher=CNBC | date=23 November 2011 | accessdate=4 December 2012 | author=Gustke, Constance}}</ref> or accuse it of being a form of investment fraud known as a Ponzi scheme.<ref>{{cite web |url=http://www.theregister.co.uk/2011/06/08/bitcoin_under_attack/ |title=US senators draw a bead on Bitcoin |last1=Chirgwin |first1=Richard |date=8 June 2011 |publisher=The Register |accessdate=14 November 2012}}</ref><ref>{{cite web |url=http://uk.reuters.com/article/2012/04/01/uk-traders-bitcoin-idUKBRE8300JL20120401 |title=Bitcoin, the City traders' anarchic new toy |last1=O'Leary |first1=Naomi |date=2 April 2012 |publisher=Reuters |accessdate=14 November 2012}}</ref> A report by the European Central Bank, using the U.S. Securities and Exchange Commission's definition of a Ponzi scheme, found that the use of bitcoins shares some characteristics with Ponzi schemes, but also has characteristics of its own which contradict several common aspects of Ponzi schemes.<ref name="ecbreport">{{cite web | url=http://www.ecb.europa.eu/pub/pdf/other/virtualcurrencyschemes201210en.pdf | title=Virtual Currency Schemes | publisher=European Central Bank | date=October 2012 | accessdate=4 December 2012}}</ref>

===Privacy===
Because transactions are broadcast to the entire network, they are inherently public. Unlike regular banking,<ref>{{cite web
|url= http://spectrum.ieee.org/computing/software/bitcoin-the-cryptoanarchists-answer-to-cash/0
|title= Bitcoin: The Cryptoanarchists' Answer to Cash
|publisher= IEEE.org
|date= June 2012
|accessdate = 2012-06-05
}}</ref> which preserves customer privacy by keeping transaction records private, loose transactional privacy is accomplished in Bitcoin by using many unique addresses for every wallet, while at the same time publishing all transactions. As an example, if Alice sends 123.45 BTC to Bob, the network creates a public record that allows anyone to see that 123.45 has been sent from one address to another. However, unless Alice or Bob make their ownership of these addresses known, it is difficult for anyone else to connect the transaction with them. However, if someone connects an address to a user at any point they could follow back a series of transactions as each participant likely knows who paid them and may disclose that information on request or under duress.

It can be difficult to associate Bitcoin identities with real-life identities.<ref name="An Analysis of Anonymity in the Bitcoin System">Fergal Reid and Martin Harrigan (24 July 2011). [http://anonymity-in-bitcoin.blogspot.com/2011/07/bitcoin-is-not-anonymous.html An Analysis of Anonymity in the Bitcoin System]. An Analysis of Anonymity in the Bitcoin System.</ref> This property makes Bitcoin transactions attractive to sellers of illegal products.<ref name="Forbes">Andy Greenberg (20 April 2011). [http://www.forbes.com/forbes/2011/0509/technology-psilocybin-bitcoins-gavin-andresen-crypto-currency.html Crypto Currency]. Forbes Magazine.</ref><ref>{{cite web
|last= Madrigal
|first= Alexis
|title= Libertarian Dream? A Site Where You Buy Drugs With Digital Dollars
|publisher= The Atlantic Monthly
|date= 2011-06-01
|url= http://www.theatlantic.com/technology/archive/2011/06/libertarian-dream-a-site-where-you-buy-drugs-with-digital-dollars/239776/
|accessdate = 2011-06-05
}}</ref>

===Illicit use===

====Cracking====
The cracking organization "LulzSec" accepted donations in Bitcoin, having said that the group "needs Bitcoin donations to continue their hacking efforts".<ref name="CNET">{{cite web
|last= Reisinger
|first= Don
|url= http://news.cnet.com/8301-13506_3-20070268-17/senators-target-bitcoin-currency-citing-drug-sales/
|title= Senators target Bitcoin currency, citing drug sales | The Digital Home – CNET News
|publisher= News.cnet.com
|date= 2011-06-09
|accessdate = 2011-06-22
}}</ref><ref>{{cite news
|last= Olson
|first= Parmy
|url= http://blogs.forbes.com/parmyolson/2011/06/06/lulzsec-hackers-posts-sony-dev-source-code-get-7k-donation/
|title= LulzSec Hackers Post Sony Dev. Source Code, Get $7K Donation – Parmy Olson – Disruptors – Forbes
|publisher= Blogs.forbes.com
|date= 6 June 2011
|accessdate = 2011-06-22
}}</ref>

====Silk Road====
[[Silk Road]] is an anonymous black market that uses only the Bitcoin.<ref name="npr-06-12-11">
{{Cite news
|url= http://www.npr.org/2011/06/12/137138008/silk-road-not-your-fathers-amazon-com
|date= 12 June 2011
|newspaper= NPR
|title= Silk Road: Not Your Father's Amazon.com
|author= Staff
}}</ref>

In a 2011 letter to Attorney General Eric Holder and the Drug Enforcement Administration, senators Charles Schumer of New York and Joe Manchin of West Virginia called for an investigation into Silk Road and the Bitcoin.<ref name="npr-06-12-11"/>
Schumer described the use of Bitcoins at Silk Road as a form of money laundering.<ref name="ars-06-08-11"/>

====Botnet mining====
In June 2011, Symantec warned about the possibility of botnets engaging in covert "mining" of Bitcoins,<ref>{{Cite web|author=Updated: 17 June 2011 | Translations available: 日本語 |url=http://www.symantec.com/connect/blogs/bitcoin-botnet-mining |title=Bitcoin Botnet Mining | Symantec Connect Community |publisher=Symantec.com |date=2011-06-17 |accessdate = 2012-01-24}}</ref><ref>{{Cite web|url=http://www.zdnet.com/blog/security/researchers-find-malware-rigged-with-bitcoin-miner/8934 |title=Researchers find malware rigged with Bitcoin miner |publisher=ZDNet |date=2011-06-29 |accessdate = 2012-01-24}}</ref> consuming computing cycles, using extra electricity and possibly increasing the temperature of the computer. Later that month, the Australian Broadcasting Corporation caught an employee using the company's servers to generate Bitcoins without permission.<ref>{{Cite web|url=http://thenextweb.com/au/2011/06/23/abc-employee-caught-mining-for-bitcoins-on-company-servers/ |title=ABC employee caught mining for Bitcoins on company servers |publisher=The Next Web |date=2011-06-23 |accessdate = 2012-01-24}}</ref> Some malware also uses the parallel processing capabilities of the GPUs built into many modern-day video cards.<ref>{{Cite news |url=http://www.theregister.co.uk/2011/08/16/gpu_bitcoin_brute_forcing/ |title=Malware mints virtual currency using victim's GPU |date=16 August 2011|first=Dan |last=Goodin }}</ref> In mid August 2011, Bitcoin miner botnets were found;<ref>{{Cite web|url=http://www.infosecurity-magazine.com/view/20211/researcher-discovers-distributed-bitcoin-cracking-trojan-malware/ |title=Infosecurity – Researcher discovers distributed bitcoin cracking trojan malware |publisher=Infosecurity-magazine.com |date=2011-08-19 |accessdate = 2012-01-24}}</ref> trojans infecting Mac OS X have also been uncovered.<ref>{{Cite web|url=http://www.techworld.com.au/article/405849/mac_os_x_trojan_steals_processing_power_produce_bitcoins |title=Mac OS X Trojan steals processing power to produce Bitcoins – sophos, security, malware, Intego – Vulnerabilities – Security |publisher=Techworld |date=2011-11-01 |accessdate = 2012-01-24}}</ref>

===Theft and fraud===
On 19 June 2011, a security breach of the Mt.Gox (an acronym for ''M''agic: ''T''he ''G''athering ''O''nline E''x''change, its original purpose) Bitcoin Exchange caused the price of a Bitcoin to briefly drop to US$0.01 on the Mt.Gox exchange (though it remained unaffected on other exchanges) after a hacker allegedly used credentials from a Mt.Gox auditor's compromised computer to illegally transfer a large number of Bitcoins to him- or herself and sell them all, creating a massive "ask" order at any price. Within minutes the price rebounded to over $15 before Mt.Gox shut down their exchange and canceled all trades that happened during the hacking period.<ref>[https://mtgox.com/press_release_20110630.html Clarification of Mt Gox Compromised Accounts and Major Bitcoin Sell-Off]</ref><ref>[http://www.youtube.com/watch?v=T1X6qQt9ONg YouTube. Bitcoin Report]</ref> The exchange rate of Bitcoins quickly returned to near pre-crash values.<ref name="mick">Jason Mick, 19 June 2011, [http://www.dailytech.com/Inside+the+MegaHack+of+Bitcoin+the+Full+Story/article21942.htm Inside the Mega-Hack of Bitcoin: the Full Story], DailyTech</ref><ref>Timothy B. Lee, 19 June 2011, [http://arstechnica.com/tech-policy/news/2011/06/bitcoin-price-plummets-on-compromised-exchange.ars Bitcoin prices plummet on hacked exchange], Ars Technica</ref><ref>Mark Karpeles, 20 June 2011, [https://support.mtgox.com/entries/20208066-huge-bitcoin-sell-off-due-to-a-compromised-account-rollback Huge Bitcoin sell off due to a compromised account – rollback], Mt.Gox Support</ref><ref name="register1">{{Cite news
|title= Bitcoin collapses on malicious trade – Mt Gox scrambling to raise the Titanic
|url= http://www.theregister.co.uk/2011/06/19/bitcoin_values_collapse_again/
|date= 2011-06-19
|author= Chirgwin, Richard
|publisher= The Register
}}</ref> Accounts with the equivalent of more than USD 8,750,000 were affected.<ref name="mick" />

In July 2011, The operator of Bitomat, the third largest Bitcoin exchange, announced that he lost access to his wallet.dat file with about 17,000 BitCoins (roughly equivalent to 220,000 USD at that time). He announced that he would sell the service for the missing amount, aiming to use funds from the sale to refund his customers.<ref>[http://siliconangle.com/blog/2011/08/01/third-largest-bitcoin-exchange-bitomat-lost-their-wallet-over-17000-bitcoins-missing/ Third Largest Bitcoin Exchange Bitomat Lost Their Wallet, Over 17,000 Bitcoins Missing]. SiliconAngle</ref>

In August 2011, MyBitcoin, one of popular Bitcoin transaction processors, declared that it was hacked, which resulted in it being shut down, with paying 49% on customer deposits, leaving more than 78,000 BitCoins (roughly equivalent to 800,000 USD at that time) unaccounted for.<ref>[http://betabeat.com/2011/08/mybitcoin-spokesman-finally-comes-forward-what-did-you-think-we-did-after-the-hack-we-got-shitfaced/ MyBitcoin Spokesman Finally Comes Forward: “What Did You Think We Did After the Hack? We Got Shitfaced”]. BetaBeat</ref><ref>[http://betabeat.com/2011/08/search-for-owners-of-mybitcoin-loses-steam/ Search for Owners of MyBitcoin Loses Steam]. BetaBeat</ref>

In early August 2012, a lawsuit was filed in San Francisco court against Bitcoinica, claiming about 460,000 USD from the company. Bitcoinica was hacked twice in 2012, which led to allegations of neglecting the safety of customers' money and cheating them out of withdrawal requests.<ref>[http://arstechnica.com/tech-policy/2012/08/bitcoinica-users-sue-for-460k-in-lost-bitcoins/ Bitcoinica users sue for $460k in lost Bitcoins]. Arstechnica</ref><ref>[http://spectrum.ieee.org/tech-talk/computing/networks/first-bitcoin-lawsuit-filed-in-san-francisco First Bitcoin Lawsuit Filed In San Francisco]. IEEE Spectrum</ref>

In late August 2012, Bitcoin Savings and Trust was shut down by the owner, allegedly leaving around $5.6 million in debts; this led to allegations of the operation being a Ponzi scheme.<ref>{{Cite web|title=Bitcoin ponzi scheme – investors lose $5 million USD in online hedge fund|url=http://rt.com/usa/news/investors-currency-digital-fund-868/|publisher=RT}}</ref><ref>{{Cite web|last=Jeffries|first=Adrianne|title=Suspected multi-million dollar Bitcoin pyramid scheme shuts down, investors revolt|url=http://www.theverge.com/2012/8/27/3271637/bitcoin-savings-trust-pyramid-scheme-shuts-down|publisher=The Verge}}</ref><ref>{{Cite web|last=Mick|first=Jason|title="Pirateat40" Makes Off $5.6M USD in BitCoins From Pyramid Scheme|url=http://www.dailytech.com/Pirateat40+Makes+Off+56M+USD+in+BitCoins+From+Pyramid+Scheme/article25538.htm|publisher=DailyTech}}</ref><ref>[http://pandodaily.com/2012/08/31/bitcoin-how-a-virtual-currency-became-real-with-a-5-6m-fraud/ Bitcoin: How a Virtual Currency Became Real with a $5.6M Fraud]. PandoDaily</ref> In September 2012, it was reported that U.S. Securities and Exchange Commission has started an investigation on the case.<ref>[http://blogs.telegraph.co.uk/technology/willardfoxton2/100007836/bitcoin-pirate-scandal-sec-steps-in-amid-allegations-that-the-whole-thing-was-a-ponzi-scheme/ Bitcoin 'Pirate' scandal: SEC steps in amid allegations that the whole thing was a Ponzi scheme ]. The Telegraph</ref>

In September 2012, Bitfloor Bitcoin exchange also reported being hacked, with 24,000 BitCoins (roughly equivalent to 250,000 USD) stolen. As a result, Bitfloor suspended operations.<ref>[http://www.bbc.co.uk/news/technology-19486695 Bitcoin theft causes Bitfloor exchange to go offline]. BBC</ref><ref>[http://www.theverge.com/2012/9/5/3293375/bitfloor-bitcoin-exchange-suspended-theft Bitcoin exchange BitFloor suspends operations after $250,000 theft Bitcoin exchange BitFloor suspends operations after $250,000 theft]. The Verge</ref> The same month, Bitfloor resumed operations, with its founder saying that he reported the theft to FBI, and that he is planning to repay the victims, though the time frame for such repayment is unclear.<ref>[http://www.pcworld.com/article/2010586/bitcoin-exchange-back-online-after-hack.html?tk=rel_news Bitcoin exchange back online after hack]. PCWorld</ref>

===Taxation===
In September 2012, the Intra-European Organization of Tax Administrations (IOTA), in Tbilisi, Georgia, held a workshop titled "Auditing Individuals and Legal Entities in the Use of e-Money." The workshop was attended by representatives from 23 countries.<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref> Jerry Taylor, IOTA's technical taxation expert, said, "There's an awful lot happening on the Internet environment which is fascinating at the moment and introducing new challenges for auditors when it comes to virtual currency."<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref> Bitcoin was mentioned during the workshop.<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref>

Matthew Elias, founder of the [[Cryptocurrency Legal Advocacy Group]] (CLAG) published "Staying Between the Lines: A Survey of U.S. Income Taxation and its Ramifications on Cryptocurrencies", which discusses "the taxability of cryptocurrencies such as bitcoin."<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref> CLAG "stressed the importance for taxpayers to determine on their own whether taxes are due on a bitcoin-related transaction based on whether one has "experienced a realization event."<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref> Such examples are "when a taxpayer has provided a service in exchange for bitcoins, a realization event has probably occurred, and any gain or loss would likely be calculated using fair market values for the service provided."<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref>

[[Peter Vessenes]], [[Bitcoin Foundation|Bitcoin Foundation's]] executive director, said, since the foundation is trying to pay for everything in bitcoin, including salaries, "How do we W-2 someone for their bitcoins? Do we mark-to-market every time a transfer happens? Payroll companies cringe."<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref> The Bitcoin Foundation hopes "to push for solid guidance about its legal and tax treatment." [[Patrick Murck]], legal counsel for the Bitcoin Foundation, said he would like "to help regulators understand the technology better so they can make better decisions."<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref> Murck said, "Bitcoin has the potential to become much more than a niche currency, but it needs the guidance and understanding of regulators." and "The full potential of bitcoin could be realized through clearer guidelines and a better understanding by financial and tax regulators." and "Part of making that happen is to talk to regulators, the IRS, and tax professionals and helping them understand that bitcoin is not this nefarious thing, it's just software, it's a community, and there's nothing inherently nefarious about either of those things."<ref name="BitCoin Tax issues Oct 2012">{{cite journal | title=2012 TNT 209-4 NEWS ANALYSIS: VIRTUAL CURRENCY: A NEW WORRY FOR TAX ADMINISTRATORS?. (Release Date: OCTOBER 17, 2012) (Doc 2012-21516) | author=Stewart, David D. and Soong Johnston, Stephanie D. | journal=Tax Notes Today | year=2012 | month=October 29 | volume=2012 TNT 209-4 | issue=2012 TNT 209-4}}</ref>

==See Also==
* [[Introduction]]
* [[Getting started]]
* [[Using_Bitcoin|Detailed tutorial]]
* [[FAQ]]

==References==
<references />

[[Category:Digital currencies]]

Talk:Scalability

2013-03-29T23:09:39Z

Alvox: /* satoshiDICE */ new section

== Response to Dan Kaminskys presentation ==

[http://www.slideshare.net/dakami/bitcoin-8776098 Dans slides] were presented at Blackhat 2011.

=== Response from Mike Hearn (original author) ===

Mike responded [https://bitcointalk.org/index.php?topic=34597.0 in this forum thread].

=== Response from Gregory Maxwell ===

When techies hear about how bitcoin works they frequently stop at the word "flooding" and say "Oh-my-god! that can't scale!". The purpose of this article is to take an extreme example, the peak transaction rate of Visa, and show that bitcoin ''could'' technically reach that kind of rate without any kind of questionable reasoning, changes in the core design, or non-existent overlays. As such, it's merely an extreme example— not a plan for how bitcoin will grow to address wider needs (as a decentralized system it is the bitcoin using public who will decide how bitcoin grows)— it's just an argument that shows that bitcoin's core design can scale much better than an intelligent person might guess at first.

Dan rightly criticizes the analysis presented here— pointing out that operating at this scale would significantly reduce the decentralized nature of bitcoin: If you have to have many terabytes of disk space to run a "full validating" node then fewer people will do it, and everyone who doesn't will have to trust the ones who do to be honest. Dan appears (from his slides) to have gone too far with that argument: he seems to suggest that this means bitcoins will be controlled by the kind of central banks that are common today. His analysis fails for two reasons (and the second is the fault of this page being a bit misleading):

First, even at the astronomic scale presented here the required capacity is well within the realm of (wealthy) private individuals, and certainly would be at some future time when that kind of capacity was required. A system which puts private individuals, or at least small groups of private parties, on equal footing with central banks could hardly be called a centralized one, though it would be less decentralized than the bitcoin we have today. The system could also not get to this kind of scale without bitcoin users agreeing collectively to increase the maximum block size, so it's not an outcome that can happen without the consent of bitcoin users.

Second, and most importantly, the assumed scaling described here deals with Bitcoin replacing visa. This is a poor comparison because bitcoin alone is not a perfect replacement for visa for reasons completely unrelated to scaling: Bitcoin does not offer instant transactions, credit, or various anti-fraud mechanisms (which some people want, even if not everyone does), for example. Bitcoin is a more complete replacement for checks, wire transfers, money orders, gold coins, CDs, savings accounts, etc. and if widely adopted probably replace the uses of credit cards which would be better served by these other things if they worked better online.

Bitcoin users sometimes gloss over this fact too quickly because people are too quick to call it a flaw but this is unfair. No one system is ideal for all usage and Bitcoin has a broader spectrum of qualities than most monetary instruments. If the bitcoin community isn't willing to point out some things would better be done by other systems then it becomes easy to make strawman arguments: If we admit that bitcoin could be used as a floor wax and desert topping, someone will always point out that it's not the best floorwax or best desert topping.

It's trivial to build payment processing and credit systems _on top_ of bitcoin, both classic ones (like Visa itself!) as well as decentralized ones like [http://ripple-project.org/ Ripple]. These systems could handle higher transaction volumes with lower costs, and settle frequently to the bitcoin that backs them. These could use other techniques with different tradeoffs than bitcoin, but still be backed and denominated by bitcoin so still enjoy its lack of central control. We see the beginnings of this today with bitcoin exchange and wallet services allowing instant payments between members.

These services would gain the benefit of the stable inflation resistant bitcoin currency, users would gain the benefits of instant transactions, credit, and anti-fraud, bitcoin overall would enjoy improved scaling from offloaded transaction volume without compromising its decentralized nature. In a world where bitcoin was widely used payment processing systems would probably have lower prices because they would need to compete with raw-bitcoin transactions, they also could be afford lower price because frequent bitcoin settling (and zero trust bitcoin escrow transactions) would reduce their risk. This is doubly true because bitcoin could conceivably scale to replace them entirely, even if that wouldn't be the best idea due to the resulting reduction in decentralization.

== Other discussion ==

There is one major point that the page overlooks: the limitation on block
creation.

Block creation is limited to an average of one block every ten minutes.
Furthermore, block size (which includes the transactions in the block) is limited to 1,000,000 bytes.

Each transaction requires 10 bytes, plus approximately 106 bytes for every
input and approximately 69 bytes for every output. The exact size depends
on the size of the public key, which I have not been able to confirm, but
the keys in my wallet.dat seem to be about 65 bytes each.

If we assume that transactions average two inputs and two outputs, then
the average transaction size will be about 350 bytes ''(note that the main page assumes an average of 1KB per transaction)''. If we further assume
that the block size will, in practice, be limited to 500,000 bytes because
the transaction fees increase as the block size increases, then that means
there will be, on average, approximately 1430 transactions per block. That
works out to an average of 2.5 transactions per second - '''well''' below
the stated goal of at least 4,000 transactions per second.

Even if we assume only one input and one output per transaction, and that
each block will contain the full 1,000,000 bytes, that still works out to only 5,405
transactions per block, or 9 transactions per second.

Unfortunately, this is '''not''' a limitation that can be overcome by
simply increasing memory, or switching to a different ISP with more
bandwidth. It is a built-in limitation, designed to '''deliberately'''
slow down block creation. One solution is to somehow allow blocks to be freely created, while still keeping the rate of coin creation constant.

The bottom line is that, ''as it sits'', this system is not scalable.
:MAX_BLOCK_SIZE has always been planned to increase as needed. That limitation should be ignored. [[User:Theymos|theymos]] 17:15, 4 March 2011 (GMT)
:What Theymos said. Increasing MAX_BLOCK_SIZE will be done when "lightweight, header-only" client mode is done. Until then, block size has to be kept under control.--[[User:Gavinandresen|Gavin Andresen]] 00:19, 5 March 2011 (GMT)
:I've updated the page with more discussion of this topic. --[[User:Mike|Mike]] March 5 2011

The thing with VISA or and credit card company is that there wouldn't be that many actual transactions. When I buy stuff with my credit card the vender doesn't get paid instantly. I pay my bill once a month and the vender gets all his transactions lumped into one payment from VISA (once a week, I think). Someone correct me if I'm wrong, but the number of real transfers of money would be much smaller. --[[User:Randomproof|Randomproof]] 17:29, 1 April 2011 (GMT)

Would also be nice to get some kind of an estimate on how much the crypto-operations could be accelerated with a GPU.
[[User:Jojkaart|Jojkaart]] 20:48, 13 June 2011 (GMT)

Shouldn't this (under Opimizations -> Network Structure): "''Switching to DNS would give dramatically faster startup times that do not scale with the size of the network.''" read: "''Switching to DNS would give dramatically faster startup times that do scale with the size of the network.''"? ie Remove the "not".
--[[User:Tokoin|Tokoin]] 09:24, 21 July 2011 (GMT)

== Moore's law ==

I think Moore's law should be mentioned.

Even though now the comparison to Visa produces requirements for processing power, data storage or network capacity appear overwhelming for a casual user, the cost/performance ratio decreases all the time. My calculations based on data from wikipedia projected for 2020:

=== Disk space ===

Wikipedia quotes a research article that estimates that "in 2020 a two-platter, 2.5-inch disk drive will be capable of storing more than 14 terabytes(TB) and will cost about $40". This can hold about 85 days of data (~3 months) at "visa-speed". This is a bit pricey, but within the scope of a normal user, and definitely enough for enthusiasts.

=== Network capacity ===

Wikipedia references articles that estimate the "moore's law" equivalent for network to be 50% increase / year. For 9 years (2011-2020), this makes an increase of approximately 38 times. In order to achieve the speed of 1GB/s, this is the equivalent of someone having 27MB/s at the moment, i.e. 215Mbit/s. I think this exceeds a normal user and most enthusiasts. Assuming a casual user has 2Mbit/s at the moment, he'll scale to "visa-speed" in about 16 years, i.e. 2027.

=== CPU performance ===

Moore's law is approximated as "doubling every 18 months". For 9 years this makes 34 times if I'm calculating right. 50/34 = 1.47 cores. A dual-core computer in 2020 should therefore be sufficient to handle relaying/verifying Bitcoin transactions at visa-speed. I'm ignoring mining. So why someone is proposing that double tx check should be removed from the protocol ? We would surely leave the door open to some nasty attacks if strange transactions or double spends slip into blocks from attacking miners.

=== Summary ===

I only made very rough estimates. Feel free to recalculate with more accurate data. My conclusion is that CPU would be a no-brainer, disk space would be an annoyance, however network speed would indeed appear to be a problem.

== satoshiDICE ==

I believe the implications of [[SatoshiDice]] and similar schemes that stress the network should be mentioned, since as of March 2013, SatoshiDice transactions occupy 80% of the [[block chain]]. -- [[User:Alvox|Alvox]] ([[User talk:Alvox|talk]]) 23:09, 29 March 2013 (GMT)

Myths

2013-03-29T22:55:29Z

Alvox: /* Bitcoin was hacked */ Create References section

Let's clear up some common Bitcoin misconceptions.

== Bitcoin is just like all other digital currencies; nothing new ==

Nearly all other digital currencies are centrally controlled. This means that:
* They can be printed at the subjective whims of the controllers
* They can be destroyed by attacking the central point of control
* Arbitrary rules can be imposed upon their users by the controllers

Being decentralized, Bitcoin solves all of these problems.

== Bitcoins don't solve any problems that fiat currency and/or gold doesn't solve ==

Unlike gold, bitcoins are:
* Easy to transfer
* Easy to secure
* Easy to verify
* Easy to granulate

Unlike fiat currencies, bitcoins are:
* Predictable and limited in [[Controlled_Currency_Supply|supply]]
* Not controlled by a central authority (such as [http://en.wikipedia.org/wiki/Federal_Reserve The United States Federal Reserve])
* Not debt-based

Unlike electronic fiat currency systems, bitcoins are:
* Potentially anonymous
* Freeze-proof
* Faster to transfer
* Cheaper to transfer

== Bitcoin is backed by processing power ==

It is not correct to say that Bitcoin is "backed by" processing power. A currency being "backed" means that it is pegged to something else via a central party at a certain exchange rate yet you cannot exchange bitcoins for the computing power that was used to create them. Bitcoin is in this sense not backed by anything. It is a currency in its own right. Just as gold is not backed by anything, the same applies to Bitcoin.

The Bitcoin currency is ''created'' via processing power, and the integrity of the block chain is ''protected'' by the existence of a network of powerful computing nodes from certain [[Weaknesses#Attacker_has_a_lot_of_computing_power|attacks]].

== Bitcoins are worthless because they aren't backed by anything ==

One could argue that gold isn't backed by anything either. Bitcoins have properties resulting from the system's design that allows them to be subjectively valued by individuals. This valuation is demonstrated when individuals freely exchange for or with bitcoins. Please refer to the [http://en.wikipedia.org/wiki/Subjective_theory_of_value Subjective Theory of Value].

See also: the "[[#Bitcoin_is_backed_by_processing_power|Bitcoin is backed by processing power]]" myth.

== The value of bitcoins are based on how much electricity and computing power it takes to mine them ==

This statement is an attempt to apply to Bitcoin the [http://en.wikipedia.org/wiki/Labor_theory_of_value labor theory of value], which is generally accepted as false. Just because something takes X resources to create does not mean that the resulting product will be worth X. It can be worth more, or less, depending on the utility thereof to its users.

In fact the causality is the reverse of that (this applies to the labor theory of value in general). The cost to mine bitcoins is based on how much they are worth. If bitcoins go up in value, more people will mine (because [[Mining|mining]] is profitable), thus [[difficulty]] will go up, thus the cost of mining will go up. The inverse happens if bitcoins go down in value. These effects balance out to cause mining to always cost an amount proportional to the value of bitcoins it produces.

== Bitcoins have no intrinsic value (unlike some other things) ==

It is true that bitcoins have no intrinsic value, in the [http://en.wikipedia.org/wiki/Intrinsic_value_%28numismatics%29 numismatic sense], in other words, value in any realm outside of being used as a medium of exchange.

However, while some tangible commodities do have intrinsic value, that value is generally much less than its trading price. Consider for example that gold, if it were not used as an inflation-proof store of value, but rather only for its industrial uses, would certainly not be worth what it is today, since the industrial requirements for gold are far smaller than the available supply thereof.

While historically intrinsic value, as well as other attributes like divisibility, fungibility, scarcity, durability, helped establish certain commodities as mediums of exchange, it is certainly not a prerequisite. While bitcoins lack 'intrinsic value' in this sense, they make up for it in spades by possessing the other qualities necessary to make it a good medium of exchange, equal to or better than [http://en.wikipedia.org/wiki/Commodity_money commodity money].

Value is ultimately determined by what people are willing to trade for - by supply and demand.

== Bitcoins are illegal because they're not legal tender ==
In March 2013, the U.S. [http://en.wikipedia.org/wiki/Financial_Crimes_Enforcement_Network Financial Crimes Enforcement Network] issues a new set of guidelines on "de-centralized virtual currency", clearly targeting Bitcoin. Under the new guidelines, "a user of virtual currency is not a Money Services Businesses (MSB) under FinCEN's regulations and therefore is not subject to MSB registration, reporting, and record keeping regulations." [[Mining|Miners]] on the other hand, might need to register, if they sell bitcoins for "real currency or its equivalent".<ref>[http://arstechnica.com/tech-policy/2013/03/us-regulator-bitcoin-exchanges-must-comply-with-money-laundering-laws/ US regulator: Bitcoin exchanges must comply with money-laundering laws | Ars Technica]</ref>

In general, there are a [http://en.wikipedia.org/wiki/Local_currency number of currencies] in existence that are not official government-backed currencies. A currency is, after all, nothing more than a convenient unit of account. While national laws may vary from country to country, and you should certainly check the laws of your jurisdiction, in general trading in any commodity, including digital currency like Bitcoin, [http://en.wikipedia.org/wiki/BerkShares BerkShares], game currencies like WoW gold, or Linden dollars, is not illegal.

== Bitcoin is a form of domestic terrorism because it only harms the economic stability of the USA and its currency ==

According to [http://en.wikipedia.org/wiki/Definitions_of_terrorism#United_States the definition of terrorism in the United States], you need to do violent activities to be considered a terrorist for legal purposes. Recent off-the-cuff remarks by politicians have no basis in law or fact.

Also, Bitcoin isn't domestic to the US or any other country. It's a worldwide community, as can be seen in this [https://bitcointalk.org/?topic=2346.0 map of Bitcoin nodes].

== Bitcoin will only enable tax evaders which will lead to the eventual downfall of civilization ==

Cash transactions hold the same level of anonymity but are still taxed successfully. It is up to you to follow the applicable state laws in your home country, or face the consequences.

While it may be easy to transfer bitcoins anonymously, ''spending'' them anonymously on tangibles is just as hard as spending any other kind of money anonymously. Tax evaders are often caught because their lifestyle and assets are inconsistent with their reported income, and not necessarily because government is able to follow their money.

== Bitcoins can be printed/minted by anyone and are therefore worthless ==

Bitcoins are not printed/minted. Instead, [[Blocks]] are computed by miners and for their efforts they are awarded a specific amount of bitcoins and transaction fees paid by others. See [[Mining]] for more information on how this process works.

== Bitcoins are worthless because they're based on unproven cryptography ==

SHA256 and ECDSA which are used in Bitcoin are well-known industry standard algorithms. SHA256 is endorsed and used by the US Government and is standardized (FIPS180-3 Secure Hash Standard). If you believe that these algorithms are untrustworthy then you should not trust Bitcoin, credit card transactions or any type of electronic bank transfer. Bitcoin has a sound basis in well understood cryptography.

== Early adopters are unfairly rewarded ==

Early adopters are rewarded for taking the higher risk with their time and money. This argument is akin to saying that people who buy stock at a company IPO (Initial Public Offering) are unfairly rewarded. This argument also depends on bitcoin early adopters using bitcoins to store rather than transfer value. The daily trade on the exchanges (as of Jan 2012) indicates that smaller transactions are becoming the norm, indicating trade rather than investment.

In more pragmatic terms, "fairness" is an arbitrary concept that is improbable to be agreed upon by a large population. Establishing "fairness" is no goal of Bitcoin, as this would be impossible.

By starting to mine or acquire bitcoins today, you too can become an early adopter.

== 21 million coins isn't enough; doesn't scale ==

One Bitcoin is divisible down to eight decimal places. There are really 2,099,999,997,690,000 (just over 2 quadrillion) maximum possible atomic units in the bitcoin design.

The value of "1 BTC" represents 100,000,000 of these. In other words, each is divisible by up to 10^8.

As the value of the unit of 1 BTC grows too large to be useful for day to day transactions, people can start dealing in smaller [[Units|units]], such as milli-bitcoins (mBTC) or micro-bitcoins (μBTC).

== Bitcoins are stored in wallet files, just copy the wallet file to get more coins! ==

No, your wallet contains your secret keys, giving you the rights to spend your bitcoins. Think of it like having bank details stored in a file. If you give your bank details (or bitcoin wallet) to someone else, that doesn't double the amount of money in your account. You can spend your money or they can spend your money, but not both.

== Lost coins can't be replaced and this is bad ==

Bitcoins are divisible to 0.00000001, so there being fewer bitcoins remaining is not a problem for the currency itself. If you lose your coins, all other coins will go up in value a little. Consider it a donation to all other bitcoin users.

A related question is: Why don't we have a mechanism to replace lost coins? The answer is that it is impossible to distinguish between a 'lost' coin and one that is simply sitting unused in someone's wallet.

== It's a giant 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. In a ponzi scheme, early adopters can only profit at the expense of late adopters, and the late adopters always lose. Bitcoin has an expected win-win outcome. Early and present adopters profit from the rise in value as Bitcoins become better understood and in turn demanded by the public at large. All adopters benefit from the usefulness of a reliable and widely-accepted decentralized peer-to-peer currency.

== Finite coins plus lost coins means deflationary spiral ==
As deflationary forces may apply, economic factors such as hoarding are offset by human factors that may lessen the chances that a [[Deflationary spiral]] will occur.

== Bitcoin can't work because there is no way to control inflation ==

Inflation is simply a rise of prices over time, which is generally the result of the devaluing of a currency. This is a function of supply and demand. Given the fact that the supply of bitcoins is fixed at a certain amount, unlike fiat money, the only way for inflation to get out of control is for demand to disappear. Temporary inflation is possible with a rapid adoption of Fractional Reserve Banking but will stabilize once a substantial number of the 21 million "hard" bitcoins are stored as reserves by banks.

Given the fact that Bitcoin is a distributed system of currency, if demand were to decrease to almost nothing, the currency would be doomed anyway.

The key point here is that Bitcoin as a currency can't be inflated by any single person or entity, like a government, as there's no way to increase supply past a certain amount.

Indeed, the most likely scenario, as Bitcoin becomes more popular and demand increases, is for the currency to increase in value, or deflate, until demand stabilizes.

== The Bitcoin community consists of anarchist/conspiracy theorist/gold standard 'weenies' ==

The members of the community vary in their ideological stances.

== Anyone with enough computing power can take over the network ==

CONFIRMED, see [[Weaknesses]].

That said, as the network grows, it becomes harder and harder for a single entity to do so. Already the Bitcoin network's computing power is quite ahead of the world's fastest supercomputers, together.

What an attacker can do once the network is taken over is quite limited. Under no circumstances could an attacker create counterfeit coins, fake transactions, or take anybody else's money. An attacker's capabilities are limited to taking back their own money that they very recently spent, and preventing other people's transactions from receiving confirmations. Such an attack would be very costly in resources, and for such meager benefits there is little rational economic incentive to do such a thing.

Furthermore, this attack scenario would only be feasible for as long as it was actively underway. As soon as the attack stopped, the network would resume normal operation.

== Bitcoin violates governmental regulations ==

There is no known governmental regulation which disallows the use of Bitcoin.

See also: the "[[#Bitcoins_are_illegal_because_they.27re_not_legal_tender|Bitcoins are illegal because they're not legal tender]]" myth.

== Fractional reserve banking is not possible ==

It is possible. See the main article, [[Fractional Reserve Banking and Bitcoin]]

== Point of sale with bitcoins isn't possible because of the 10 minute wait for confirmation ==

It is true that transactions [[FAQ#Why_do_I_have_to_wait_10_minutes_before_I_can_spend_money_I_received.3F|can]] sometimes take tens of minutes to become ''confirmed''. Despite this, retailers can accept unconfirmed transactions with very little risk by simply 'listening' on the network for a double-spend transaction, or partnering with a company that provides this service. After a head start of merely several seconds, the original transaction would reach so much of the Bitcoin network that a fraudulent double-spend transaction would almost certainly be fruitless. An attacker would have to commit easily-detectable fraud, in person, several hundred or several thousand times, before one of these low-value double-spend attempts would likely succeed.

An attacker could work around the necessity of sending out a second fraudulent transaction to the Bitcoin network by attempting to [[Mining|solo-mine]] an attack block containing the attack transaction himself - temporarily withholding the block with the rest of the network - and then execute the fraudulent purchase within seconds, or minutes at most, of mining the attack block, before broadcasting the attack block. However, the cost of such an activity would dramatically outweigh the value of anything typically offered without a confirmation wait for several reasons.

First, mining a block (attack or otherwise) entitles the miner to a valuable block reward, and because the attack involves temporarily withholding the block from the network, the attacker would put himself in the likely position of his block becoming [[Stale block|stale]], which would result in forfeiture of the entire reward. Most solo miners solve less than one block per month, so this would represent the loss of proceeds of potentially several weeks of mining.

Second, it is not possible for a solo miner to know exactly when his mining activity will yield a block, and because the attack must be carried out within seconds or minutes of successfully mining a block, the attacker will not be able to know or plan in advance the brief window when the attack would be likely to succeed. While it may be easy for a determined attacker to get low-value items that are sold and delivered online instantly without waiting for confirmations (such as downloads), this unpredictability and the briefness of the opportunity would make it extremely difficult to commit any kind of fraud where real-life interaction is required, such as visiting a merchant or taking possession of goods. Petty shoplifting would be far simpler. Even if an attacker went forward with this attack, the retailer would be notified of the fraud the moment the attack block is released seconds later.

In short, the 10-minute wait for confirmation is only practically necessary when delivering goods of value that significantly exceed the block reward an attacker would have to risk to perform an attack and where recourse after delivery is practically nonexistent, such as money transfers.

== After 21 million coins are mined, no one will generate new blocks ==

When operating costs can't be covered by the block creation bounty, which will happen some time before the total amount of BTC is reached, miners will earn some profit from [[transaction fees]]. However unlike the block reward, there is [http://bitcoin.stackexchange.com/questions/876/how-much-will-transaction-fees-eventually-be/895#895 no coupling between transaction fees and the need for security], so there is less of a guarantee that the amount of [[Mining|mining]] being performed will be sufficient to maintain the network's security.

== Bitcoin has no built-in chargeback mechanism, and this isn't good ==

'''Why some people think this is bad''': Chargebacks are useful for limiting fraud. The person handling your money has a responsibility to prevent fraud. If you buy something on eBay and the seller never ships it, PayPal takes funds from the seller's account and gives you back the money. This strengthens the eBay economy, because people recognize that their risk is limited and are more willing to purchase items from risky sellers.

'''Why it's actually a good thing''': Bitcoin is designed such that your money is yours and yours alone. Allowing chargebacks implies that it is possible for another entity to take your money from you. You can have either total ownership rights of your money, or fraud protection, but not both. That said, nothing inherent in the dollar or euro or any other currency is necessary for chargebacks to be possible, and likewise, nothing prevents the creation of PayPal-like services denominated in Bitcoin that provide chargebacks or fraud protection.

The statement "The person handling your money has a responsibility to prevent fraud" is still true; the power has been shifted into your own hands. Fraud will always exist. It's up to you to only send bitcoins to trusted entities. It is possible to trust an online identity without ever knowing their physical identity; see the [http://wiki.bitcoin-otc.com/wiki/OTC_Rating_System OTC Web of Trust].

== Quantum computers would break Bitcoin's security ==

While ECDSA is indeed not secure under quantum computing, quantum computers don't yet exist and probably won't for a while.
The DWAVE system often written about in the press is, even if all their claims are true, not a quantum computer of a kind that could be used for cryptography.
Bitcoin's security, when used properly with a new address on each transaction, depends on more than just ECDSA: Cryptographic hashes are much stronger than ECDSA under QC.
Bitcoin's security was designed to be upgraded in a forward compatible way and could be [http://en.wikipedia.org/wiki/Post-quantum_cryptography upgraded] if this were considered an imminent threat.

See the implications of quantum computers on public key cryptography here http://en.wikipedia.org/wiki/Quantum_computer#Potential

The ''risk'' of quantum computers is also there for financial institutions, like banks, because they heavily rely on cryptography when doing transactions.

== [[Mining|Bitcoin mining]] is a waste of energy and harmful for ecology ==

No more so than the wastefulness of mining gold out of the ground, melting it down and shaping it into bars, and then putting it back underground again. Not to mention the building of big fancy buildings, the waste of energy printing and minting all the various fiat currencies, the transportation thereof in armored cars by no less than two security guards for each who could probably be doing something more productive, etc.

As far as mediums of exchange go, Bitcoin is actually quite economical of resources, compared to others.

'''Economic Argument 1'''

[[Mining|Bitcoin mining]] is a highly competitive, dynamic, almost [http://en.wikipedia.org/wiki/Perfect_market perfect], market. Mining rigs can be set up and dismantled almost anywhere in the world with relative ease. Thus, market forces are constantly pushing mining activity to ''places'' and ''times'' where the marginal price of electricity is low or zero. These electricity products are cheap for a reason. Often it’s because the electricity is difficult (and wasteful) to transport, difficult to store, or because there is low demand and high supply. Using electricity in this way is a lot less wasteful than simply plugging a mining rig into the mains indiscriminately.

For example, Iceland produces an excess of cheap electricity from renewable sources, but it has no way of exporting electricity because of its remote location. It is conceivable that at some point in future Bitcoin mining will only be profitable in places like Iceland, and unprofitable in places like central Europe, where electricity comes mostly from nuclear and fossil sources.

Market forces could even push mining into innovative solutions that have an effective electricity consumption of ''zero''. Mining always produces heat equivalent to the energy consumed - for example, 1000 watts of mining equipment produces the same amount of heat as a 1000 watt heating element used in an electric space heater, hot tub, water heater, or similar appliance. Someone already in a willing position to incur the cost of electricity for its heat value alone could run mining equipment specially designed to mine bitcoins while capturing and utilizing the heat produced, without incurring any energy costs beyond what they already intended to spend on heating.

'''Economic Argument 2'''

When the environmental costs of mining are considered, they need to be weighed up against the benefits. If you question Bitcoin on the grounds that it consumes electricity, then you should also ask questions like this: Will Bitcoin promote economic growth by freeing up trade? Will this speed up the rate of technological innovation? Will this lead to faster development of green technologies? Will Bitcoin enable new, border crossing [http://en.wikipedia.org/wiki/Smart_grid smart grid] technologies? …

Dismissal of Bitcoin because of its costs, while ignoring its benefits, is a dishonest argument. In fact, any environmental argument of this type is dishonest, not just pertaining to Bitcoin. Along similar lines, it could be argued that wind turbines are bad for the environment because making the steel structure consumes energy.

== Shopkeepers can't seriously set prices in bitcoins because of the volatile exchange rate ==

Your assumption is that bitcoins must be sold immediately to cover operating expenses. If the shopkeeper's back-end expenses were transacted in bitcoins as well, then the exchange rate would be irrelevant. Larger adoption of Bitcoin would make prices [http://en.wikipedia.org/wiki/Sticky_%28economics%29 sticky]. Future volatility is expected to decrease, as the size and depth of the market grows.

In the meantime, many merchants simply regularly pull the latest market rates from the exchanges and automatically update the prices on their websites. Also you might be able to buy a put option in order to sell at a fixed rate for a given amount of time. This would protect you from drops in price and simplify your operations for that time period.

== Like Flooz and e-gold, bitcoins serve as opportunities for criminals and will be shut down ==

* Visa, MasterCard, PayPal, and cash all serve as opportunities for criminals as well, but society keeps them around due to their recognized net benefit.
* Hopefully Bitcoin will grow to the point where no single organization can disrupt the network, or would be better served by helping it.
* Terrorists fly aircraft into buildings, but the governments have not yet abolished consumer air travel. Obviously the public good outweighs the possible bad in their opinion.
* Criminal law differs between jurisdictions.

== Bitcoins will be shut down by the government just like Liberty Dollars were ==

Liberty Dollars started as a commercial venture to establish an alternative US currency, including physical banknotes and coins, backed by precious metals. This, in and of itself, is not illegal. They were prosecuted under counterfeiting laws because the silver coins allegedly resembled US currency.

Bitcoins do not resemble the currency of the US or of any other nation in any way, shape, or form. The word "dollar" is not attached to them in any way. The "$" symbol is not used in any way.

Bitcoins have no representational similarity whatsoever to US dollars.

Of course, actually 'shutting down' Liberty Dollars was as easy as arresting the head of the company and seizing the offices and the precious metals used as backing. The decentralized Bitcoin, with no leader, no servers, no office, and no tangible asset backing, does not have the same vulnerability.

== Bitcoin is not decentralized because the developers can dictate the software's behavior ==

The Bitcoin protocol was originally defined by Bitcoin's inventor, [[Satoshi Nakamoto]], and this protocol has now been widely accepted as the standard by the community of miners and users.

Though the developers of the original Bitcoin client still exert influence over the Bitcoin community, their power to arbitrarily modify the protocol is very limited. Since the release of Bitcoin v0.3, changes to the protocol have been minor and always in agreement with community consensus.

Protocol modifications, such as increasing the block award from 25 to 50 BTC, are not compatible with clients already running in the network. If the developers were to release a new client that the majority of miners perceives as corrupt, or in violation of the project’s aims, that client would simply not catch on, and the few users who do try to use it would find that their transactions get rejected by the network.

There are also other [[:Category:Clients|Bitcoin clients made by other developers]] that adhere to the Bitcoin protocol. As more developers create alternative clients, less power will lie with the developers of the original Bitcoin client.

== Bitcoin is a pyramid scheme ==

Bitcoin is nearly opposite of a pyramid scheme in a mathematical sense. Because Bitcoins are algorithmically made scarce, no exponential benefit is derived from introducing new users to use of it. There is a quantitative benefit in having additional interest or demand, but this is in no way exponential.

== Bitcoin was hacked ==

In the history of Bitcoin, there has never been an attack on the [[block chain]] that resulted in stolen money from a confirmed output. Neither has there ever been a reported theft resulting directly from a vulnerability in the [[Original Bitcoin client|original Bitcoin client]], or a vulnerability in the protocol. Bitcoin is secured by standard cryptographic functions. These functions have been peer reviewed by cryptography experts and are considered unlikely to be breakable in the foreseeable future.

It is safe to say that the currency itself has never been 'hacked'. However, several major ''websites'' using the currency have been hacked, often resulting in high profile Bitcoin heists. These heists are misreported in some media as hacks on Bitcoin itself. An analogy: Just because someone stole US dollars from a supermarket till, doesn’t mean that the US dollar as a currency has been 'hacked'.

Most bitcoin thefts are the result of inadequate [[Securing your wallet|wallet security]]. In response to the wave of thefts in 2011 and 2012, the community has developed risk-mitigating measures such as [[Wallet_encryption|wallet encryption]], support for [[BIP_0011|multiple signatures]], [[How_to_set_up_a_secure_offline_savings_wallet|offline wallets]], [[Paper_wallet|paper wallets]], and [[Hardware_wallet|hardware wallets]]. As these measures gain adoption by merchants and users, it is expected that the number of thefts will drop.

==References==
<references/>

[[de:Mythen]]

Myths

2013-03-29T22:43:18Z

Alvox: /* Bitcoins are illegal because they're not legal tender */ add FinCEN guidelines

Myths

2013-03-29T22:32:05Z

Alvox: /* Bitcoin is a form of domestic terrorism because it only harms the economic stability of the USA and its currency */ properlinks

Let's clear up some common Bitcoin misconceptions.

== Bitcoin is just like all other digital currencies; nothing new ==

Nearly all other digital currencies are centrally controlled. This means that:
* They can be printed at the subjective whims of the controllers
* They can be destroyed by attacking the central point of control
* Arbitrary rules can be imposed upon their users by the controllers

Being decentralized, Bitcoin solves all of these problems.

== Bitcoins don't solve any problems that fiat currency and/or gold doesn't solve ==

Unlike gold, bitcoins are:
* Easy to transfer
* Easy to secure
* Easy to verify
* Easy to granulate

Unlike fiat currencies, bitcoins are:
* Predictable and limited in [[Controlled_Currency_Supply|supply]]
* Not controlled by a central authority (such as [http://en.wikipedia.org/wiki/Federal_Reserve The United States Federal Reserve])
* Not debt-based

Unlike electronic fiat currency systems, bitcoins are:
* Potentially anonymous
* Freeze-proof
* Faster to transfer
* Cheaper to transfer

== Bitcoin is backed by processing power ==

It is not correct to say that Bitcoin is "backed by" processing power. A currency being "backed" means that it is pegged to something else via a central party at a certain exchange rate yet you cannot exchange bitcoins for the computing power that was used to create them. Bitcoin is in this sense not backed by anything. It is a currency in its own right. Just as gold is not backed by anything, the same applies to Bitcoin.

The Bitcoin currency is ''created'' via processing power, and the integrity of the block chain is ''protected'' by the existence of a network of powerful computing nodes from certain [[Weaknesses#Attacker_has_a_lot_of_computing_power|attacks]].

== Bitcoins are worthless because they aren't backed by anything ==

One could argue that gold isn't backed by anything either. Bitcoins have properties resulting from the system's design that allows them to be subjectively valued by individuals. This valuation is demonstrated when individuals freely exchange for or with bitcoins. Please refer to the [http://en.wikipedia.org/wiki/Subjective_theory_of_value Subjective Theory of Value].

See also: the "[[#Bitcoin_is_backed_by_processing_power|Bitcoin is backed by processing power]]" myth.

== The value of bitcoins are based on how much electricity and computing power it takes to mine them ==

This statement is an attempt to apply to Bitcoin the [http://en.wikipedia.org/wiki/Labor_theory_of_value labor theory of value], which is generally accepted as false. Just because something takes X resources to create does not mean that the resulting product will be worth X. It can be worth more, or less, depending on the utility thereof to its users.

In fact the causality is the reverse of that (this applies to the labor theory of value in general). The cost to mine bitcoins is based on how much they are worth. If bitcoins go up in value, more people will mine (because [[Mining|mining]] is profitable), thus [[difficulty]] will go up, thus the cost of mining will go up. The inverse happens if bitcoins go down in value. These effects balance out to cause mining to always cost an amount proportional to the value of bitcoins it produces.

== Bitcoins have no intrinsic value (unlike some other things) ==

It is true that bitcoins have no intrinsic value, in the [http://en.wikipedia.org/wiki/Intrinsic_value_%28numismatics%29 numismatic sense], in other words, value in any realm outside of being used as a medium of exchange.

However, while some tangible commodities do have intrinsic value, that value is generally much less than its trading price. Consider for example that gold, if it were not used as an inflation-proof store of value, but rather only for its industrial uses, would certainly not be worth what it is today, since the industrial requirements for gold are far smaller than the available supply thereof.

While historically intrinsic value, as well as other attributes like divisibility, fungibility, scarcity, durability, helped establish certain commodities as mediums of exchange, it is certainly not a prerequisite. While bitcoins lack 'intrinsic value' in this sense, they make up for it in spades by possessing the other qualities necessary to make it a good medium of exchange, equal to or better than [http://en.wikipedia.org/wiki/Commodity_money commodity money].

Value is ultimately determined by what people are willing to trade for - by supply and demand.

== Bitcoins are illegal because they're not legal tender ==

Chickens aren't legal tender either, but bartering with chickens is not illegal.

There are a [http://en.wikipedia.org/wiki/Local_currency number of currencies] in existence that are not official government-backed currencies. A currency is, after all, nothing more than a convenient unit of account. While national laws may vary from country to country, and you should certainly check the laws of your jurisdiction, in general trading in any commodity, including digital currency like Bitcoin, [http://en.wikipedia.org/wiki/BerkShares BerkShares], game currencies like WoW gold, or Linden dollars, is not illegal.

== Bitcoin is a form of domestic terrorism because it only harms the economic stability of the USA and its currency ==

According to [http://en.wikipedia.org/wiki/Definitions_of_terrorism#United_States the definition of terrorism in the United States], you need to do violent activities to be considered a terrorist for legal purposes. Recent off-the-cuff remarks by politicians have no basis in law or fact.

Also, Bitcoin isn't domestic to the US or any other country. It's a worldwide community, as can be seen in this [https://bitcointalk.org/?topic=2346.0 map of Bitcoin nodes].

== Bitcoin will only enable tax evaders which will lead to the eventual downfall of civilization ==

Cash transactions hold the same level of anonymity but are still taxed successfully. It is up to you to follow the applicable state laws in your home country, or face the consequences.

While it may be easy to transfer bitcoins anonymously, ''spending'' them anonymously on tangibles is just as hard as spending any other kind of money anonymously. Tax evaders are often caught because their lifestyle and assets are inconsistent with their reported income, and not necessarily because government is able to follow their money.

== Bitcoins can be printed/minted by anyone and are therefore worthless ==

Bitcoins are not printed/minted. Instead, [[Blocks]] are computed by miners and for their efforts they are awarded a specific amount of bitcoins and transaction fees paid by others. See [[Mining]] for more information on how this process works.

== Bitcoins are worthless because they're based on unproven cryptography ==

SHA256 and ECDSA which are used in Bitcoin are well-known industry standard algorithms. SHA256 is endorsed and used by the US Government and is standardized (FIPS180-3 Secure Hash Standard). If you believe that these algorithms are untrustworthy then you should not trust Bitcoin, credit card transactions or any type of electronic bank transfer. Bitcoin has a sound basis in well understood cryptography.

== Early adopters are unfairly rewarded ==

Early adopters are rewarded for taking the higher risk with their time and money. This argument is akin to saying that people who buy stock at a company IPO (Initial Public Offering) are unfairly rewarded. This argument also depends on bitcoin early adopters using bitcoins to store rather than transfer value. The daily trade on the exchanges (as of Jan 2012) indicates that smaller transactions are becoming the norm, indicating trade rather than investment.

In more pragmatic terms, "fairness" is an arbitrary concept that is improbable to be agreed upon by a large population. Establishing "fairness" is no goal of Bitcoin, as this would be impossible.

By starting to mine or acquire bitcoins today, you too can become an early adopter.

== 21 million coins isn't enough; doesn't scale ==

One Bitcoin is divisible down to eight decimal places. There are really 2,099,999,997,690,000 (just over 2 quadrillion) maximum possible atomic units in the bitcoin design.

The value of "1 BTC" represents 100,000,000 of these. In other words, each is divisible by up to 10^8.

As the value of the unit of 1 BTC grows too large to be useful for day to day transactions, people can start dealing in smaller [[Units|units]], such as milli-bitcoins (mBTC) or micro-bitcoins (μBTC).

== Bitcoins are stored in wallet files, just copy the wallet file to get more coins! ==

No, your wallet contains your secret keys, giving you the rights to spend your bitcoins. Think of it like having bank details stored in a file. If you give your bank details (or bitcoin wallet) to someone else, that doesn't double the amount of money in your account. You can spend your money or they can spend your money, but not both.

== Lost coins can't be replaced and this is bad ==

Bitcoins are divisible to 0.00000001, so there being fewer bitcoins remaining is not a problem for the currency itself. If you lose your coins, all other coins will go up in value a little. Consider it a donation to all other bitcoin users.

A related question is: Why don't we have a mechanism to replace lost coins? The answer is that it is impossible to distinguish between a 'lost' coin and one that is simply sitting unused in someone's wallet.

== It's a giant 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. In a ponzi scheme, early adopters can only profit at the expense of late adopters, and the late adopters always lose. Bitcoin has an expected win-win outcome. Early and present adopters profit from the rise in value as Bitcoins become better understood and in turn demanded by the public at large. All adopters benefit from the usefulness of a reliable and widely-accepted decentralized peer-to-peer currency.

== Finite coins plus lost coins means deflationary spiral ==
As deflationary forces may apply, economic factors such as hoarding are offset by human factors that may lessen the chances that a [[Deflationary spiral]] will occur.

== Bitcoin can't work because there is no way to control inflation ==

Inflation is simply a rise of prices over time, which is generally the result of the devaluing of a currency. This is a function of supply and demand. Given the fact that the supply of bitcoins is fixed at a certain amount, unlike fiat money, the only way for inflation to get out of control is for demand to disappear. Temporary inflation is possible with a rapid adoption of Fractional Reserve Banking but will stabilize once a substantial number of the 21 million "hard" bitcoins are stored as reserves by banks.

Given the fact that Bitcoin is a distributed system of currency, if demand were to decrease to almost nothing, the currency would be doomed anyway.

The key point here is that Bitcoin as a currency can't be inflated by any single person or entity, like a government, as there's no way to increase supply past a certain amount.

Indeed, the most likely scenario, as Bitcoin becomes more popular and demand increases, is for the currency to increase in value, or deflate, until demand stabilizes.

== The Bitcoin community consists of anarchist/conspiracy theorist/gold standard 'weenies' ==

The members of the community vary in their ideological stances.

== Anyone with enough computing power can take over the network ==

CONFIRMED, see [[Weaknesses]].

That said, as the network grows, it becomes harder and harder for a single entity to do so. Already the Bitcoin network's computing power is quite ahead of the world's fastest supercomputers, together.

What an attacker can do once the network is taken over is quite limited. Under no circumstances could an attacker create counterfeit coins, fake transactions, or take anybody else's money. An attacker's capabilities are limited to taking back their own money that they very recently spent, and preventing other people's transactions from receiving confirmations. Such an attack would be very costly in resources, and for such meager benefits there is little rational economic incentive to do such a thing.

Furthermore, this attack scenario would only be feasible for as long as it was actively underway. As soon as the attack stopped, the network would resume normal operation.

== Bitcoin violates governmental regulations ==

There is no known governmental regulation which disallows the use of Bitcoin.

See also: the "[[#Bitcoins_are_illegal_because_they.27re_not_legal_tender|Bitcoins are illegal because they're not legal tender]]" myth.

== Fractional reserve banking is not possible ==

It is possible. See the main article, [[Fractional Reserve Banking and Bitcoin]]

== Point of sale with bitcoins isn't possible because of the 10 minute wait for confirmation ==

It is true that transactions [[FAQ#Why_do_I_have_to_wait_10_minutes_before_I_can_spend_money_I_received.3F|can]] sometimes take tens of minutes to become ''confirmed''. Despite this, retailers can accept unconfirmed transactions with very little risk by simply 'listening' on the network for a double-spend transaction, or partnering with a company that provides this service. After a head start of merely several seconds, the original transaction would reach so much of the Bitcoin network that a fraudulent double-spend transaction would almost certainly be fruitless. An attacker would have to commit easily-detectable fraud, in person, several hundred or several thousand times, before one of these low-value double-spend attempts would likely succeed.

An attacker could work around the necessity of sending out a second fraudulent transaction to the Bitcoin network by attempting to [[Mining|solo-mine]] an attack block containing the attack transaction himself - temporarily withholding the block with the rest of the network - and then execute the fraudulent purchase within seconds, or minutes at most, of mining the attack block, before broadcasting the attack block. However, the cost of such an activity would dramatically outweigh the value of anything typically offered without a confirmation wait for several reasons.

First, mining a block (attack or otherwise) entitles the miner to a valuable block reward, and because the attack involves temporarily withholding the block from the network, the attacker would put himself in the likely position of his block becoming [[Stale block|stale]], which would result in forfeiture of the entire reward. Most solo miners solve less than one block per month, so this would represent the loss of proceeds of potentially several weeks of mining.

Second, it is not possible for a solo miner to know exactly when his mining activity will yield a block, and because the attack must be carried out within seconds or minutes of successfully mining a block, the attacker will not be able to know or plan in advance the brief window when the attack would be likely to succeed. While it may be easy for a determined attacker to get low-value items that are sold and delivered online instantly without waiting for confirmations (such as downloads), this unpredictability and the briefness of the opportunity would make it extremely difficult to commit any kind of fraud where real-life interaction is required, such as visiting a merchant or taking possession of goods. Petty shoplifting would be far simpler. Even if an attacker went forward with this attack, the retailer would be notified of the fraud the moment the attack block is released seconds later.

In short, the 10-minute wait for confirmation is only practically necessary when delivering goods of value that significantly exceed the block reward an attacker would have to risk to perform an attack and where recourse after delivery is practically nonexistent, such as money transfers.

== After 21 million coins are mined, no one will generate new blocks ==

When operating costs can't be covered by the block creation bounty, which will happen some time before the total amount of BTC is reached, miners will earn some profit from [[transaction fees]]. However unlike the block reward, there is [http://bitcoin.stackexchange.com/questions/876/how-much-will-transaction-fees-eventually-be/895#895 no coupling between transaction fees and the need for security], so there is less of a guarantee that the amount of [[Mining|mining]] being performed will be sufficient to maintain the network's security.

== Bitcoin has no built-in chargeback mechanism, and this isn't good ==

'''Why some people think this is bad''': Chargebacks are useful for limiting fraud. The person handling your money has a responsibility to prevent fraud. If you buy something on eBay and the seller never ships it, PayPal takes funds from the seller's account and gives you back the money. This strengthens the eBay economy, because people recognize that their risk is limited and are more willing to purchase items from risky sellers.

'''Why it's actually a good thing''': Bitcoin is designed such that your money is yours and yours alone. Allowing chargebacks implies that it is possible for another entity to take your money from you. You can have either total ownership rights of your money, or fraud protection, but not both. That said, nothing inherent in the dollar or euro or any other currency is necessary for chargebacks to be possible, and likewise, nothing prevents the creation of PayPal-like services denominated in Bitcoin that provide chargebacks or fraud protection.

The statement "The person handling your money has a responsibility to prevent fraud" is still true; the power has been shifted into your own hands. Fraud will always exist. It's up to you to only send bitcoins to trusted entities. It is possible to trust an online identity without ever knowing their physical identity; see the [http://wiki.bitcoin-otc.com/wiki/OTC_Rating_System OTC Web of Trust].

== Quantum computers would break Bitcoin's security ==

While ECDSA is indeed not secure under quantum computing, quantum computers don't yet exist and probably won't for a while.
The DWAVE system often written about in the press is, even if all their claims are true, not a quantum computer of a kind that could be used for cryptography.
Bitcoin's security, when used properly with a new address on each transaction, depends on more than just ECDSA: Cryptographic hashes are much stronger than ECDSA under QC.
Bitcoin's security was designed to be upgraded in a forward compatible way and could be [http://en.wikipedia.org/wiki/Post-quantum_cryptography upgraded] if this were considered an imminent threat.

See the implications of quantum computers on public key cryptography here http://en.wikipedia.org/wiki/Quantum_computer#Potential

The ''risk'' of quantum computers is also there for financial institutions, like banks, because they heavily rely on cryptography when doing transactions.

== [[Mining|Bitcoin mining]] is a waste of energy and harmful for ecology ==

No more so than the wastefulness of mining gold out of the ground, melting it down and shaping it into bars, and then putting it back underground again. Not to mention the building of big fancy buildings, the waste of energy printing and minting all the various fiat currencies, the transportation thereof in armored cars by no less than two security guards for each who could probably be doing something more productive, etc.

As far as mediums of exchange go, Bitcoin is actually quite economical of resources, compared to others.

'''Economic Argument 1'''

[[Mining|Bitcoin mining]] is a highly competitive, dynamic, almost [http://en.wikipedia.org/wiki/Perfect_market perfect], market. Mining rigs can be set up and dismantled almost anywhere in the world with relative ease. Thus, market forces are constantly pushing mining activity to ''places'' and ''times'' where the marginal price of electricity is low or zero. These electricity products are cheap for a reason. Often it’s because the electricity is difficult (and wasteful) to transport, difficult to store, or because there is low demand and high supply. Using electricity in this way is a lot less wasteful than simply plugging a mining rig into the mains indiscriminately.

For example, Iceland produces an excess of cheap electricity from renewable sources, but it has no way of exporting electricity because of its remote location. It is conceivable that at some point in future Bitcoin mining will only be profitable in places like Iceland, and unprofitable in places like central Europe, where electricity comes mostly from nuclear and fossil sources.

Market forces could even push mining into innovative solutions that have an effective electricity consumption of ''zero''. Mining always produces heat equivalent to the energy consumed - for example, 1000 watts of mining equipment produces the same amount of heat as a 1000 watt heating element used in an electric space heater, hot tub, water heater, or similar appliance. Someone already in a willing position to incur the cost of electricity for its heat value alone could run mining equipment specially designed to mine bitcoins while capturing and utilizing the heat produced, without incurring any energy costs beyond what they already intended to spend on heating.

'''Economic Argument 2'''

When the environmental costs of mining are considered, they need to be weighed up against the benefits. If you question Bitcoin on the grounds that it consumes electricity, then you should also ask questions like this: Will Bitcoin promote economic growth by freeing up trade? Will this speed up the rate of technological innovation? Will this lead to faster development of green technologies? Will Bitcoin enable new, border crossing [http://en.wikipedia.org/wiki/Smart_grid smart grid] technologies? …

Dismissal of Bitcoin because of its costs, while ignoring its benefits, is a dishonest argument. In fact, any environmental argument of this type is dishonest, not just pertaining to Bitcoin. Along similar lines, it could be argued that wind turbines are bad for the environment because making the steel structure consumes energy.

== Shopkeepers can't seriously set prices in bitcoins because of the volatile exchange rate ==

Your assumption is that bitcoins must be sold immediately to cover operating expenses. If the shopkeeper's back-end expenses were transacted in bitcoins as well, then the exchange rate would be irrelevant. Larger adoption of Bitcoin would make prices [http://en.wikipedia.org/wiki/Sticky_%28economics%29 sticky]. Future volatility is expected to decrease, as the size and depth of the market grows.

In the meantime, many merchants simply regularly pull the latest market rates from the exchanges and automatically update the prices on their websites. Also you might be able to buy a put option in order to sell at a fixed rate for a given amount of time. This would protect you from drops in price and simplify your operations for that time period.

== Like Flooz and e-gold, bitcoins serve as opportunities for criminals and will be shut down ==

* Visa, MasterCard, PayPal, and cash all serve as opportunities for criminals as well, but society keeps them around due to their recognized net benefit.
* Hopefully Bitcoin will grow to the point where no single organization can disrupt the network, or would be better served by helping it.
* Terrorists fly aircraft into buildings, but the governments have not yet abolished consumer air travel. Obviously the public good outweighs the possible bad in their opinion.
* Criminal law differs between jurisdictions.

== Bitcoins will be shut down by the government just like Liberty Dollars were ==

Liberty Dollars started as a commercial venture to establish an alternative US currency, including physical banknotes and coins, backed by precious metals. This, in and of itself, is not illegal. They were prosecuted under counterfeiting laws because the silver coins allegedly resembled US currency.

Bitcoins do not resemble the currency of the US or of any other nation in any way, shape, or form. The word "dollar" is not attached to them in any way. The "$" symbol is not used in any way.

Bitcoins have no representational similarity whatsoever to US dollars.

Of course, actually 'shutting down' Liberty Dollars was as easy as arresting the head of the company and seizing the offices and the precious metals used as backing. The decentralized Bitcoin, with no leader, no servers, no office, and no tangible asset backing, does not have the same vulnerability.

== Bitcoin is not decentralized because the developers can dictate the software's behavior ==

The Bitcoin protocol was originally defined by Bitcoin's inventor, [[Satoshi Nakamoto]], and this protocol has now been widely accepted as the standard by the community of miners and users.

Though the developers of the original Bitcoin client still exert influence over the Bitcoin community, their power to arbitrarily modify the protocol is very limited. Since the release of Bitcoin v0.3, changes to the protocol have been minor and always in agreement with community consensus.

Protocol modifications, such as increasing the block award from 25 to 50 BTC, are not compatible with clients already running in the network. If the developers were to release a new client that the majority of miners perceives as corrupt, or in violation of the project’s aims, that client would simply not catch on, and the few users who do try to use it would find that their transactions get rejected by the network.

There are also other [[:Category:Clients|Bitcoin clients made by other developers]] that adhere to the Bitcoin protocol. As more developers create alternative clients, less power will lie with the developers of the original Bitcoin client.

== Bitcoin is a pyramid scheme ==

Bitcoin is nearly opposite of a pyramid scheme in a mathematical sense. Because Bitcoins are algorithmically made scarce, no exponential benefit is derived from introducing new users to use of it. There is a quantitative benefit in having additional interest or demand, but this is in no way exponential.

== Bitcoin was hacked ==

In the history of Bitcoin, there has never been an attack on the [[block chain]] that resulted in stolen money from a confirmed output. Neither has there ever been a reported theft resulting directly from a vulnerability in the [[Original Bitcoin client|original Bitcoin client]], or a vulnerability in the protocol. Bitcoin is secured by standard cryptographic functions. These functions have been peer reviewed by cryptography experts and are considered unlikely to be breakable in the foreseeable future.

It is safe to say that the currency itself has never been 'hacked'. However, several major ''websites'' using the currency have been hacked, often resulting in high profile Bitcoin heists. These heists are misreported in some media as hacks on Bitcoin itself. An analogy: Just because someone stole US dollars from a supermarket till, doesn’t mean that the US dollar as a currency has been 'hacked'.

Most bitcoin thefts are the result of inadequate [[Securing your wallet|wallet security]]. In response to the wave of thefts in 2011 and 2012, the community has developed risk-mitigating measures such as [[Wallet_encryption|wallet encryption]], support for [[BIP_0011|multiple signatures]], [[How_to_set_up_a_secure_offline_savings_wallet|offline wallets]], [[Paper_wallet|paper wallets]], and [[Hardware_wallet|hardware wallets]]. As these measures gain adoption by merchants and users, it is expected that the number of thefts will drop.

[[de:Mythen]]

Software

2013-03-26T10:32:15Z

Alvox: /* Bitcoin clients */ Link to proper Clients article

List of Bitcoin-related software. See also [[:Category:Software|Category:Software]].

Be sure to keep on top of the latest [[CVEs|security vulnerabilities]]!

==Bitcoin clients==
===Bitcoin clients===
::''Main article and feature comparison: [[Clients]]''
*[[Bitcoin-Qt]] - C++/Qt based tabbed UI. Linux/MacOSX/Windows. Full-featured [[Thin Client Security|thick client]] that downloads the entire [[block chain]], using code from the original Bitcoin client.
*[[bitcoind]] - GUI-less version of the original Bitcoin client, providing a [[API reference (JSON-RPC)|JSON-RPC]] interface
*[[MultiBit]] - lightweight [[Thin Client Security|thin client]] for Windows, MacOS and Linux with support for opening multiple wallets simultaneously
*[[Electrum]] - a "blazing fast, open-source, multi-OS Bitcoin client/wallet with a very active community"
*[[Bitcoin-js-remote]] - JavaScript RPC client, support for QR codes
*[https://github.com/TheSeven/Bitcoin-WebUI Bitcoin WebUI] - JavaScript RPC client
*[https://github.com/zamgo/bitcoin-webskin Bitcoin Webskin] - PHP web interface to bitcoind and namecoind
*[https://bitcointalk.org/index.php?topic=50721.0 subvertx] - command line bitcoin tools
*[[Bitcoiner]] - Java RPC client (Android)
*[[Armory]] - Python-based client currently an alpha-level release, the beta version is being crowdfunded
*[[Spesmilo]] - Python/PySide RPC client (abandoned)

====Frontends to eWallet====
*[[BitPay]] - Android application
*[https://blockchain.info/wallet Blockchain] - Javascript bitcoin client with client side encryption.

====Experimental====
*[[Freecoin]] - C++ client, supports alternative currencies like [[Beertoken]]
*[[BitDroid]] - Java client
*[[Bitdollar]] - C++/Qt client, unstable beta version

===Libraries===
*[https://bitcointalk.org/index.php?topic=30646.0 libbitcoin]
*[[BitCoinJ]] - Java client library, early development stage but used in live projects already
*[[BCCAPI]] (Bitcoin Client API) - a java library designed for making secure light-weight bitcoin clients.

==Bitcoin Trade Data==
*[[Bitcoin Charts]] – Prices, volume, and extensive charting on virtually all Bitcoin markets.
*[[MtGox Live]] - An innovative chart showing a live feed of [[MtGox]] trades and market depth. (Must Use Chrome)
*[http://btccharts.com BTCCharts] - An innovative chart showing a live feed of multiple markets, currencies and timeframes.
*[http://BitcoinExchangeRate.org BitcoinExchangeRate.org] - Bitcoin and USD converter with convenient URL scheme and Auto-updating Portfolio Spreadsheet.
*[[Bitcoin Sentiment Index]] - A financial index that collects and disseminates sentiment data about bitcoin.
*[[Preev]] - Bitcoin converter with live exchange rates.
*[[Skami]] - Bitcoin Market Exchange comparison charts.
*[[BitcoinSentiment]] - Crowdvoting site offering means of voting and viewing voters sentiment towards bitcoin.

==Bitcoin software==

===Web interfaces for merchants===
*[[Bitcoin Evolution]] - Non wallet-based Buy Now button to insert into websites (handles sales tracking; client must be used for actual transaction)
*[[BitPay]] - Buy Now buttons, Checkout posts/callbacks, Mobile Checkout, JSON API
*[[Btceconomy]] - a JavaScript widget listing items for sale
*[[Javascript Bitcoin Converter]] - currency conversion
*[[WalletBit]] - Easy JavaScript Buy Now buttons, Instant Payment Notification, Application Programming Interface (JSON API), Mobile Checkout, QR-Code
*[[BitUtils Merchant]] - Customizable Buy Now buttons with hosted checkout interface. No programming skills required to set up.

===Shopping Cart Integration in eCommerce-Systems===
*[[Zen Cart Bitcoin Payment Module]] - a payment module that interacts with bitcoind for the Zen Cart eCommerce shopping chart.
*[[Karsha Shopping Cart Interface]] - is a mobile payment-interface which enables its users to accept payments.
*[[Bitcoin-Cash]] - an easy to use payment module for xt:Commerce
*[[BitPay]] - bitcoin plugins for Magento, Opencart, Zencart, PHP, JSON API
*[[WalletBit]] - Plugins for PrestaShop, OpenCart, PHP, JSON API
*[[OpenCart Bitcoin]] - An OpenCart payment module that communicates with a bitcoin client using JSON RPC.
*[[OsCommerce_Bitcoin_Payment_Module|OsCommerce Bitcoin Payment Module]] - a payment module that uses a python monitoring script to interact with bitcoind for OsCommerce
* [http://drupal.org/project/uc_bitcoin Drupal Ubercart Bitcoin payment method] enables you to accept Bitcoin as payment for your Drupal/Ubercart enabled website product/services.

===Web apps (opensource)===
*[[Bitcoin Central]] - currency exchange
*[[Bitcoin Poker Room]] - poker site
*[[Abe]] - block chain viewer
*[[Simplecoin]] - PHP web frontend for a pool
*[[bitcoin_simple_php_tools]] simple php tools for webmasters

===Browser extensions===
*[[Bitcoin Extension]] - check balance and send bitcoins (Chrome)
*[[Bitcoin Prices (extension)]] - monitoring price (Firefox)
*[[Bitcoin Ticker]] - monitoring price (Chrome)
*[[Biticker]] - Bitcoin ticker, currency converter and history price graph (Chrome)
*[https://chrome.google.com/webstore/detail/bitcoin-microformats/bkanicejfbhlidgjkpenmddnacjengld?hl=en Bitcoin Microformats] Show bitcoin address metadata embedded in a page (Chrome)
*[https://chrome.google.com/webstore/detail/bitcoin-address-lookup/pmlblkdmadbidammhjiponepngbfcpge?hl=en Bitcoin Address Lookup] Right click an address to view its value. (Chrome)

===PC apps===
*[[http://www.mybtc-trader.com MyBTC-Trader.com]] - a MtGox Bitcoin trading client for windows with GUI
*[[Mining Explorer]] - monitoring tool for bitcoin mining
*[[Bitcoin SMS Alert]] - sends SMS text alerts to a user's phone based on BTC price / percent thresholds.
*[[BTConvert]] - currency conversion
*[[Sierra Chart MtGox Bridge]] - real-time charting
*[[BitTicker]] - monitoring price (Mac OS X)
*[[ToyTrader]] - a command line trading tool for [[MtGox]]
*[[goxsh]] - a command-line frontend to the [[MtGox|Mt. Gox Bitcoin Exchange]] (Python)
*[[MyBitcoins gadget]] - monitoring pool earnings / price (Windows gadget)
*[[Bitcoin QR Popup]] - streamlined interface to bitcoin for POS systems (Windows)
*[http://gnome-help.org/content/show.php/Bitcoin+Rate?content=138572 Bitcoin Rate] - Desktop widget with BTC exchange rate (KDE)
*[http://kde-apps.org/content/show.php?content=142344 Bitcoin Monitor] - Desktop widget to monitor status of your Bitcoin miners on mining pools (KDE)

===Mobile apps===
==== iPhone / iPad ====
*[https://blockchain.info/wallet/iphone-app Blockchain] - Fully featured iphone bitcoin app.
*[[Bitcoin Ticker (iPhone)]] - monitoring price w/push notifications
*[[BitCoins Mobile]] - First iPad native app! Live market data, news feeds, mining pool statistics, full screen exchange price charts, bitcoin network statistical charts. (iPad only, iPhone/iPod Touch coming soon!)
*[https://github.com/teeman/BitcoinTrader BitcoinTrader] - Spend/receive BTC via QR codes, trade, deposit/withdraw, etc. Supports Mt. Gox, TradeHill, ExchB, CampBX, and InstaWallet.
*[[Bit-pay]] - Mobile Checkout, set prices in any currency and receive mobile-to-mobile payment
*[[Easywallet.org]] - Web based wallet, works with QR Code scanner on iPhone/iPad/iPod touch

==== Android ====
* Direct link to Android Market bitcoin apps. https://play.google.com/store/search?q=bitcoin
*[[BitCare]] - Track bitcoin wallet balance, trade on Mt.Gox, monitor mining pool hashrate, balance, worker status.
*[[BtcMobile]] - monitoring price and mining pool statistics (iPhone/iPad, Android)
*[[Bitcoin Alert]] - monitoring price (Android)
*[[Bitcoin-android]] - Does not appear to be being maitained anymore. https://market.android.com/details?id=com.bitcoinandroid
*[[Bitcoin Wallet Balance]] - view your balance in real time on your android phone
*[[Bitcoin Wallet for Android]] - This is the most functional android bitcoin wallet application. https://market.android.com/details?id=de.schildbach.wallet
*[[BitcoinSpinner]] - Single address, easy to use, lightweight and open source client. Keys stored on device.
*[[BitcoinX]] - monitoring price (Android)
*[[BitPay]] - https://market.android.com/details?id=com.bitcoin.bitpay (Is not related to the bit-pay.com online payment processor.)
*[https://blockchain.info/wallet/android-app Blockchain] - Lightweight Android Bitcoin Client - Also works with blockchain.info web interface and iphone app.
*[[BtcMobile]] - monitoring price and mining pool statistics (iPhone/iPad, Android)
*[[Easywallet.org]] - Web based wallet, works with QR Code scanner on Android devices
*[[Miner Status]] - monitoring miner status (Android)
*[[SMS Bitcoins]] - transactions by SMS

==== Windows Phone 7 ====
*Direct link to Windows Phone Marketplace Bitcoin apps: [http://www.windowsphone.com/en-us/store/search?q=bitcoin]

see also [[Bitcoin Payment Apps]]

===Operating systems===
*[[BAMT]]
*[[LinuxCoin]] - a lightweight Debian-based OS, with the Bitcoin client and GPU mining software

===Mining apps===
Main page: [[Mining software]]
*[[50Miner]] - A GUI frontend for Windows(Poclbm, Phoenix, DiabloMiner, cgminer)
*[[BFGMiner]] - Modular FPGA/GPU miner in C
*[[BTCMiner]] - Bitcoin Miner for ZTEX FPGA Boards
*[[Bit Moose]] - Run Miners as a Windows Service.
*[[Poclbm]] - Python/OpenCL GPU miner ([[Poclbm-gui|GUI(Windows & MacOS X)]])
*[[Poclbm-mod]] - more efficient version of [[Poclbm]] ([[Poclbm-mod-gui|GUI]])
*[[DiabloMiner]] - Java/OpenCL GPU miner ([[DiabloMiner.app|MAC OS X GUI]])
*[[RPC Miner]] - remote RPC miner ([[RPCminer.app|MAC OS X GUI]])
*[[Phoenix miner]] - miner
*[[Cpu Miner]] - miner
*[[Ufasoft miner]] - miner
*[[Pyminer]] - Python miner, reference implementation
*[[Remote miner]] - mining pool software
*[[Open Source FGPA Bitcoin Miner]] - a miner that makes use of an FPGA Board
*[https://github.com/mkburza/Flash-Player-Bitcoin-Miner Flash Player Bitcoin Miner] - A proof of concept Adobe Flash Player miner

===Mining Pool Servers (backend)===
Main page: [[Poolservers]]

*[[ecoinpool]] - Erlang poolserver
*[[Eloipool]] - Fast Python3 poolserver
*[[Pushpoold]] - Old mining poolserver in C (not maintained)
*[[Poold]] - Old Python mining poolserver (not maintained)
*[[PoolServerJ]] - Java mining poolserver (not maintained)

===Utilities, libraries, and interfaces:===
*[[BitcoinCrypto]] - a lightweight Bitcoin crypto library for Java/Android
*[[Bitcoin Dissector]] - a wireshark dissector for the bitcoin protocol
*[[Bitcointools]] - a set of Python tools accessing the transaction database and the wallet
*[[Finance::MtGox]] - a Perl module which interfaces with the Mt. Gox API
*[[libblkmaker]] - C library implementation of [[getblocktemplate]] decentralized mining protocol
*[[python-blkmaker]] - Python module implementation of [[getblocktemplate]] decentralized mining protocol

===Lists of software===
*[[BitGit]] - list of Bitcoin-related opensource projects hosted at Git

===Developer resources===
*[[:Category:Developer|Category:Developer]]
*[[:Category:Technical|Category:Technical]]
*[[Original Bitcoin client/API calls list]]
*[[API reference (JSON-RPC)]]
*[[PHP_developer_intro|PHP Developer Introduction]]

===Other===
*[[Namecoin]] - a distributed naming system based on Bitcoin technology
*[[Bitcoin Consultancy]] - an organization providing open source software and Bitcoin-related consulting
*[[Open Transactions]] - a financial crypto and digital cash software library, complementary to Bitcoin
*[[Moneychanger]] - Java-based GUI for [[Open Transactions]]
*[http://btcnames.org/ BTCnames] - a webbased aliasing service which allows to handle unlimited names for your BTC deposit hashes
*[[Devcoin]] - the open source developer coin

Clients

2013-03-26T10:25:31Z

Alvox: Updated numbers as of March 2013, with ~75% of the blockchain wasted by SatoshiDice. MultiBit synchronized with the network in a few seconds on a ~5Mbps connection.

==Overview==

This table compares the features of the different clients. All of the listed clients are open-source.

===Feature key===

; Wallet Security : How well the client protects your [[private key]]s from people with access to the machine the wallet is stored on. The private keys can be encrypted, for example. The private keys can also be either stored on your device or on a remote server.
; Network Security : Clients which more fully implement the Bitcoin network protocol are safer -- they can't be as easily tricked by powerful attackers. A client which ''fully'' implements the protocol will always use the correct [[block chain]] and will never allow [[double-spending|double-spends]] or invalid transactions to exist in the block chain under any circumstances. Clients which only ''partially'' implement the protocol typically trust that 50% or more of the network's mining power is honest. Some clients trust one or more ''remote servers'' to protect them from double-spends and other network attacks.
; Setup Time : Some clients require that you download and verify a large amount of data before you can send or receive BTC.
; Maturity : When the project was started.

===Table===


{| class='wikitable' style='text-align: center'
! Client !! Get Started !! Audience !! Wallet Security !! Network Security !! Backups !! Setup Time !! Disk Space !! Maturity !! Multi-user !! Available for
|-
! Armory
|| [http://bitcoinarmory.com/index.php/get-armory Download] || Power users || {{CLGood|Encrypted, on-device}} || Addon || {{CLBest|One-time}} || Varies || {{CLBad|6+ GB}} || Jul 2011 || {{CLBest|Multi-wallet}} || {{CLLinux}}{{CLWin}}
|-
! Bitcoin Wallet
|| [https://play.google.com/store/apps/details?id=de.schildbach.wallet Google Play] [https://appworld.blackberry.com/webstore/content/23952882/ BlackBerry World] || {{CLBest|Everyone}} || {{CLGood|Isolated, on-device}} || Partial || Manual || 1 hour || 30 MB || {{CLGood|Mar 2011}} || on JB tablets || {{CLAndroid}} [[file:ico-blackberry.png]]
|-
! {{CLGood|Bitcoin-Qt}}
|| [http://sourceforge.net/projects/bitcoin/files/Bitcoin/ Download] || {{CLGood|End-users}} || {{CLGood|Encrypted, on-device}} || {{CLBest|Full}} || Manual || {{CLBad|Hours - days}} || {{CLBad|6+ GB}} || {{CLGood|May 2011}} || No || {{CLLinux}}{{CLMac}}{{CLWin}}
|-
! bitcoind
|| [http://sourceforge.net/projects/bitcoin/files/Bitcoin/ Download] || Programmers || {{CLGood|Encrypted, on-device}} || {{CLBest|Full}} || Manual || {{CLBad|Hours - days}} || {{CLBad|6+ GB}} || {{CLBest|Aug 2009}} || {{CLGood|Virtual accounts}} || {{CLLinux}}{{CLWin}}
|-
! Electrum
|| [http://ecdsa.org/electrum/ Download] || Power users || {{CLGood|Encrypted, on-device}} || Minimal || {{CLBest|Memorized}} || {{CLGood|Minutes}} || {{CLGood|5 MB}} || Nov 2011 || No || {{CLLinux}}{{CLWin}}
|-
! MultiBit
|| [http://multibit.org/releases.html Download] || {{CLGood|End-users}} || {{CLBad|None, on-device}} || Partial || {{CLBad|No}} || {{CLBest|Seconds}} || 50 MB || Jul 2011 || {{CLBest|Multi-wallet}} || {{CLLinux}}{{CLMac}}{{CLWin}}
|-
! My Wallet
|| [https://blockchain.info/wallet/new Web-based] || {{CLBest|Everyone}} || Encrypted, on a server || {{CLBad|Remote}} || {{CLGood|Automatic}} || {{CLGood|Minutes}} || {{CLBest|None}} || Dec 2011 || {{CLBest|Yes}} || {{CLAndroid}}{{CLiOS}}{{CLLinux}}{{CLMac}}{{CLWin}}
|}



==For developers==

This table shows additional information about various Bitcoin clients that may be relevant to developers.

{| class='wikitable' style='text-align: center'
! Client !! Website !! Source Code !! License !! Discussion !! Architecture
|-
! Armory
|| [http://bitcoinarmory.com/ Link] ||[https://github.com/etotheipi/BitcoinArmory/ Github] || AGPLv3 || [https://bitcointalk.org/index.php?board=97.0 Bitcointalk] || Integrated
|-
! Bitcoin Wallet
|| [https://code.google.com/p/bitcoin-wallet/ Link] || [https://code.google.com/p/bitcoin-wallet/source/checkout Google Code] [https://github.com/schildbach/bitcoin-wallet Github] || GPLv3 || [https://bitcointalk.org/index.php?board=100.0 Bitcointalk] / [https://groups.google.com/forum/?fromgroups#!forum/bitcoinj Google Groups] || [[Thin Client Security#Simplified Payment Verification (SPV)|SPV]]
|-
! Bitcoin-Qt / bitcoind
|| [http://bitcoin.org/ Link] || [https://github.com/bitcoin/bitcoin Github] || MIT || [https://lists.sourceforge.net/lists/listinfo/bitcoin-development Sourceforge] || Integrated
|-
! Electrum
|| [http://ecdsa.org/electrum/ Link] || [https://gitorious.org/electrum Gitorious] || GPLv3 || [https://lists.sourceforge.net/lists/listinfo/electrum-discuss Sourceforge] || [[Thin Client Security#Server-Trusting Clients|Server-Client]]
|-
! MultiBit
|| [http://multibit.org/ Link] || [https://github.com/jim618/multibit Github] || MIT || [https://groups.google.com/forum/?fromgroups#!forum/bitcoin-multibit Google Groups] || [[Thin Client Security#Simplified Payment Verification (SPV)|SPV]]
|-
! My Wallet
|| [https://blockchain.info/wallet/ Link] || [https://github.com/blockchain/My-Wallet/ Github] || BSD* || None || [[Thin Client Security#Server-Trusting Clients|Server-Client]]
|}

==See Also==
* [[Software#Bitcoin_clients|List of clients]]
* [[Bitcoin Ladder]]

<references/>

Software

2013-03-25T04:20:21Z

Alvox: /* Bitcoin clients */ Rearrange the list and add info about the original client and MultiBit

List of Bitcoin-related software. See also [[:Category:Software|Category:Software]].

Be sure to keep on top of the latest [[CVEs|security vulnerabilities]]!

==Bitcoin clients==
===Bitcoin clients===
*[[Bitcoin-Qt]] - The original client. C++/Qt based tabbed UI. Linux/MacOSX/Windows. Full-featured [[Thin Client Security|thick client]] that downloads the entire [[block chain]].
**[[bitcoind]] - GUI-less version of the original Bitcoin client, providing a [[API reference (JSON-RPC)|JSON-RPC]] interface
*[[MultiBit]] - lightweight [[Thin Client Security|thin client]] for Windows, MacOS and Linux with support for opening multiple wallets simultaneously
*[[Electrum]] - a "blazing fast, open-source, multi-OS Bitcoin client/wallet with a very active community"
*[[Bitcoin-js-remote]] - JavaScript RPC client, support for QR codes
*[https://github.com/TheSeven/Bitcoin-WebUI Bitcoin WebUI] - JavaScript RPC client
*[https://github.com/zamgo/bitcoin-webskin Bitcoin Webskin] - PHP web interface to bitcoind and namecoind
*[https://bitcointalk.org/index.php?topic=50721.0 subvertx] - command line bitcoin tools
*[[Bitcoiner]] - Java RPC client (Android)
*[[Armory]] - Python-based client currently an alpha-level release, the beta version is being crowdfunded
*[[Spesmilo]] - Python/PySide RPC client (abandoned)

====Frontends to eWallet====
*[[BitPay]] - Android application
*[https://blockchain.info/wallet Blockchain] - Javascript bitcoin client with client side encryption.

====Experimental====
*[[Freecoin]] - C++ client, supports alternative currencies like [[Beertoken]]
*[[BitDroid]] - Java client
*[[Bitdollar]] - C++/Qt client, unstable beta version

===Libraries===
*[https://bitcointalk.org/index.php?topic=30646.0 libbitcoin]
*[[BitCoinJ]] - Java client library, early development stage but used in live projects already
*[[BCCAPI]] (Bitcoin Client API) - a java library designed for making secure light-weight bitcoin clients.

==Bitcoin Trade Data==
*[[Bitcoin Charts]] – Prices, volume, and extensive charting on virtually all Bitcoin markets.
*[[MtGox Live]] - An innovative chart showing a live feed of [[MtGox]] trades and market depth. (Must Use Chrome)
*[http://btccharts.com BTCCharts] - An innovative chart showing a live feed of multiple markets, currencies and timeframes.
*[http://BitcoinExchangeRate.org BitcoinExchangeRate.org] - Bitcoin and USD converter with convenient URL scheme and Auto-updating Portfolio Spreadsheet.
*[[Bitcoin Sentiment Index]] - A financial index that collects and disseminates sentiment data about bitcoin.
*[[Preev]] - Bitcoin converter with live exchange rates.
*[[Skami]] - Bitcoin Market Exchange comparison charts.
*[[BitcoinSentiment]] - Crowdvoting site offering means of voting and viewing voters sentiment towards bitcoin.

==Bitcoin software==

===Web interfaces for merchants===
*[[Bitcoin Evolution]] - Non wallet-based Buy Now button to insert into websites (handles sales tracking; client must be used for actual transaction)
*[[BitPay]] - Buy Now buttons, Checkout posts/callbacks, Mobile Checkout, JSON API
*[[Btceconomy]] - a JavaScript widget listing items for sale
*[[Javascript Bitcoin Converter]] - currency conversion
*[[WalletBit]] - Easy JavaScript Buy Now buttons, Instant Payment Notification, Application Programming Interface (JSON API), Mobile Checkout, QR-Code
*[[BitUtils Merchant]] - Customizable Buy Now buttons with hosted checkout interface. No programming skills required to set up.

===Shopping Cart Integration in eCommerce-Systems===
*[[Zen Cart Bitcoin Payment Module]] - a payment module that interacts with bitcoind for the Zen Cart eCommerce shopping chart.
*[[Karsha Shopping Cart Interface]] - is a mobile payment-interface which enables its users to accept payments.
*[[Bitcoin-Cash]] - an easy to use payment module for xt:Commerce
*[[BitPay]] - bitcoin plugins for Magento, Opencart, Zencart, PHP, JSON API
*[[WalletBit]] - Plugins for PrestaShop, OpenCart, PHP, JSON API
*[[OpenCart Bitcoin]] - An OpenCart payment module that communicates with a bitcoin client using JSON RPC.
*[[OsCommerce_Bitcoin_Payment_Module|OsCommerce Bitcoin Payment Module]] - a payment module that uses a python monitoring script to interact with bitcoind for OsCommerce
* [http://drupal.org/project/uc_bitcoin Drupal Ubercart Bitcoin payment method] enables you to accept Bitcoin as payment for your Drupal/Ubercart enabled website product/services.

===Web apps (opensource)===
*[[Bitcoin Central]] - currency exchange
*[[Bitcoin Poker Room]] - poker site
*[[Abe]] - block chain viewer
*[[Simplecoin]] - PHP web frontend for a pool
*[[bitcoin_simple_php_tools]] simple php tools for webmasters

===Browser extensions===
*[[Bitcoin Extension]] - check balance and send bitcoins (Chrome)
*[[Bitcoin Prices (extension)]] - monitoring price (Firefox)
*[[Bitcoin Ticker]] - monitoring price (Chrome)
*[[Biticker]] - Bitcoin ticker, currency converter and history price graph (Chrome)
*[https://chrome.google.com/webstore/detail/bitcoin-microformats/bkanicejfbhlidgjkpenmddnacjengld?hl=en Bitcoin Microformats] Show bitcoin address metadata embedded in a page (Chrome)
*[https://chrome.google.com/webstore/detail/bitcoin-address-lookup/pmlblkdmadbidammhjiponepngbfcpge?hl=en Bitcoin Address Lookup] Right click an address to view its value. (Chrome)

===PC apps===
*[[http://www.mybtc-trader.com MyBTC-Trader.com]] - a MtGox Bitcoin trading client for windows with GUI
*[[Mining Explorer]] - monitoring tool for bitcoin mining
*[[Bitcoin SMS Alert]] - sends SMS text alerts to a user's phone based on BTC price / percent thresholds.
*[[BTConvert]] - currency conversion
*[[Sierra Chart MtGox Bridge]] - real-time charting
*[[BitTicker]] - monitoring price (Mac OS X)
*[[ToyTrader]] - a command line trading tool for [[MtGox]]
*[[goxsh]] - a command-line frontend to the [[MtGox|Mt. Gox Bitcoin Exchange]] (Python)
*[[MyBitcoins gadget]] - monitoring pool earnings / price (Windows gadget)
*[[Bitcoin QR Popup]] - streamlined interface to bitcoin for POS systems (Windows)
*[http://gnome-help.org/content/show.php/Bitcoin+Rate?content=138572 Bitcoin Rate] - Desktop widget with BTC exchange rate (KDE)
*[http://kde-apps.org/content/show.php?content=142344 Bitcoin Monitor] - Desktop widget to monitor status of your Bitcoin miners on mining pools (KDE)

===Mobile apps===
==== iPhone / iPad ====
*[https://blockchain.info/wallet/iphone-app Blockchain] - Fully featured iphone bitcoin app.
*[[Bitcoin Ticker (iPhone)]] - monitoring price w/push notifications
*[[BitCoins Mobile]] - First iPad native app! Live market data, news feeds, mining pool statistics, full screen exchange price charts, bitcoin network statistical charts. (iPad only, iPhone/iPod Touch coming soon!)
*[https://github.com/teeman/BitcoinTrader BitcoinTrader] - Spend/receive BTC via QR codes, trade, deposit/withdraw, etc. Supports Mt. Gox, TradeHill, ExchB, CampBX, and InstaWallet.
*[[Bit-pay]] - Mobile Checkout, set prices in any currency and receive mobile-to-mobile payment
*[[Easywallet.org]] - Web based wallet, works with QR Code scanner on iPhone/iPad/iPod touch

==== Android ====
* Direct link to Android Market bitcoin apps. https://play.google.com/store/search?q=bitcoin
*[[BitCare]] - Track bitcoin wallet balance, trade on Mt.Gox, monitor mining pool hashrate, balance, worker status.
*[[BtcMobile]] - monitoring price and mining pool statistics (iPhone/iPad, Android)
*[[Bitcoin Alert]] - monitoring price (Android)
*[[Bitcoin-android]] - Does not appear to be being maitained anymore. https://market.android.com/details?id=com.bitcoinandroid
*[[Bitcoin Wallet Balance]] - view your balance in real time on your android phone
*[[Bitcoin Wallet for Android]] - This is the most functional android bitcoin wallet application. https://market.android.com/details?id=de.schildbach.wallet
*[[BitcoinSpinner]] - Single address, easy to use, lightweight and open source client. Keys stored on device.
*[[BitcoinX]] - monitoring price (Android)
*[[BitPay]] - https://market.android.com/details?id=com.bitcoin.bitpay (Is not related to the bit-pay.com online payment processor.)
*[https://blockchain.info/wallet/android-app Blockchain] - Lightweight Android Bitcoin Client - Also works with blockchain.info web interface and iphone app.
*[[BtcMobile]] - monitoring price and mining pool statistics (iPhone/iPad, Android)
*[[Easywallet.org]] - Web based wallet, works with QR Code scanner on Android devices
*[[Miner Status]] - monitoring miner status (Android)
*[[SMS Bitcoins]] - transactions by SMS

==== Windows Phone 7 ====
*Direct link to Windows Phone Marketplace Bitcoin apps: [http://www.windowsphone.com/en-us/store/search?q=bitcoin]

see also [[Bitcoin Payment Apps]]

===Operating systems===
*[[BAMT]]
*[[LinuxCoin]] - a lightweight Debian-based OS, with the Bitcoin client and GPU mining software

===Mining apps===
Main page: [[Mining software]]
*[[50Miner]] - A GUI frontend for Windows(Poclbm, Phoenix, DiabloMiner, cgminer)
*[[BFGMiner]] - Modular FPGA/GPU miner in C
*[[BTCMiner]] - Bitcoin Miner for ZTEX FPGA Boards
*[[Bit Moose]] - Run Miners as a Windows Service.
*[[Poclbm]] - Python/OpenCL GPU miner ([[Poclbm-gui|GUI(Windows & MacOS X)]])
*[[Poclbm-mod]] - more efficient version of [[Poclbm]] ([[Poclbm-mod-gui|GUI]])
*[[DiabloMiner]] - Java/OpenCL GPU miner ([[DiabloMiner.app|MAC OS X GUI]])
*[[RPC Miner]] - remote RPC miner ([[RPCminer.app|MAC OS X GUI]])
*[[Phoenix miner]] - miner
*[[Cpu Miner]] - miner
*[[Ufasoft miner]] - miner
*[[Pyminer]] - Python miner, reference implementation
*[[Remote miner]] - mining pool software
*[[Open Source FGPA Bitcoin Miner]] - a miner that makes use of an FPGA Board
*[https://github.com/mkburza/Flash-Player-Bitcoin-Miner Flash Player Bitcoin Miner] - A proof of concept Adobe Flash Player miner

===Mining Pool Servers (backend)===
Main page: [[Poolservers]]

*[[ecoinpool]] - Erlang poolserver
*[[Eloipool]] - Fast Python3 poolserver
*[[Pushpoold]] - Old mining poolserver in C (not maintained)
*[[Poold]] - Old Python mining poolserver (not maintained)
*[[PoolServerJ]] - Java mining poolserver (not maintained)

===Utilities, libraries, and interfaces:===
*[[BitcoinCrypto]] - a lightweight Bitcoin crypto library for Java/Android
*[[Bitcoin Dissector]] - a wireshark dissector for the bitcoin protocol
*[[Bitcointools]] - a set of Python tools accessing the transaction database and the wallet
*[[Finance::MtGox]] - a Perl module which interfaces with the Mt. Gox API
*[[libblkmaker]] - C library implementation of [[getblocktemplate]] decentralized mining protocol
*[[python-blkmaker]] - Python module implementation of [[getblocktemplate]] decentralized mining protocol

===Lists of software===
*[[BitGit]] - list of Bitcoin-related opensource projects hosted at Git

===Developer resources===
*[[:Category:Developer|Category:Developer]]
*[[:Category:Technical|Category:Technical]]
*[[Original Bitcoin client/API calls list]]
*[[API reference (JSON-RPC)]]
*[[PHP_developer_intro|PHP Developer Introduction]]

===Other===
*[[Namecoin]] - a distributed naming system based on Bitcoin technology
*[[Bitcoin Consultancy]] - an organization providing open source software and Bitcoin-related consulting
*[[Open Transactions]] - a financial crypto and digital cash software library, complementary to Bitcoin
*[[Moneychanger]] - Java-based GUI for [[Open Transactions]]
*[http://btcnames.org/ BTCnames] - a webbased aliasing service which allows to handle unlimited names for your BTC deposit hashes
*[[Devcoin]] - the open source developer coin

MultiBit

2013-03-25T04:10:58Z

Alvox: Update screenshot, add more external links

[[Image:MultiBit_0.4.23_screenshot_WinXP.png|right|800px|screenshot of Multibit with its Windows XP GUI and Metal theme]]
[http://multibit.org MultiBit] is a lightweight "[[Thin Client Security|thin client]]" Bitcoin wallet for Windows, MacOS and Linux based on [[BitCoinJ]]. Its main advantages over the [[Bitcoin-Qt#Criticism|original Bitcoin client]] include support for opening multiple wallets simultaneously, and not requiring the download of the entire multi-gigabyte [[block chain]] (2.6GB as of July 2012<ref>[http://bitcoin.stackexchange.com/questions/4115/how-big-is-the-blockchain-on-disk-as-of-5th-july-2012 How big is the blockchain on disk as of 5th July 2012?]</ref>). The project is lead by UK developer Jim Burton.<ref>[http://www.youtube.com/watch?v=MnkssdmlaWw European Bitcoin Conference 2012 - Jim Burton - Multibit]</ref>

==Features==
* Multiple wallets can be open at the same time
* Synchronizes with the network in minutes
* Shows the last BTC <--> USD rate from [[MtGox]], [[VirtEx]] and other exchanges
* Import and export your private keys
* Chart of your balance over the last 30 days
* Free and open source (MIT license)
* Localized in a variety of languages

==History==
MultiBit was announced on September 12, 2011.<ref>[http://bitcointalk.org/index.php?topic=43616.0 MultiBit]</ref>

==See Also==
* [[Thin Client Security]]

==External Links==
* [http://multibit.org MultiBit] project website
* [https://github.com/jim618/multibit GitHub repo]
* [https://groups.google.com/forum/?fromgroups=#!forum/bitcoin-multibit Google Group]
* [http://www.youtube.com/user/MultiBitOrg YouTube channel] with "getting started" screencast

==References==
<references />

[[Category:Clients]]
[[Category:Open Source]]

File:MultiBit 0.4.23 screenshot WinXP.png

2013-03-25T03:52:21Z

Alvox: Alvox uploaded a new version of "File:MultiBit 0.4.23 screenshot WinXP.png": Added two other wallets to show the multi-wallet feature

== Summary ==
Screenshot of MultiBit 0.4.23 on Windows XP
== Licensing ==
{{self|Cc-zero}}

File:MultiBit 0.4.23 screenshot WinXP.png

2013-03-25T03:49:27Z

Alvox: Screenshot of MultiBit 0.4.23 on Windows XP

== Summary ==
Screenshot of MultiBit 0.4.23 on Windows XP
== Licensing ==
{{self|Cc-zero}}

MultiBit

2013-03-25T03:43:24Z

Alvox: Better page altogether

[[Image:YourWallets.png|right|600px|screenshot of Multibit with its MacOS GUI]]
[http://multibit.org MultiBit] is a secure, lightweight, international Bitcoin wallet for Windows, MacOS and Linux based on [[BitCoinJ]]. Its main advantages over the [[Bitcoin-Qt#Criticism|original Bitcoin client]] include support for opening multiple wallets simultaneously and not requiring the download of the entire Blockchain. The project is lead by UK developer Jim Burton.<ref>[http://www.youtube.com/watch?v=MnkssdmlaWw European Bitcoin Conference 2012 - Jim Burton - Multibit]</ref>

==Features==
* Multiple wallets can be open at the same time
* Synchronizes with the network in minutes
* Shows the last BTC <--> USD rate from [[MtGox]], [[VirtEx]] and other exchanges
* Import and export your private keys
* Chart of your balance over the last 30 days
* Free and open source (MIT license)
* Localized in a variety of languages

==History==
MultiBit was announced on September 12, 2011.<ref>[http://bitcointalk.org/index.php?topic=43616.0 MultiBit]</ref>

==See Also==
* [[Thin Client Security]]

==External Links==
* [http://multibit.org MultiBit] project website
* [http://www.youtube.com/user/MultiBitOrg YouTube channel] with "getting started" screencast

==References==
<references />

[[Category:Clients]]
[[Category:Open Source]]

Bitcoin Core

2013-03-25T03:29:19Z

Alvox: /* Criticism */ Add criticism of the wallet handling

'''Bitcoin-Qt''' is the third [[Bitcoin]] client, developed by [[Wladimir J. van der Laan]] based on the original reference code by [[Satoshi Nakamoto]].<ref name="Bitcoin Client Software">{{cite web|title=Bitcoin Client Software|url=http://bitcoin.org/clients.html|publisher=Bitcoin.org|accessdate=21 October 2012|quote=The original software written by Satoshi Nakamoto, the project's founder.}}</ref><ref>http://gavintech.blogspot.co.uk/2012/03/full-disclosure-bitcoin-qt-on-windows.html, Full disclosure: Bitcoin-Qt on Windows vulnerability, 21st October 2012</ref><ref>http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2012-4682, Vulnerability Summary for CVE-2012-4682, 21st October 2012</ref> It has been bundled with [[bitcoind]] since version 0.5.<ref name="Bitcoin-Qt/Bitcoind Releases">{{cite web|title=Bitcoin-Qt/Bitcoind Releases|url=http://bitcoin.org/news.html|publisher=Bitcoin.org|accessdate=21 October 2012}}</ref>

==History==

Bitcoin-Qt can used as a desktop client for regular payments or as a server utility for merchants and other payment services.

===Current version===
Source code (and build instructions for supported platforms) can be found at the [https://github.com/bitcoin/bitcoin Bitcoin GitHub page].

==Features==
* Compatibility with Linux (both GNOME and KDE), Mac OS X and Windows
* All functionality of the original wxWidgets client
* Asks for confirmation before sending coins
* CSV export of transactions
* Clearer transaction list with status icons and real-time filtering
* Progress bar on initial block download
* Languages: Dutch, English, German, many more
* Sendmany support in UI (send to multiple recipients in one transaction)
* Multiple [[Units|unit]] support, can show subdivided bitcoins (mBTC, µBTC) for users that like large numbers (only decimal units)
* Splash screen that details progress

==Criticism==
Bitcoin-Qt is often criticized for being slow in downloading and verifying the Bitcoin transaction database (often called the Blockchain).

Wallet management is also cumbersome. Unlike clients such as [[MultiBit]], only one wallet at a time is supported, and its location is hardcoded, making it [[Securing_your_wallet#Making_a_secure_workspace|difficult to place the wallet on an encrypted drive]].

==External Links==

* [https://bitcointalk.org/index.php?topic=15276.0 Forum thread] (includes screenshots)
* [https://github.com/bitcoin/bitcoin Current GitHub repository shared with bitcoind]

<references

/>

==See also==

* [[QBitcoin]]
* [[bitcoind]]

[[es:Bitcoin-Qt]]

[[Category:User Interfaces]]
[[Category:Frontends]]
[[Category:Free Software]]
[[Category:Open Source]]