Blockstream Green

2015-03-19T19:41:19Z

Gurnec: /* Wallet Features */ Be a bit more clear regarding 2-of-2 (the GreenAddress default) vs. 2-of-3 accounts.

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==Wallet Features==

* Open source clients for both desktop and mobile
* [[Deterministic wallet | HD]]/BIP0032
* Per-transaction 2FA via [[multisignature]], of 4 different kinds: email, sms, robot call, Google Authenticator
* 2-of-2 [[multisignature|multisig]] accounts: Create accounts that can take advantage of GreenAddress' trusted-third-party instant confirmations. Account recovery without access to GreenAddress is achieved with pre-generated [[nLockTime]] transactions (which must be received, typically via email, from GreenAddress on a regular basis).
* 2-of-3 [[multisignature|multisig]] accounts: Create accounts that allow you to access your funds at any time even without access to GreenAddress, using an additional offline recovery key (which only needs to be saved once).
* Transaction information within 2FA message
* BIP0039 mnemonics
* Receive or Send/Tip password protected Bitcoins with BIP0038 (Facebook, Email, Reddit)
* Never reuses the same address which improves both privacy and security
* Easy to use, fast and convenient

==More==

* Great customer support, fast turn around via email, twitter, facebook or reddit

* No practice of any reserve mechanism

* testnet/uat service

* GreenAddress' can't take your funds

* detailed transaction logging, real-time on-screen alerts as funds are received

====Links====

* [http://www.expresscoin.com/wallets/bitcoin/greenaddress How to Setup a GreenAddress Bitcoin Wallet]

* [https://play.google.com/store/apps/details?id=it.greenaddress.cordova Android Google Play]

* [https://f-droid.org/repository/browse/?fdfilter=greenaddress&fdid=it.greenaddress.cordova F-Droid Open Source Repo]

* [https://itunes.apple.com/us/app/greenaddress/id889740745 iTunes App Store for iOS]

* [https://chrome.google.com/webstore/detail/greenaddressit/dgbimgjoijjemhdamicmljbncacfndmp Chrome Store]

* [https://github.com/greenaddress/WalletCrx/archive/master.zip Chrome zip for Github (developer mode necessary)]

* [https://greenaddress.it Home]

* [http://blog.greenaddress.it Blog]

* [https://greenaddress.it/faq FAQ]

* [https://greenaddress.it/about About]

* [https://www.youtube.com/watch?v=4PsRUT5oTVU Infographics]

* [https://github.com/greenaddress/ Github]

* [https://reddit.com/r/greenaddress Reddit]

* [https://www.facebook.com/GreenAddressIT Faceboook]

* [https://twitter.com/GreenAddress Twitter]

* [https://test.greenaddress.it Testnet]

[[Category:Wallets]]
[[Category:EWallets]]
[[Category:HybridEWallets]]
[[Category:Services]]
[[Category:Frontends]]
[[Category:Clients]]
[[Category:Mobile]]
[[Category:Cryptobanks]]
[[Category:Bitcoin payment systems]]

Multi-signature

2015-03-19T19:29:44Z

Gurnec: /* Implementations */ Correct the description of GreenAddress.it multisig accounts

Multisigniture (multisig) refers to requiring more than one key to authorize a Bitcoin [[transaction]].

Consider the following scenario:<blockquote>Suppose I am working with a company that wants to accept Bitcoin for international trades.

The company, for security reasons, would not want a single one of its employees to have access to the company BTC wallet's password. Any transaction would have to meet the approval of more than one employee.

Is this possible already? If not, how could it be implemented with public-key cryptography?<ref>https://bitcointalk.org/index.php?topic=507297.msg5594085</ref></blockquote>Multisig is the the solution to this.

==Implementations==
Shamir's [https://en.wikipedia.org/wiki/Secret_sharing Secret Sharing] Scheme (ssss)<ref>https://point-at-infinity.org/ssss/</ref> is a general software implementation of multisig.

Specific to Bitcoin, [[GreenAddress|GreenAddress.it]] has 2-of-2 and 2-of-3 accounts (requiring at least two keys to authorize a transaction). [[Coinbase (business)|Coinbase]] also offers 2-of-3 and 3-of-5 multisig, which they call [https://support.coinbase.com/customer/portal/articles/1743782-what-is-the-multisig-vault- Vault].

==Multisigniture Addresses==
<blockquote>A [[Address#Multi-signature_addresses|multi-signature address]] is an address that is associated with more than one ECDSA private key. The simplest type is an m-of-n address - it is associated with n private keys, and sending bitcoins from this address requires signatures from at least m keys. A multi-signature transaction is one that sends funds from a multi-signature address.<ref>https://bitcoin.stackexchange.com/a/3729/4334</ref></blockquote>
===Creating a Multisigniture Address===
A 2of3 multisig address can be created by following these steps:<ref>https://bitcoin.stackexchange.com/a/10593/4334</ref>

<blockquote><ol><li>Gather (or generate) 3 bitcoin addresses, on whichever machines will be participating, using getnewaddress or getaccountaddress RPC commands (or copy and paste from the GUI).</li>
<li>Get their public keys using the <tt>validateaddress</tt> [[API_reference_%28JSON-RPC%29|RPC]] command 3 times.</li>
<li>Then create a 2-of-3 multisig address using addmultisigaddress; e.g.<blockquote><code>bitcoind addmultisigaddress 2 '["044322868cb17d64dcc22185ae2d4493111d73244c3668f8ac79ecc79c0ba8d30a6756d0fa20157 709af3281cc721c7f53321a8cabda29b77900b7e4fe0174b114","..second pubkey..","..third pubkey.."]'</code></blockquote></li></ol><tt>addmultisigaddress</tt> returns the multisignature address. Be a little careful, the public keys are raw hexadecimal and don't contain checksums like bitcoin addresses do. You can then send funds into that 2-of-3 transaction using the normal sendtoaddress/sendmany RPC commands, or the GUI (or anything that's been updated to recognize multisig addresses).<ref>https://bitcointalk.org/index.php?topic=82213.msg906833#msg906833</ref></blockquote>

==History of Multisigniture==
Multisigniture has been used for thousands of years to protect the security of crypts holding precious relics of saints. The superior of a monastery would give monks only partial "keys" for gaining access to the precious relics; the monks would not know they only held a partial key. Thus, no single monk could gain access to and possibly steal the precious relics.

==References==
<references />

Bitcoin Wiki - User contributions [en]

Blockstream Green

Multi-signature