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diff --git a/bip-0044.mediawiki b/bip-0044.mediawiki new file mode 100644 index 0000000..df6f8e6 --- /dev/null +++ b/bip-0044.mediawiki @@ -0,0 +1,262 @@ +<pre> + BIP: BIP-0044 + Title: Multi-Account Hierarchy for Deterministic Wallets + Authors: Marek Palatinus <slush@satoshilabs.com> + Pavol Rusnak <stick@satoshilabs.com> + Status: Draft + Type: Standards Track + Created: 2014-04-24 +</pre> + +==Abstract== + +This BIP defines a logical hierarchy for deterministic wallets based on an algorithm +described in BIP-0032 (BIP32 from now on) and purpose scheme described in +BIP-0043 (BIP43 from now on). + +This BIP is a particular application of BIP43. + +==Motivation== + +The hierarchy proposed in this paper is quite comprehensive. It allows the handling of +multiple coins, multiple accounts, external and internal chains per account and +millions of addresses per chain. + +==Path levels== + +We define the following 5 levels in BIP32 path: + +<pre> +m / purpose' / coin_type' / account' / change / address_index +</pre> + +Apostrophe in the path indicates that BIP32 hardened derivation is used. + +Each level has a special meaning, described in the chapters below. + +===Purpose=== + +Purpose is a constant set to 44' (or 0x8000002C) following the BIP43 recommendation. +It indicates that the subtree of this node is used according to this specification. + +Hardened derivation is used at this level. + +===Coin type=== + +One master node (seed) can be used for unlimited number of independent +cryptocoins such as Bitcoin, Litecoin or Namecoin. However, sharing the same +space for various cryptocoins has some disadvantages. + +This level creates a separate subtree for every cryptocoin, avoiding +reusing addresses across cryptocoins and improving privacy issues. + +Coin type is a constant, set for each cryptocoin. Cryptocoin developers may ask +for registering unused number for their project. + +The list of already allocated coin types is in the chapter +"Registered coin types" below. + +Hardened derivation is used at this level. + +===Account=== + +This level splits the key space into independent user identities, +so the wallet never mixes the coins across different accounts. + +Users can use these accounts to organize the funds in the same +fashion as bank accounts; for donation purposes (where all +addresses are considered public), for saving purposes, +for common expenses etc. + +Accounts are numbered from index 0 in sequentially increasing manner. +This number is used as child index in BIP32 derivation. + +Hardened derivation is used at this level. + +Software should prevent a creation of an account if a previous account does not +have a transaction history (meaning none of its addresses have been used before). + +Software needs to discover all used accounts after importing the seed from +an external source. Such an algorithm is described in "Account discovery" chapter. + +===Change=== + +Constant 0 is used for external chain and constant 1 for internal chain (also +known as change addresses). External chain is used for addresses that are meant +to be visible outside of the wallet (e.g. for receiving payments). Internal +chain is used for addresses which are not meant to be visible outside of the +wallet and is used for return transaction change. + +Public derivation is used at this level. + +===Index=== + +Addresses are numbered from index 0 in sequentially increasing manner. +This number is used as child index in BIP32 derivation. + +Public derivation is used at this level. + +==Account discovery== + +When the master seed is imported from an external source the software should +start to discover the accounts in the following manner: + +# derive the first account's node (index = 0) +# derive the external chain node of this account +# scan addresses of the external chain; respect the gap limit described below +# if no transactions are found on the external chain, stop discovery +# if there are some transactions, increase the account index and go to step 1 + +This algorithm is successful because software should disallow creation of new +accounts if previous one has no transaction history, as described in chapter +"Account" above. + +Please note that the algorithm works with the transaction history, not account +balances, so you can have an account with 0 total coins and the algorithm will +still continue with discovery. + +===Address gap limit=== + +Address gap limit is currently set to 20. If the software hits 20 unused +addresses in a row, it expects there are no used addresses beyond this point +and stops searching the address chain. We scan just the external chains, because +internal chains receive only coins that come from the associated external chains. + +Wallet software should warn when the user is trying to exceed the gap limit on +an external chain by generating a new address. + +==Registered coin types== + +These are the registered coin types for usage in level 2 of BIP44 described in +chapter "Coin type" above. + +All these constants are used as hardened derivation. + +{| +!index +!hexa +!coin +|- +|0 +|0x80000000 +|Bitcoin +|- +|1 +|0x80000001 +|Bitcoin Testnet +|} + +==Examples== + +{| +!coin +!account +!chain +!address +!path +|- +|Bitcoin +|first +|external +|first +|m / 44' / 0' / 0' / 0 / 0 +|- +|Bitcoin +|first +|external +|second +|m / 44' / 0' / 0' / 0 / 1 +|- +|Bitcoin +|first +|change +|first +|m / 44' / 0' / 0' / 1 / 0 +|- +|Bitcoin +|first +|change +|second +|m / 44' / 0' / 0' / 1 / 1 +|- +|Bitcoin +|second +|external +|first +|m / 44' / 0' / 1' / 0 / 0 +|- +|Bitcoin +|second +|external +|second +|m / 44' / 0' / 1' / 0 / 1 +|- +|Bitcoin +|second +|change +|first +|m / 44' / 0' / 1' / 1 / 0 +|- +|Bitcoin +|second +|change +|second +|m / 44' / 0' / 1' / 1 / 1 +|- +|Bitcoin Testnet +|first +|external +|first +|m / 44' / 1' / 0' / 0 / 0 +|- +|Bitcoin Testnet +|first +|external +|second +|m / 44' / 1' / 0' / 0 / 1 +|- +|Bitcoin Testnet +|first +|change +|first +|m / 44' / 1' / 0' / 1 / 0 +|- +|Bitcoin Testnet +|first +|change +|second +|m / 44' / 1' / 0' / 1 / 1 +|- +|Bitcoin Testnet +|second +|external +|first +|m / 44' / 1' / 1' / 0 / 0 +|- +|Bitcoin Testnet +|second +|external +|second +|m / 44' / 1' / 1' / 0 / 1 +|- +|Bitcoin Testnet +|second +|change +|first +|m / 44' / 1' / 1' / 1 / 0 +|- +|Bitcoin Testnet +|second +|change +|second +|m / 44' / 1' / 1' / 1 / 1 +|} + +==Compatible wallets== + +* [[https://mytrezor.com|myTREZOR web wallet]] ([[https://github.com/trezor/webwallet|source]]) + +==Reference== + +* [[bip-0032.mediawiki|BIP32 - Hierarchical Deterministic Wallets]] +* [[bip-0043.mediawiki|BIP43 - Purpose Field for Deterministic Wallets]] |