Merge pull request bitcoin#620 from satoshilabs/master

BIP 84: Derivation scheme for P2WPKH based accounts

Author: luke-jr

README.mediawiki

@@ -407,6 +407,13 @@ Those proposing changes should consider that ultimately consent may rest with th
 | Standard
 | Draft
 |-
+| [[bip-0084.mediawiki|84]]
+| Applications
+| Derivation scheme for P2WPKH based accounts
+| Pavol Rusnak
+| Informational
+| Draft
+|-
 | [[bip-0090.mediawiki|90]]
 | Consensus (hard fork)
 | Buried Deployments

bip-0084.mediawiki

@@ -0,0 +1,90 @@
+<pre>
+  BIP: 84
+  Layer: Applications
+  Title: Derivation scheme for P2WPKH based accounts
+  Author: Pavol Rusnak <[email protected]>
+  Comments-Summary: No comments yet.
+  Comments-URI: https://github.com/bitcoin/bips/wiki/Comments:BIP-0084
+  Status: Draft
+  Type: Informational
+  Created: 2017-12-28
+  License: CC0-1.0
+</pre>
+
+==Abstract==
+
+This BIP defines the derivation scheme for HD wallets using the P2WPKH ([[bip-0173.mediawiki|BIP 173]]) serialization format for segregated witness transactions.
+
+==Motivation==
+
+With the usage of P2WPKH transactions it is necessary to have a common derivation scheme.
+It allows the user to use different HD wallets with the same masterseed and/or a single account seamlessly.
+
+Thus the user needs to create dedicated segregated witness accounts, which ensures that only wallets compatible with this BIP will detect the accounts and handle them appropriately.
+
+===Considerations===
+
+We use the same rationale as described in Considerations section of [[bip-0049.mediawiki|BIP 49]].
+
+==Specifications==
+
+This BIP defines the two needed steps to derive multiple deterministic addresses based on a [[bip-0032.mediawiki|BIP 32]] root account.
+
+===Public key derivation===
+
+To derive a public key from the root account, this BIP uses the same account-structure as defined in [[bip-0044.mediawiki|BIP 44]] and [[bip-0049.mediawiki|BIP 49]], but only uses a different purpose value to indicate the different transaction serialization method.
+
+<pre>
+m / purpose' / coin_type' / account' / change / address_index
+</pre>
+
+For the <code>purpose</code>-path level it uses <code>84'</code>. The rest of the levels are used as defined in BIP44 or BIP49.
+
+
+===Address derivation===
+
+To derive the P2WPKH address from the above calculated public key, we use the encapsulation defined in [[bip-0141.mediawiki#p2wpkh|BIP 141]]:
+
+
+    witness:      <signature> <pubkey>
+    scriptSig:    (empty)
+    scriptPubKey: 0 <20-byte-key-hash>
+                  (0x0014{20-byte-key-hash})
+
+==Backwards Compatibility==
+
+This BIP is not backwards compatible by design as described under [#considerations]. An incompatible wallet will not discover accounts at all and the user will notice that something is wrong.
+
+==Test vectors==
+
+<pre>
+  mnemonic = abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon abandon about
+  rootnode = zprvAWgYBBk7JR8Gjrh4UJQ2uJdG1r3WNRRfURiABBE3RvMXYSrRJL62XuezvGdPvG6GFBZduosCc1YP5wixPox7zhZLfiUm8aunE96BBa4Kei5
+
+  // Account 0, root = m/84'/0'/0'
+  xpriv = zprvAdG4iTXWBoARxkkzNpNh8r6Qag3irQB8PzEMkAFeTRXxHpbF9z4QgEvBRmfvqWvGp42t42nvgGpNgYSJA9iefm1yYNZKEm7z6qUWCroSQnE
+
+  // Account 0, first receiving address = m/84'/0'/0'/0/0
+  privkey = KyZpNDKnfs94vbrwhJneDi77V6jF64PWPF8x5cdJb8ifgg2DUc9d
+  pubkey  = 0330d54fd0dd420a6e5f8d3624f5f3482cae350f79d5f0753bf5beef9c2d91af3c
+  address = bc1qcr8te4kr609gcawutmrza0j4xv80jy8z306fyu
+
+  // Account 0, second receiving address = m/84'/0'/0'/0/1
+  privkey = Kxpf5b8p3qX56DKEe5NqWbNUP9MnqoRFzZwHRtsFqhzuvUJsYZCy
+  pubkey  = 03e775fd51f0dfb8cd865d9ff1cca2a158cf651fe997fdc9fee9c1d3b5e995ea77
+  address = bc1qnjg0jd8228aq7egyzacy8cys3knf9xvrerkf9g
+
+  // Account 0, first change address = m/84'/0'/0'/1/0
+  privkey = KxuoxufJL5csa1Wieb2kp29VNdn92Us8CoaUG3aGtPtcF3AzeXvF
+  pubkey  = 03025324888e429ab8e3dbaf1f7802648b9cd01e9b418485c5fa4c1b9b5700e1a6
+  address = bc1q8c6fshw2dlwun7ekn9qwf37cu2rn755upcp6el
+</pre>
+
+==Reference==
+
+* [[bip-0032.mediawiki|BIP32 - Hierarchical Deterministic Wallets]]
+* [[bip-0043.mediawiki|BIP43 - Purpose Field for Deterministic Wallets]]
+* [[bip-0044.mediawiki|BIP44 - Multi-Account Hierarchy for Deterministic Wallets]]
+* [[bip-0049.mediawiki|BIP49 - Derivation scheme for P2WPKH-nested-in-P2SH based accounts]]
+* [[bip-0141.mediawiki|BIP141 - Segregated Witness (Consensus layer)]]
+* [[bip-0173.mediawiki|BIP173 - Base32 address format for native v0-16 witness outputs]]