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Diffstat (limited to 'bip-0141.mediawiki')
| -rw-r--r-- | bip-0141.mediawiki | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/bip-0141.mediawiki b/bip-0141.mediawiki index efdd9c9..117ca59 100644 --- a/bip-0141.mediawiki +++ b/bip-0141.mediawiki @@ -83,19 +83,23 @@ If all transactions in a block do not have witness data, the commitment is optio === Witness program === -A <code>scriptPubKey</code> (or <code>redeemScript</code> as defined in BIP16/P2SH) that consists of a 1-byte push opcode (for 0 to 16) followed by a data push between 2 and 40 bytes gets a new special meaning. The value of the first push is called the "version byte". The following byte vector pushed is called the "witness program". +A <code>scriptPubKey</code> (or <code>redeemScript</code> as defined in BIP16/P2SH) that consists of a 1-byte push opcode (one of <code>OP_0,OP_1,OP_2,...,OP_16</code>) followed by a direct data push between 2 and 40 bytes gets a new special meaning. The value of the first push is called the "version byte". The following byte vector pushed is called the "witness program". +In more detail, this means a <code>scriptPubKey</code> or <code>redeemScript</code> which consists of (in order): +* First, byte 0x00 (<code>OP_0</code>) or any byte between 0x51 (<code>OP_1</code>) and 0x60 (<code>OP_16</code>) inclusive (the version byte). +* Then, a byte ''L'' between 0x02 (push of 2 bytes) and 0x28 (push of 40 bytes) inclusive. +* Finally, ''L'' arbitrary bytes (the witness program). There are two cases in which witness validation logic are triggered. Each case determines the location of the witness version byte and program, as well as the form of the scriptSig: # Triggered by a <code>scriptPubKey</code> that is exactly a push of a version byte, plus a push of a witness program. The scriptSig must be exactly empty or validation fails. (''"native witness program"'') # Triggered when a <code>scriptPubKey</code> is a P2SH script, and the BIP16 <code>redeemScript</code> pushed in the <code>scriptSig</code> is exactly a push of a version byte plus a push of a witness program. The <code>scriptSig</code> must be exactly a push of the BIP16 <code>redeemScript</code> or validation fails. (''"P2SH witness program"'') -If the version byte is 0, and the witness program is 20 bytes: +If the version byte is 0, and the witness program is 20 bytes (''L = 20''): * It is interpreted as a pay-to-witness-public-key-hash (P2WPKH) program. * The witness must consist of exactly 2 items (≤ 520 bytes each). The first one a signature, and the second one a public key. * The HASH160 of the public key must match the 20-byte witness program. * After normal script evaluation, the signature is verified against the public key with CHECKSIG operation. The verification must result in a single TRUE on the stack. -If the version byte is 0, and the witness program is 32 bytes: +If the version byte is 0, and the witness program is 32 bytes (''L = 32''): * It is interpreted as a pay-to-witness-script-hash (P2WSH) program. * The witness must consist of an input stack to feed to the script, followed by a serialized script (<code>witnessScript</code>). * The <code>witnessScript</code> (≤ 10,000 bytes) is popped off the initial witness stack. SHA256 of the <code>witnessScript</code> must match the 32-byte witness program. @@ -276,7 +280,7 @@ These commitments could be included in the extensible commitment structure throu Since a version byte is pushed before a witness program, and programs with unknown versions are always considered as anyone-can-spend script, it is possible to introduce any new script system with a soft fork. The witness as a structure is not restricted by any existing script semantics and constraints, the 520-byte push limit in particular, and therefore allows arbitrarily large scripts and signatures. -Examples of new script system include Schnorr signatures which reduce the size of multisig transactions dramatically, Lamport signature which is quantum computing resistance, and Merklized abstract syntax trees which allow very compact witness for conditional scripts with extreme complexity. +Examples of new script systems include Schnorr signatures, which reduce the size of multisig transactions dramatically; Lamport signatures, which are quantum computing resistant; and Merklized abstract syntax trees, which allow very compact witnesses for conditional scripts with extreme complexity. === Per-input lock-time and relative-lock-time === @@ -303,7 +307,7 @@ As a soft fork, older software will continue to operate without modification. N This BIP will be deployed by "version bits" BIP9 with the name "segwit" and using bit 1. -For Bitcoin mainnet, the BIP9 starttime will be midnight 15 november 2016 UTC (Epoch timestamp 1479168000) and BIP9 timeout will be midnight 15 november 2017 UTC (Epoch timestamp 1510704000). +For Bitcoin mainnet, the BIP9 starttime will be midnight 15 November 2016 UTC (Epoch timestamp 1479168000) and BIP9 timeout will be midnight 15 November 2017 UTC (Epoch timestamp 1510704000). For Bitcoin testnet, the BIP9 starttime will be midnight 1 May 2016 UTC (Epoch timestamp 1462060800) and BIP9 timeout will be midnight 1 May 2017 UTC (Epoch timestamp 1493596800). |