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txscript: Introduce calcWitnessSignatureHashRaw

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Conner Fromknecht 2019-04-19 15:25:18 -07:00 committed by Olaoluwa Osuntokun
parent 7ad3a10442
commit dd609d6e36
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GPG key ID: 3BBD59E99B280306
1 changed files with 29 additions and 6 deletions
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35
txscript/script.go
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@ -385,7 +385,7 @@ func calcHashOutputs(tx *wire.MsgTx) chainhash.Hash {
return chainhash.DoubleHashH(b.Bytes()) return chainhash.DoubleHashH(b.Bytes())
} }
// calcWitnessSignatureHash computes the sighash digest of a transaction's // calcWitnessSignatureHashRaw computes the sighash digest of a transaction's
// segwit input using the new, optimized digest calculation algorithm defined // segwit input using the new, optimized digest calculation algorithm defined
// in BIP0143: https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki. // in BIP0143: https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki.
// This function makes use of pre-calculated sighash fragments stored within // This function makes use of pre-calculated sighash fragments stored within
@ -396,7 +396,7 @@ func calcHashOutputs(tx *wire.MsgTx) chainhash.Hash {
// being spent, in addition to the final transaction fee. In the case the // being spent, in addition to the final transaction fee. In the case the
// wallet if fed an invalid input amount, the real sighash will differ causing // wallet if fed an invalid input amount, the real sighash will differ causing
// the produced signature to be invalid. // the produced signature to be invalid.
func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes, func calcWitnessSignatureHashRaw(scriptSig []byte, sigHashes *TxSigHashes,
hashType SigHashType, tx *wire.MsgTx, idx int, amt int64) ([]byte, error) { hashType SigHashType, tx *wire.MsgTx, idx int, amt int64) ([]byte, error) {
// As a sanity check, ensure the passed input index for the transaction // As a sanity check, ensure the passed input index for the transaction
@ -446,7 +446,7 @@ func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
binary.LittleEndian.PutUint32(bIndex[:], txIn.PreviousOutPoint.Index) binary.LittleEndian.PutUint32(bIndex[:], txIn.PreviousOutPoint.Index)
sigHash.Write(bIndex[:]) sigHash.Write(bIndex[:])
if isWitnessPubKeyHash(subScript) { if isWitnessPubKeyHashScript(scriptSig) {
// The script code for a p2wkh is a length prefix varint for // The script code for a p2wkh is a length prefix varint for
// the next 25 bytes, followed by a re-creation of the original // the next 25 bytes, followed by a re-creation of the original
// p2pkh pk script. // p2pkh pk script.
@ -454,15 +454,14 @@ func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
sigHash.Write([]byte{OP_DUP}) sigHash.Write([]byte{OP_DUP})
sigHash.Write([]byte{OP_HASH160}) sigHash.Write([]byte{OP_HASH160})
sigHash.Write([]byte{OP_DATA_20}) sigHash.Write([]byte{OP_DATA_20})
sigHash.Write(subScript[1].data) sigHash.Write(extractWitnessPubKeyHash(scriptSig))
sigHash.Write([]byte{OP_EQUALVERIFY}) sigHash.Write([]byte{OP_EQUALVERIFY})
sigHash.Write([]byte{OP_CHECKSIG}) sigHash.Write([]byte{OP_CHECKSIG})
} else { } else {
// For p2wsh outputs, and future outputs, the script code is // For p2wsh outputs, and future outputs, the script code is
// the original script, with all code separators removed, // the original script, with all code separators removed,
// serialized with a var int length prefix. // serialized with a var int length prefix.
rawScript, _ := unparseScript(subScript) wire.WriteVarBytes(&sigHash, 0, scriptSig)
wire.WriteVarBytes(&sigHash, 0, rawScript)
} }
// Next, add the input amount, and sequence number of the input being // Next, add the input amount, and sequence number of the input being
@ -501,6 +500,30 @@ func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
return chainhash.DoubleHashB(sigHash.Bytes()), nil return chainhash.DoubleHashB(sigHash.Bytes()), nil
} }
// calcWitnessSignatureHash computes the sighash digest of a transaction's
// segwit input using the new, optimized digest calculation algorithm defined
// in BIP0143: https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki.
// This function makes use of pre-calculated sighash fragments stored within
// the passed HashCache to eliminate duplicate hashing computations when
// calculating the final digest, reducing the complexity from O(N^2) to O(N).
// Additionally, signatures now cover the input value of the referenced unspent
// output. This allows offline, or hardware wallets to compute the exact amount
// being spent, in addition to the final transaction fee. In the case the
// wallet if fed an invalid input amount, the real sighash will differ causing
// the produced signature to be invalid.
//
// DEPRECATED: Use calcWitnessSignatureHashRaw instead.
func calcWitnessSignatureHash(subScript []parsedOpcode, sigHashes *TxSigHashes,
hashType SigHashType, tx *wire.MsgTx, idx int, amt int64) ([]byte, error) {
script, err := unparseScript(subScript)
if err != nil {
return nil, err
}
return calcWitnessSignatureHashRaw(script, sigHashes, hashType, tx, idx, amt)
}
// CalcWitnessSigHash computes the sighash digest for the specified input of // CalcWitnessSigHash computes the sighash digest for the specified input of
// the target transaction observing the desired sig hash type. // the target transaction observing the desired sig hash type.
func CalcWitnessSigHash(script []byte, sigHashes *TxSigHashes, hType SigHashType, func CalcWitnessSigHash(script []byte, sigHashes *TxSigHashes, hType SigHashType,