diff options
| -rw-r--r-- | src/script/interpreter.cpp | 32 | ||||
| -rw-r--r-- | src/script/interpreter.h | 6 |
2 files changed, 28 insertions, 10 deletions
diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp index 2dd173ee20..8cebbc5d10 100644 --- a/src/script/interpreter.cpp +++ b/src/script/interpreter.cpp @@ -1847,16 +1847,14 @@ static bool ExecuteWitnessScript(const Span<const valtype>& stack_span, const CS return true; } -static bool VerifyTaprootCommitment(const std::vector<unsigned char>& control, const std::vector<unsigned char>& program, const CScript& script, uint256& tapleaf_hash) +uint256 ComputeTapleafHash(uint8_t leaf_version, const CScript& script) +{ + return (CHashWriter(HASHER_TAPLEAF) << leaf_version << script).GetSHA256(); +} + +uint256 ComputeTaprootMerkleRoot(Span<const unsigned char> control, const uint256& tapleaf_hash) { const int path_len = (control.size() - TAPROOT_CONTROL_BASE_SIZE) / TAPROOT_CONTROL_NODE_SIZE; - //! The internal pubkey (x-only, so no Y coordinate parity). - const XOnlyPubKey p{uint256(std::vector<unsigned char>(control.begin() + 1, control.begin() + TAPROOT_CONTROL_BASE_SIZE))}; - //! The output pubkey (taken from the scriptPubKey). - const XOnlyPubKey q{uint256(program)}; - // Compute the tapleaf hash. - tapleaf_hash = (CHashWriter(HASHER_TAPLEAF) << uint8_t(control[0] & TAPROOT_LEAF_MASK) << script).GetSHA256(); - // Compute the Merkle root from the leaf and the provided path. uint256 k = tapleaf_hash; for (int i = 0; i < path_len; ++i) { CHashWriter ss_branch{HASHER_TAPBRANCH}; @@ -1868,8 +1866,21 @@ static bool VerifyTaprootCommitment(const std::vector<unsigned char>& control, c } k = ss_branch.GetSHA256(); } + return k; +} + +static bool VerifyTaprootCommitment(const std::vector<unsigned char>& control, const std::vector<unsigned char>& program, const uint256& tapleaf_hash) +{ + assert(control.size() >= TAPROOT_CONTROL_BASE_SIZE); + assert(program.size() >= uint256::size()); + //! The internal pubkey (x-only, so no Y coordinate parity). + const XOnlyPubKey p{uint256(std::vector<unsigned char>(control.begin() + 1, control.begin() + TAPROOT_CONTROL_BASE_SIZE))}; + //! The output pubkey (taken from the scriptPubKey). + const XOnlyPubKey q{uint256(program)}; + // Compute the Merkle root from the leaf and the provided path. + const uint256 merkle_root = ComputeTaprootMerkleRoot(control, tapleaf_hash); // Verify that the output pubkey matches the tweaked internal pubkey, after correcting for parity. - return q.CheckTapTweak(p, k, control[0] & 1); + return q.CheckTapTweak(p, merkle_root, control[0] & 1); } static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion, const std::vector<unsigned char>& program, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror, bool is_p2sh) @@ -1929,7 +1940,8 @@ static bool VerifyWitnessProgram(const CScriptWitness& witness, int witversion, if (control.size() < TAPROOT_CONTROL_BASE_SIZE || control.size() > TAPROOT_CONTROL_MAX_SIZE || ((control.size() - TAPROOT_CONTROL_BASE_SIZE) % TAPROOT_CONTROL_NODE_SIZE) != 0) { return set_error(serror, SCRIPT_ERR_TAPROOT_WRONG_CONTROL_SIZE); } - if (!VerifyTaprootCommitment(control, program, exec_script, execdata.m_tapleaf_hash)) { + execdata.m_tapleaf_hash = ComputeTapleafHash(control[0] & TAPROOT_LEAF_MASK, exec_script); + if (!VerifyTaprootCommitment(control, program, execdata.m_tapleaf_hash)) { return set_error(serror, SCRIPT_ERR_WITNESS_PROGRAM_MISMATCH); } execdata.m_tapleaf_hash_init = true; diff --git a/src/script/interpreter.h b/src/script/interpreter.h index ced5c28bc1..034c937b99 100644 --- a/src/script/interpreter.h +++ b/src/script/interpreter.h @@ -317,6 +317,12 @@ public: } }; +/** Compute the BIP341 tapleaf hash from leaf version & script. */ +uint256 ComputeTapleafHash(uint8_t leaf_version, const CScript& script); +/** Compute the BIP341 taproot script tree Merkle root from control block and leaf hash. + * Requires control block to have valid length (33 + k*32, with k in {0,1,..,128}). */ +uint256 ComputeTaprootMerkleRoot(Span<const unsigned char> control, const uint256& tapleaf_hash); + bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptExecutionData& execdata, ScriptError* error = nullptr); bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* error = nullptr); bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror = nullptr); |