Function EvalTapScriptCheckSigFromStack

src/script/interpreter.cpp:478–517

}

static bool EvalTapScriptCheckSigFromStack(const valtype& sig, const valtype& vchPubKey, ScriptExecutionData& execdata, unsigned int flags, const valtype& msg, SigVersion sigversion, ScriptError* serror, bool& success)
{
    // This code follows the behaviour of EvalCheckSigTapscript
    assert(sigversion == SigVersion::TAPSCRIPT);

    /*
     *  The following validation sequence is consensus critical. Please note how --
     *    upgradable public key versions precede other rules;
     *    the script execution fails when using empty signature with invalid public key;
     *    the script execution fails when using non-empty invalid signature.
     */
    success = !sig.empty();
    if (success) {
        // Implement the sigops/witnesssize ratio test.
        // Passing with an upgradable public key version is also counted.
        if (!update_validation_weight(execdata, serror)) return false; // serror is set
    }
    if (vchPubKey.size() == 0) {
        return set_error(serror, SCRIPT_ERR_PUBKEYTYPE);
    } else if (vchPubKey.size() == 32) {
        if (success) {
            if (sig.size() != 64)
                return set_error(serror, SCRIPT_ERR_SCHNORR_SIG_SIZE);
            const XOnlyPubKey pubkey{vchPubKey};
            if (!pubkey.VerifySchnorr(msg, sig))
                return set_error(serror, SCRIPT_ERR_SCHNORR_SIG);
        }
    } else {
        /*
         *  New public key version softforks should be defined before this `else` block.
         *  Generally, the new code should not do anything but failing the script execution. To avoid
         *  consensus bugs, it should not modify any existing values (including `success`).
         */
        if ((flags & SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE) != 0) {
            return set_error(serror, SCRIPT_ERR_DISCOURAGE_UPGRADABLE_PUBKEYTYPE);
        }
    }

    return true;
}

static bool EvalChecksigTapscript(const valtype& sig, const valtype& pubkey, ScriptExecutionData& execdata, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* serror, bool& success)
{