Function SignTaproot

src/script/sign.cpp:186–229

}

static bool SignTaproot(const SigningProvider& provider, const BaseSignatureCreator& creator, const WitnessV1Taproot& output, SignatureData& sigdata, std::vector<valtype>& result)
{
    TaprootSpendData spenddata;

    // Gather information about this output.
    if (provider.GetTaprootSpendData(output, spenddata)) {
        sigdata.tr_spenddata.Merge(spenddata);
    }

    // Try key path spending.
    {
        std::vector<unsigned char> sig;
        if (sigdata.taproot_key_path_sig.size() == 0) {
            if (creator.CreateSchnorrSig(provider, sig, spenddata.internal_key, nullptr, &spenddata.merkle_root, SigVersion::TAPROOT)) {
                sigdata.taproot_key_path_sig = sig;
            }
        }
        if (sigdata.taproot_key_path_sig.size()) {
            result = Vector(sigdata.taproot_key_path_sig);
            return true;
        }
    }

    // Try script path spending.
    std::vector<std::vector<unsigned char>> smallest_result_stack;
    for (const auto& [key, control_blocks] : sigdata.tr_spenddata.scripts) {
        const auto& [script, leaf_ver] = key;
        std::vector<std::vector<unsigned char>> result_stack;
        if (SignTaprootScript(provider, creator, sigdata, leaf_ver, script, result_stack)) {
            result_stack.emplace_back(std::begin(script), std::end(script)); // Push the script
            result_stack.push_back(*control_blocks.begin()); // Push the smallest control block
            if (smallest_result_stack.size() == 0 ||
                GetSerializeSize(result_stack, PROTOCOL_VERSION) < GetSerializeSize(smallest_result_stack, PROTOCOL_VERSION)) {
                smallest_result_stack = std::move(result_stack);
            }
        }
    }
    if (smallest_result_stack.size() != 0) {
        result = std::move(smallest_result_stack);
        return true;
    }

    return false;
}

/**
 * Sign scriptPubKey using signature made with creator.