Method CreateMuSig2PartialSig

src/script/sign.cpp:145–189

}

bool MutableTransactionSignatureCreator::CreateMuSig2PartialSig(const SigningProvider& provider, uint256& partial_sig, const CPubKey& aggregate_pubkey, const CPubKey& script_pubkey, const CPubKey& part_pubkey, const uint256* leaf_hash, const std::vector<std::pair<uint256, bool>>& tweaks, SigVersion sigversion, const SignatureData& sigdata) const
{
    assert(sigversion == SigVersion::TAPROOT || sigversion == SigVersion::TAPSCRIPT);

    // Retrieve private key
    CKey key;
    if (!provider.GetKey(part_pubkey.GetID(), key)) return false;

    // Retrieve participant pubkeys
    auto it = sigdata.musig2_pubkeys.find(aggregate_pubkey);
    if (it == sigdata.musig2_pubkeys.end()) return false;
    const std::vector<CPubKey>& pubkeys = it->second;
    if (std::find(pubkeys.begin(), pubkeys.end(), part_pubkey) == pubkeys.end()) return {};

    // Retrieve pubnonces
    auto this_leaf_aggkey = std::make_pair(script_pubkey, leaf_hash ? *leaf_hash : uint256());
    auto pubnonce_it = sigdata.musig2_pubnonces.find(this_leaf_aggkey);
    if (pubnonce_it == sigdata.musig2_pubnonces.end()) return false;
    const std::map<CPubKey, std::vector<uint8_t>>& pubnonces = pubnonce_it->second;

    // Check if enough pubnonces
    if (pubnonces.size() != pubkeys.size()) return false;

    // Compute sighash
    std::optional<uint256> sighash = ComputeSchnorrSignatureHash(leaf_hash, sigversion);
    if (!sighash.has_value()) return false;

    // Retrieve the secnonce
    auto part_pubnonce_it = pubnonces.find(part_pubkey);
    if (part_pubnonce_it == pubnonces.end()) return false;
    uint256 session_id = MuSig2SessionID(script_pubkey, part_pubkey, *sighash, part_pubnonce_it->second);
    std::optional<std::reference_wrapper<MuSig2SecNonce>> secnonce = provider.GetMuSig2SecNonce(session_id);
    if (!secnonce || !secnonce->get().IsValid()) return false;

    // Compute the sig
    std::optional<uint256> sig = ::CreateMuSig2PartialSig(*sighash, key, aggregate_pubkey, pubkeys, pubnonces, *secnonce, tweaks);
    if (!sig) return false;
    partial_sig = std::move(*sig);

    // Delete the secnonce now that we're done with it
    assert(!secnonce->get().IsValid());
    provider.DeleteMuSig2Session(session_id);

    return true;
}

bool MutableTransactionSignatureCreator::CreateMuSig2AggregateSig(const std::vector<CPubKey>& participants, std::vector<uint8_t>& sig, const CPubKey& aggregate_pubkey, const CPubKey& script_pubkey, const uint256* leaf_hash, const std::vector<std::pair<uint256, bool>>& tweaks, SigVersion sigversion, const SignatureData& sigdata) const
{