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sign: Add CreateMuSig2AggregateSig

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Ava Chow 2024-01-29 17:32:49 -05:00
parent bf69442b3f
commit 258db93889
4 changed files with 125 additions and 0 deletions
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86
src/musig.cpp
View File

@ -118,3 +118,89 @@ uint256 MuSig2SessionID(const CPubKey& script_pubkey, const CPubKey& part_pubkey
hasher << script_pubkey << part_pubkey << sighash;
return hasher.GetSHA256();
}
std::optional<std::vector<uint8_t>> CreateMuSig2AggregateSig(const std::vector<CPubKey>& part_pubkeys, const CPubKey& aggregate_pubkey, const std::vector<std::pair<uint256, bool>>& tweaks, const uint256& sighash, const std::map<CPubKey, std::vector<uint8_t>>& pubnonces, const std::map<CPubKey, uint256>& partial_sigs)
{
if (!part_pubkeys.size()) return std::nullopt;
// Get the keyagg cache and aggregate pubkey
secp256k1_musig_keyagg_cache keyagg_cache;
if (!MuSig2AggregatePubkeys(part_pubkeys, keyagg_cache, aggregate_pubkey)) return std::nullopt;
// Check if enough pubnonces and partial sigs
if (pubnonces.size() != part_pubkeys.size()) return std::nullopt;
if (partial_sigs.size() != part_pubkeys.size()) return std::nullopt;
// Parse the pubnonces and partial sigs
std::vector<std::tuple<secp256k1_pubkey, secp256k1_musig_pubnonce, secp256k1_musig_partial_sig>> signers_data;
std::vector<const secp256k1_musig_pubnonce*> pubnonce_ptrs;
std::vector<const secp256k1_musig_partial_sig*> partial_sig_ptrs;
for (const CPubKey& part_pk : part_pubkeys) {
const auto& pn_it = pubnonces.find(part_pk);
if (pn_it == pubnonces.end()) return std::nullopt;
const std::vector<uint8_t> pubnonce = pn_it->second;
if (pubnonce.size() != MUSIG2_PUBNONCE_SIZE) return std::nullopt;
const auto& it = partial_sigs.find(part_pk);
if (it == partial_sigs.end()) return std::nullopt;
const uint256& partial_sig = it->second;
auto& [secp_pk, secp_pn, secp_ps] = signers_data.emplace_back();
if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &secp_pk, part_pk.data(), part_pk.size())) {
return std::nullopt;
}
if (!secp256k1_musig_pubnonce_parse(secp256k1_context_static, &secp_pn, pubnonce.data())) {
return std::nullopt;
}
if (!secp256k1_musig_partial_sig_parse(secp256k1_context_static, &secp_ps, partial_sig.data())) {
return std::nullopt;
}
}
pubnonce_ptrs.reserve(signers_data.size());
partial_sig_ptrs.reserve(signers_data.size());
for (auto& [_, pn, ps] : signers_data) {
pubnonce_ptrs.push_back(&pn);
partial_sig_ptrs.push_back(&ps);
}
// Aggregate nonces
secp256k1_musig_aggnonce aggnonce;
if (!secp256k1_musig_nonce_agg(secp256k1_context_static, &aggnonce, pubnonce_ptrs.data(), pubnonce_ptrs.size())) {
return std::nullopt;
}
// Apply tweaks
for (const auto& [tweak, xonly] : tweaks) {
if (xonly) {
if (!secp256k1_musig_pubkey_xonly_tweak_add(secp256k1_context_static, nullptr, &keyagg_cache, tweak.data())) {
return std::nullopt;
}
} else if (!secp256k1_musig_pubkey_ec_tweak_add(secp256k1_context_static, nullptr, &keyagg_cache, tweak.data())) {
return std::nullopt;
}
}
// Create musig_session
secp256k1_musig_session session;
if (!secp256k1_musig_nonce_process(secp256k1_context_static, &session, &aggnonce, sighash.data(), &keyagg_cache)) {
return std::nullopt;
}
// Verify partial sigs
for (const auto& [pk, pb, ps] : signers_data) {
if (!secp256k1_musig_partial_sig_verify(secp256k1_context_static, &ps, &pb, &pk, &keyagg_cache, &session)) {
return std::nullopt;
}
}
// Aggregate partial sigs
std::vector<uint8_t> sig;
sig.resize(64);
if (!secp256k1_musig_partial_sig_agg(secp256k1_context_static, sig.data(), &session, partial_sig_ptrs.data(), partial_sig_ptrs.size())) {
return std::nullopt;
}
return sig;
}

2
src/musig.h
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@ -62,4 +62,6 @@ public:
uint256 MuSig2SessionID(const CPubKey& script_pubkey, const CPubKey& part_pubkey, const uint256& sighash);
std::optional<std::vector<uint8_t>> CreateMuSig2AggregateSig(const std::vector<CPubKey>& participants, const CPubKey& aggregate_pubkey, const std::vector<std::pair<uint256, bool>>& tweaks, const uint256& sighash, const std::map<CPubKey, std::vector<uint8_t>>& pubnonces, const std::map<CPubKey, uint256>& partial_sigs);
#endif // BITCOIN_MUSIG_H

35
src/script/sign.cpp
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@ -174,6 +174,36 @@ bool MutableTransactionSignatureCreator::CreateMuSig2PartialSig(const SigningPro
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
{
assert(sigversion == SigVersion::TAPROOT || sigversion == SigVersion::TAPSCRIPT);
if (!participants.size()) return false;
// Retrieve pubnonces and partial sigs
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;
auto partial_sigs_it = sigdata.musig2_partial_sigs.find(this_leaf_aggkey);
if (partial_sigs_it == sigdata.musig2_partial_sigs.end()) return false;
const std::map<CPubKey, uint256>& partial_sigs = partial_sigs_it->second;
// Check if enough pubnonces and partial sigs
if (pubnonces.size() != participants.size()) return false;
if (partial_sigs.size() != participants.size()) return false;
// Compute sighash
std::optional<uint256> sighash = ComputeSchnorrSignatureHash(leaf_hash, sigversion);
if (!sighash.has_value()) return false;
std::optional<std::vector<uint8_t>> res = ::CreateMuSig2AggregateSig(participants, aggregate_pubkey, tweaks, *sighash, pubnonces, partial_sigs);
if (!res) return false;
sig = res.value();
if (nHashType) sig.push_back(nHashType);
return true;
}
static bool GetCScript(const SigningProvider& provider, const SignatureData& sigdata, const CScriptID& scriptid, CScript& script)
{
if (provider.GetCScript(scriptid, script)) {
@ -840,6 +870,11 @@ public:
partial_sig = uint256::ONE;
return true;
}
bool 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 override
{
sig.assign(64, '\000');
return true;
}
};
}

2
src/script/sign.h
View File

@ -36,6 +36,7 @@ public:
virtual bool CreateSchnorrSig(const SigningProvider& provider, std::vector<unsigned char>& sig, const XOnlyPubKey& pubkey, const uint256* leaf_hash, const uint256* merkle_root, SigVersion sigversion) const =0;
virtual std::vector<uint8_t> CreateMuSig2Nonce(const SigningProvider& provider, const CPubKey& aggregate_pubkey, const CPubKey& script_pubkey, const CPubKey& part_pubkey, const uint256* leaf_hash, const uint256* merkle_root, SigVersion sigversion, const SignatureData& sigdata) const =0;
virtual bool 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 =0;
virtual bool 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 =0;
};
/** A signature creator for transactions. */
@ -58,6 +59,7 @@ public:
bool CreateSchnorrSig(const SigningProvider& provider, std::vector<unsigned char>& sig, const XOnlyPubKey& pubkey, const uint256* leaf_hash, const uint256* merkle_root, SigVersion sigversion) const override;
std::vector<uint8_t> CreateMuSig2Nonce(const SigningProvider& provider, const CPubKey& aggregate_pubkey, const CPubKey& script_pubkey, const CPubKey& part_pubkey, const uint256* leaf_hash, const uint256* merkle_root, SigVersion sigversion, const SignatureData& sigdata) const override;
bool 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 override;
bool 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 override;
};
/** A signature checker that accepts all signatures */