/tmp/bitcoin/src/musig.cpp

Source
// Copyright (c) 2024-present The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#include <musig.h>
#include <key.h>
#include <random.h>
#include <support/allocators/secure.h>

#include <secp256k1_musig.h>

//! MuSig2 chaincode as defined by BIP 328
using namespace util::hex_literals;
const ChainCode MUSIG_CHAINCODE{"868087ca02a6f974c4598924c36b57762d32cb45717167e300622c7167e38965"_hex_u8};

static bool GetMuSig2KeyAggCache(const std::vector<CPubKey>& pubkeys, secp256k1_musig_keyagg_cache& keyagg_cache)
{
    if (pubkeys.empty()) {
        return false;
    }

    // Parse the pubkeys
    std::vector<secp256k1_pubkey> secp_pubkeys;
    std::vector<const secp256k1_pubkey*> pubkey_ptrs;
    for (const CPubKey& pubkey : pubkeys) {
        if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &secp_pubkeys.emplace_back(), pubkey.data(), pubkey.size())) {
            return false;
        }
    }
    pubkey_ptrs.reserve(secp_pubkeys.size());
    for (const secp256k1_pubkey& p : secp_pubkeys) {
        pubkey_ptrs.push_back(&p);
    }

    // Aggregate the pubkey
    if (!secp256k1_musig_pubkey_agg(secp256k1_context_static, nullptr, &keyagg_cache, pubkey_ptrs.data(), pubkey_ptrs.size())) {
        return false;
    }
    return true;
}

static std::optional<CPubKey> GetCPubKeyFromMuSig2KeyAggCache(secp256k1_musig_keyagg_cache& keyagg_cache)
{
    // Get the plain aggregated pubkey
    secp256k1_pubkey agg_pubkey;
    if (!secp256k1_musig_pubkey_get(secp256k1_context_static, &agg_pubkey, &keyagg_cache)) {
        return std::nullopt;
    }

    // Turn into CPubKey
    unsigned char ser_agg_pubkey[CPubKey::COMPRESSED_SIZE];
    size_t ser_agg_pubkey_len = CPubKey::COMPRESSED_SIZE;
    secp256k1_ec_pubkey_serialize(secp256k1_context_static, ser_agg_pubkey, &ser_agg_pubkey_len, &agg_pubkey, SECP256K1_EC_COMPRESSED);
    return CPubKey(ser_agg_pubkey, ser_agg_pubkey + ser_agg_pubkey_len);
}

std::optional<CPubKey> MuSig2AggregatePubkeys(const std::vector<CPubKey>& pubkeys, secp256k1_musig_keyagg_cache& keyagg_cache, const std::optional<CPubKey>& expected_aggregate)
{
    if (!GetMuSig2KeyAggCache(pubkeys, keyagg_cache)) {
        return std::nullopt;
    }
    std::optional<CPubKey> agg_key = GetCPubKeyFromMuSig2KeyAggCache(keyagg_cache);
    if (!agg_key.has_value()) return std::nullopt;
    if (expected_aggregate.has_value() && expected_aggregate != agg_key) return std::nullopt;
    return agg_key;
}

std::optional<CPubKey> MuSig2AggregatePubkeys(const std::vector<CPubKey>& pubkeys)
{
    secp256k1_musig_keyagg_cache keyagg_cache;
    return MuSig2AggregatePubkeys(pubkeys, keyagg_cache, std::nullopt);
}

CExtPubKey CreateMuSig2SyntheticXpub(const CPubKey& pubkey)
{
    CExtPubKey extpub;
    extpub.nDepth = 0;
    extpub.fingerprint.fill(0);
    extpub.nChild = 0;
    extpub.chaincode = MUSIG_CHAINCODE;
    extpub.pubkey = pubkey;
    return extpub;
}

class MuSig2SecNonceImpl
{
private:
    //! The actual secnonce itself
    secure_unique_ptr<secp256k1_musig_secnonce> m_nonce;

public:
    MuSig2SecNonceImpl() : m_nonce{make_secure_unique<secp256k1_musig_secnonce>()} {}

    // Delete copy constructors
    MuSig2SecNonceImpl(const MuSig2SecNonceImpl&) = delete;
    MuSig2SecNonceImpl& operator=(const MuSig2SecNonceImpl&) = delete;

    secp256k1_musig_secnonce* Get() const { return m_nonce.get(); }
    void Invalidate() { m_nonce.reset(); }
    bool IsValid() { return m_nonce != nullptr; }
};

MuSig2SecNonce::MuSig2SecNonce() : m_impl{std::make_unique<MuSig2SecNonceImpl>()} {}

MuSig2SecNonce::MuSig2SecNonce(MuSig2SecNonce&&) noexcept = default;
MuSig2SecNonce& MuSig2SecNonce::operator=(MuSig2SecNonce&&) noexcept = default;

MuSig2SecNonce::~MuSig2SecNonce() = default;

secp256k1_musig_secnonce* MuSig2SecNonce::Get() const
{
    return m_impl->Get();
}

void MuSig2SecNonce::Invalidate()
{
    return m_impl->Invalidate();
}

bool MuSig2SecNonce::IsValid()
{
    return m_impl->IsValid();
}

uint256 MuSig2SessionID(const CPubKey& script_pubkey, const CPubKey& part_pubkey, const uint256& sighash, const std::vector<uint8_t>& pubnonce)
{
    HashWriter hasher;
    hasher << script_pubkey << part_pubkey << sighash << pubnonce;
    return hasher.GetSHA256();
}

std::vector<uint8_t> CreateMuSig2Nonce(MuSig2SecNonce& secnonce, const uint256& sighash, const CKey& our_seckey, const CPubKey& aggregate_pubkey, const std::vector<CPubKey>& pubkeys)
{
    // Get the keyagg cache and aggregate pubkey
    secp256k1_musig_keyagg_cache keyagg_cache;
    if (!MuSig2AggregatePubkeys(pubkeys, keyagg_cache, aggregate_pubkey)) return {};

    // Parse participant pubkey
    CPubKey our_pubkey = our_seckey.GetPubKey();
    secp256k1_pubkey pubkey;
    if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &pubkey, our_pubkey.data(), our_pubkey.size())) {
        return {};
    }

    // Generate randomness for nonce
    uint256 rand;
    GetStrongRandBytes(rand);

    // Generate nonce
    secp256k1_musig_pubnonce pubnonce;
    if (!secp256k1_musig_nonce_gen(GetSecp256k1SignContext(), secnonce.Get(), &pubnonce, rand.data(), UCharCast(our_seckey.begin()), &pubkey, sighash.data(), &keyagg_cache, nullptr)) {
        return {};
    }

    // Serialize pubnonce
    std::vector<uint8_t> out;
    out.resize(MUSIG2_PUBNONCE_SIZE);
    if (!secp256k1_musig_pubnonce_serialize(secp256k1_context_static, out.data(), &pubnonce)) {
        return {};
    }

    return out;
}

std::optional<uint256> CreateMuSig2PartialSig(const uint256& sighash, const CKey& our_seckey, const CPubKey& aggregate_pubkey, const std::vector<CPubKey>& pubkeys, const std::map<CPubKey, std::vector<uint8_t>>& pubnonces, MuSig2SecNonce& secnonce, const std::vector<std::pair<uint256, bool>>& tweaks)
{
    secp256k1_keypair keypair;
    if (!secp256k1_keypair_create(GetSecp256k1SignContext(), &keypair, UCharCast(our_seckey.begin()))) return std::nullopt;

    // Get the keyagg cache and aggregate pubkey
    secp256k1_musig_keyagg_cache keyagg_cache;
    if (!MuSig2AggregatePubkeys(pubkeys, keyagg_cache, aggregate_pubkey)) return std::nullopt;

    // Check that there are enough pubnonces
    if (pubnonces.size() != pubkeys.size()) return std::nullopt;

    // Parse the pubnonces
    std::vector<std::pair<secp256k1_pubkey, secp256k1_musig_pubnonce>> signers_data;
    std::vector<const secp256k1_musig_pubnonce*> pubnonce_ptrs;
    std::optional<size_t> our_pubkey_idx;
    CPubKey our_pubkey = our_seckey.GetPubKey();
    for (const CPubKey& part_pk : 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;
        if (part_pk == our_pubkey) {
            our_pubkey_idx = signers_data.size();
        }

        auto& [secp_pk, secp_pn] = 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 (our_pubkey_idx == std::nullopt) {
        return std::nullopt;
    }
    pubnonce_ptrs.reserve(signers_data.size());
    for (auto& [_, pn] : signers_data) {
        pubnonce_ptrs.push_back(&pn);
    }

    // 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;
    }

    // Create partial signature
    secp256k1_musig_partial_sig psig;
    if (!secp256k1_musig_partial_sign(secp256k1_context_static, &psig, secnonce.Get(), &keypair, &keyagg_cache, &session)) {
        return std::nullopt;
    }
    // The secnonce must be deleted after signing to prevent nonce reuse.
    secnonce.Invalidate();

    // Verify partial signature
    if (!secp256k1_musig_partial_sig_verify(secp256k1_context_static, &psig, &(signers_data.at(*our_pubkey_idx).second), &(signers_data.at(*our_pubkey_idx).first), &keyagg_cache, &session)) {
        return std::nullopt;
    }

    // Serialize
    uint256 sig;
    if (!secp256k1_musig_partial_sig_serialize(secp256k1_context_static, sig.data(), &psig)) {
        return std::nullopt;
    }

    return sig;
}

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;
}

Coverage Report

Created: 2026-09-14 20:36

Line	Count	Source
1		// Copyright (c) 2024-present The Bitcoin Core developers
2		// Distributed under the MIT software license, see the accompanying
3		// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5		#include <musig.h>
6		#include <key.h>
7		#include <random.h>
8		#include <support/allocators/secure.h>
9
10		#include <secp256k1_musig.h>
11
12		//! MuSig2 chaincode as defined by BIP 328
13		using namespace util::hex_literals;
14		const ChainCode MUSIG_CHAINCODE{"868087ca02a6f974c4598924c36b57762d32cb45717167e300622c7167e38965"_hex_u8};
15
16		static bool GetMuSig2KeyAggCache(const std::vector<CPubKey>& pubkeys, secp256k1_musig_keyagg_cache& keyagg_cache)
17	920	{
18	920	if (pubkeys.empty()) {
19	1	return false;
20	1	}
21
22		// Parse the pubkeys
23	919	std::vector<secp256k1_pubkey> secp_pubkeys;
24	919	std::vector<const secp256k1_pubkey*> pubkey_ptrs;
25	2.58k	for (const CPubKey& pubkey : pubkeys) {
26	2.58k	if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &secp_pubkeys.emplace_back(), pubkey.data(), pubkey.size())) {
27	1	return false;
28	1	}
29	2.58k	}
30	918	pubkey_ptrs.reserve(secp_pubkeys.size());
31	2.58k	for (const secp256k1_pubkey& p : secp_pubkeys) {
32	2.58k	pubkey_ptrs.push_back(&p);
33	2.58k	}
34
35		// Aggregate the pubkey
36	918	if (!secp256k1_musig_pubkey_agg(secp256k1_context_static, nullptr, &keyagg_cache, pubkey_ptrs.data(), pubkey_ptrs.size())) {
37	0	return false;
38	0	}
39	918	return true;
40	918	}
41
42		static std::optional<CPubKey> GetCPubKeyFromMuSig2KeyAggCache(secp256k1_musig_keyagg_cache& keyagg_cache)
43	918	{
44		// Get the plain aggregated pubkey
45	918	secp256k1_pubkey agg_pubkey;
46	918	if (!secp256k1_musig_pubkey_get(secp256k1_context_static, &agg_pubkey, &keyagg_cache)) {
47	0	return std::nullopt;
48	0	}
49
50		// Turn into CPubKey
51	918	unsigned char ser_agg_pubkey[CPubKey::COMPRESSED_SIZE];
52	918	size_t ser_agg_pubkey_len = CPubKey::COMPRESSED_SIZE;
53	918	secp256k1_ec_pubkey_serialize(secp256k1_context_static, ser_agg_pubkey, &ser_agg_pubkey_len, &agg_pubkey, SECP256K1_EC_COMPRESSED);
54	918	return CPubKey(ser_agg_pubkey, ser_agg_pubkey + ser_agg_pubkey_len);
55	918	}
56
57		std::optional<CPubKey> MuSig2AggregatePubkeys(const std::vector<CPubKey>& pubkeys, secp256k1_musig_keyagg_cache& keyagg_cache, const std::optional<CPubKey>& expected_aggregate)
58	920	{
59	920	if (!GetMuSig2KeyAggCache(pubkeys, keyagg_cache)) {
60	2	return std::nullopt;
61	2	}
62	918	std::optional<CPubKey> agg_key = GetCPubKeyFromMuSig2KeyAggCache(keyagg_cache);
63	918	if (!agg_key.has_value()) return std::nullopt;
64	918	if (expected_aggregate.has_value() && expected_aggregate != agg_key) return std::nullopt;
65	918	return agg_key;
66	918	}
67
68		std::optional<CPubKey> MuSig2AggregatePubkeys(const std::vector<CPubKey>& pubkeys)
69	530	{
70	530	secp256k1_musig_keyagg_cache keyagg_cache;
71	530	return MuSig2AggregatePubkeys(pubkeys, keyagg_cache, std::nullopt);
72	530	}
73
74		CExtPubKey CreateMuSig2SyntheticXpub(const CPubKey& pubkey)
75	2.99k	{
76	2.99k	CExtPubKey extpub;
77	2.99k	extpub.nDepth = 0;
78	2.99k	extpub.fingerprint.fill(0);
79	2.99k	extpub.nChild = 0;
80	2.99k	extpub.chaincode = MUSIG_CHAINCODE;
81	2.99k	extpub.pubkey = pubkey;
82	2.99k	return extpub;
83	2.99k	}
84
85		class MuSig2SecNonceImpl
86		{
87		private:
88		//! The actual secnonce itself
89		secure_unique_ptr<secp256k1_musig_secnonce> m_nonce;
90
91		public:
92	163	MuSig2SecNonceImpl() : m_nonce{make_secure_unique<secp256k1_musig_secnonce>()} {}
93
94		// Delete copy constructors
95		MuSig2SecNonceImpl(const MuSig2SecNonceImpl&) = delete;
96		MuSig2SecNonceImpl& operator=(const MuSig2SecNonceImpl&) = delete;
97
98	315	secp256k1_musig_secnonce* Get() const { return m_nonce.get(); }
99	152	void Invalidate() { m_nonce.reset(); }
100	304	bool IsValid() { return m_nonce != nullptr; }
101		};
102
103	163	MuSig2SecNonce::MuSig2SecNonce() : m_impl{std::make_unique<MuSig2SecNonceImpl>()} {}
104
105	163	MuSig2SecNonce::MuSig2SecNonce(MuSig2SecNonce&&) noexcept = default;
106	0	MuSig2SecNonce& MuSig2SecNonce::operator=(MuSig2SecNonce&&) noexcept = default;
107
108	326	MuSig2SecNonce::~MuSig2SecNonce() = default;
109
110		secp256k1_musig_secnonce* MuSig2SecNonce::Get() const
111	315	{
112	315	return m_impl->Get();
113	315	}
114
115		void MuSig2SecNonce::Invalidate()
116	152	{
117	152	return m_impl->Invalidate();
118	152	}
119
120		bool MuSig2SecNonce::IsValid()
121	304	{
122	304	return m_impl->IsValid();
123	304	}
124
125		uint256 MuSig2SessionID(const CPubKey& script_pubkey, const CPubKey& part_pubkey, const uint256& sighash, const std::vector<uint8_t>& pubnonce)
126	435	{
127	435	HashWriter hasher;
128	435	hasher << script_pubkey << part_pubkey << sighash << pubnonce;
129	435	return hasher.GetSHA256();
130	435	}
131
132		std::vector<uint8_t> CreateMuSig2Nonce(MuSig2SecNonce& secnonce, const uint256& sighash, const CKey& our_seckey, const CPubKey& aggregate_pubkey, const std::vector<CPubKey>& pubkeys)
133	163	{
134		// Get the keyagg cache and aggregate pubkey
135	163	secp256k1_musig_keyagg_cache keyagg_cache;
136	163	if (!MuSig2AggregatePubkeys(pubkeys, keyagg_cache, aggregate_pubkey)) return {};
137
138		// Parse participant pubkey
139	163	CPubKey our_pubkey = our_seckey.GetPubKey();
140	163	secp256k1_pubkey pubkey;
141	163	if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &pubkey, our_pubkey.data(), our_pubkey.size())) {
142	0	return {};
143	0	}
144
145		// Generate randomness for nonce
146	163	uint256 rand;
147	163	GetStrongRandBytes(rand);
148
149		// Generate nonce
150	163	secp256k1_musig_pubnonce pubnonce;
151	163	if (!secp256k1_musig_nonce_gen(GetSecp256k1SignContext(), secnonce.Get(), &pubnonce, rand.data(), UCharCast(our_seckey.begin()), &pubkey, sighash.data(), &keyagg_cache, nullptr)) {
152	0	return {};
153	0	}
154
155		// Serialize pubnonce
156	163	std::vector<uint8_t> out;
157	163	out.resize(MUSIG2_PUBNONCE_SIZE);
158	163	if (!secp256k1_musig_pubnonce_serialize(secp256k1_context_static, out.data(), &pubnonce)) {
159	0	return {};
160	0	}
161
162	163	return out;
163	163	}
164
165		std::optional<uint256> CreateMuSig2PartialSig(const uint256& sighash, const CKey& our_seckey, const CPubKey& aggregate_pubkey, const std::vector<CPubKey>& pubkeys, const std::map<CPubKey, std::vector<uint8_t>>& pubnonces, MuSig2SecNonce& secnonce, const std::vector<std::pair<uint256, bool>>& tweaks)
166	152	{
167	152	secp256k1_keypair keypair;
168	152	if (!secp256k1_keypair_create(GetSecp256k1SignContext(), &keypair, UCharCast(our_seckey.begin()))) return std::nullopt;
169
170		// Get the keyagg cache and aggregate pubkey
171	152	secp256k1_musig_keyagg_cache keyagg_cache;
172	152	if (!MuSig2AggregatePubkeys(pubkeys, keyagg_cache, aggregate_pubkey)) return std::nullopt;
173
174		// Check that there are enough pubnonces
175	152	if (pubnonces.size() != pubkeys.size()) return std::nullopt;
176
177		// Parse the pubnonces
178	152	std::vector<std::pair<secp256k1_pubkey, secp256k1_musig_pubnonce>> signers_data;
179	152	std::vector<const secp256k1_musig_pubnonce*> pubnonce_ptrs;
180	152	std::optional<size_t> our_pubkey_idx;
181	152	CPubKey our_pubkey = our_seckey.GetPubKey();
182	432	for (const CPubKey& part_pk : pubkeys) {
183	432	const auto& pn_it = pubnonces.find(part_pk);
184	432	if (pn_it == pubnonces.end()) return std::nullopt;
185	432	const std::vector<uint8_t> pubnonce = pn_it->second;
186	432	if (pubnonce.size() != MUSIG2_PUBNONCE_SIZE) return std::nullopt;
187	432	if (part_pk == our_pubkey) {
188	152	our_pubkey_idx = signers_data.size();
189	152	}
190
191	432	auto& [secp_pk, secp_pn] = signers_data.emplace_back();
192
193	432	if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &secp_pk, part_pk.data(), part_pk.size())) {
194	0	return std::nullopt;
195	0	}
196
197	432	if (!secp256k1_musig_pubnonce_parse(secp256k1_context_static, &secp_pn, pubnonce.data())) {
198	0	return std::nullopt;
199	0	}
200	432	}
201	152	if (our_pubkey_idx == std::nullopt) {
202	0	return std::nullopt;
203	0	}
204	152	pubnonce_ptrs.reserve(signers_data.size());
205	432	for (auto& [_, pn] : signers_data) {
206	432	pubnonce_ptrs.push_back(&pn);
207	432	}
208
209		// Aggregate nonces
210	152	secp256k1_musig_aggnonce aggnonce;
211	152	if (!secp256k1_musig_nonce_agg(secp256k1_context_static, &aggnonce, pubnonce_ptrs.data(), pubnonce_ptrs.size())) {
212	0	return std::nullopt;
213	0	}
214
215		// Apply tweaks
216	240	for (const auto& [tweak, xonly] : tweaks) {
217	240	if (xonly) {
218	36	if (!secp256k1_musig_pubkey_xonly_tweak_add(secp256k1_context_static, nullptr, &keyagg_cache, tweak.data())) {
219	0	return std::nullopt;
220	0	}
221	204	} else if (!secp256k1_musig_pubkey_ec_tweak_add(secp256k1_context_static, nullptr, &keyagg_cache, tweak.data())) {
222	0	return std::nullopt;
223	0	}
224	240	}
225
226		// Create musig_session
227	152	secp256k1_musig_session session;
228	152	if (!secp256k1_musig_nonce_process(secp256k1_context_static, &session, &aggnonce, sighash.data(), &keyagg_cache)) {
229	0	return std::nullopt;
230	0	}
231
232		// Create partial signature
233	152	secp256k1_musig_partial_sig psig;
234	152	if (!secp256k1_musig_partial_sign(secp256k1_context_static, &psig, secnonce.Get(), &keypair, &keyagg_cache, &session)) {
235	0	return std::nullopt;
236	0	}
237		// The secnonce must be deleted after signing to prevent nonce reuse.
238	152	secnonce.Invalidate();
239
240		// Verify partial signature
241	152	if (!secp256k1_musig_partial_sig_verify(secp256k1_context_static, &psig, &(signers_data.at(our_pubkey_idx).second), &(signers_data.at(our_pubkey_idx).first), &keyagg_cache, &session)) {
242	0	return std::nullopt;
243	0	}
244
245		// Serialize
246	152	uint256 sig;
247	152	if (!secp256k1_musig_partial_sig_serialize(secp256k1_context_static, sig.data(), &psig)) {
248	0	return std::nullopt;
249	0	}
250
251	152	return sig;
252	152	}
253
254		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)
255	75	{
256	75	if (!part_pubkeys.size()) return std::nullopt;
257
258		// Get the keyagg cache and aggregate pubkey
259	75	secp256k1_musig_keyagg_cache keyagg_cache;
260	75	if (!MuSig2AggregatePubkeys(part_pubkeys, keyagg_cache, aggregate_pubkey)) return std::nullopt;
261
262		// Check if enough pubnonces and partial sigs
263	75	if (pubnonces.size() != part_pubkeys.size()) return std::nullopt;
264	75	if (partial_sigs.size() != part_pubkeys.size()) return std::nullopt;
265
266		// Parse the pubnonces and partial sigs
267	75	std::vector<std::tuple<secp256k1_pubkey, secp256k1_musig_pubnonce, secp256k1_musig_partial_sig>> signers_data;
268	75	std::vector<const secp256k1_musig_pubnonce*> pubnonce_ptrs;
269	75	std::vector<const secp256k1_musig_partial_sig*> partial_sig_ptrs;
270	213	for (const CPubKey& part_pk : part_pubkeys) {
271	213	const auto& pn_it = pubnonces.find(part_pk);
272	213	if (pn_it == pubnonces.end()) return std::nullopt;
273	213	const std::vector<uint8_t> pubnonce = pn_it->second;
274	213	if (pubnonce.size() != MUSIG2_PUBNONCE_SIZE) return std::nullopt;
275	213	const auto& it = partial_sigs.find(part_pk);
276	213	if (it == partial_sigs.end()) return std::nullopt;
277	213	const uint256& partial_sig = it->second;
278
279	213	auto& [secp_pk, secp_pn, secp_ps] = signers_data.emplace_back();
280
281	213	if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &secp_pk, part_pk.data(), part_pk.size())) {
282	0	return std::nullopt;
283	0	}
284
285	213	if (!secp256k1_musig_pubnonce_parse(secp256k1_context_static, &secp_pn, pubnonce.data())) {
286	0	return std::nullopt;
287	0	}
288
289	213	if (!secp256k1_musig_partial_sig_parse(secp256k1_context_static, &secp_ps, partial_sig.data())) {
290	0	return std::nullopt;
291	0	}
292	213	}
293	75	pubnonce_ptrs.reserve(signers_data.size());
294	75	partial_sig_ptrs.reserve(signers_data.size());
295	213	for (auto& [_, pn, ps] : signers_data) {
296	213	pubnonce_ptrs.push_back(&pn);
297	213	partial_sig_ptrs.push_back(&ps);
298	213	}
299
300		// Aggregate nonces
301	75	secp256k1_musig_aggnonce aggnonce;
302	75	if (!secp256k1_musig_nonce_agg(secp256k1_context_static, &aggnonce, pubnonce_ptrs.data(), pubnonce_ptrs.size())) {
303	0	return std::nullopt;
304	0	}
305
306		// Apply tweaks
307	120	for (const auto& [tweak, xonly] : tweaks) {
308	120	if (xonly) {
309	18	if (!secp256k1_musig_pubkey_xonly_tweak_add(secp256k1_context_static, nullptr, &keyagg_cache, tweak.data())) {
310	0	return std::nullopt;
311	0	}
312	102	} else if (!secp256k1_musig_pubkey_ec_tweak_add(secp256k1_context_static, nullptr, &keyagg_cache, tweak.data())) {
313	0	return std::nullopt;
314	0	}
315	120	}
316
317		// Create musig_session
318	75	secp256k1_musig_session session;
319	75	if (!secp256k1_musig_nonce_process(secp256k1_context_static, &session, &aggnonce, sighash.data(), &keyagg_cache)) {
320	0	return std::nullopt;
321	0	}
322
323		// Verify partial sigs
324	213	for (const auto& [pk, pb, ps] : signers_data) {
325	213	if (!secp256k1_musig_partial_sig_verify(secp256k1_context_static, &ps, &pb, &pk, &keyagg_cache, &session)) {
326	0	return std::nullopt;
327	0	}
328	213	}
329
330		// Aggregate partial sigs
331	75	std::vector<uint8_t> sig;
332	75	sig.resize(64);
333	75	if (!secp256k1_musig_partial_sig_agg(secp256k1_context_static, sig.data(), &session, partial_sig_ptrs.data(), partial_sig_ptrs.size())) {
334	0	return std::nullopt;
335	0	}
336
337	75	return sig;
338	75	}