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secp256k1 provides us secp256k1_musig_keyagg_cache objects which we are used as part of session info and to get the aggregate pubkey. These helper functions help us convert to/from the secp256k1 C objects into the Bitcoin Core C++ objects.
54 lines
1.9 KiB
C++
54 lines
1.9 KiB
C++
// Copyright (c) 2024-present The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <musig.h>
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#include <secp256k1_musig.h>
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bool GetMuSig2KeyAggCache(const std::vector<CPubKey>& pubkeys, secp256k1_musig_keyagg_cache& keyagg_cache)
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{
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// Parse the pubkeys
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std::vector<secp256k1_pubkey> secp_pubkeys;
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std::vector<const secp256k1_pubkey*> pubkey_ptrs;
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for (const CPubKey& pubkey : pubkeys) {
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if (!secp256k1_ec_pubkey_parse(secp256k1_context_static, &secp_pubkeys.emplace_back(), pubkey.data(), pubkey.size())) {
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return false;
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}
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}
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pubkey_ptrs.reserve(secp_pubkeys.size());
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for (const secp256k1_pubkey& p : secp_pubkeys) {
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pubkey_ptrs.push_back(&p);
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}
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// Aggregate the pubkey
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if (!secp256k1_musig_pubkey_agg(secp256k1_context_static, nullptr, &keyagg_cache, pubkey_ptrs.data(), pubkey_ptrs.size())) {
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return false;
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}
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return true;
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}
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std::optional<CPubKey> GetCPubKeyFromMuSig2KeyAggCache(secp256k1_musig_keyagg_cache& keyagg_cache)
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{
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// Get the plain aggregated pubkey
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secp256k1_pubkey agg_pubkey;
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if (!secp256k1_musig_pubkey_get(secp256k1_context_static, &agg_pubkey, &keyagg_cache)) {
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return std::nullopt;
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}
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// Turn into CPubKey
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unsigned char ser_agg_pubkey[CPubKey::COMPRESSED_SIZE];
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size_t ser_agg_pubkey_len = CPubKey::COMPRESSED_SIZE;
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secp256k1_ec_pubkey_serialize(secp256k1_context_static, ser_agg_pubkey, &ser_agg_pubkey_len, &agg_pubkey, SECP256K1_EC_COMPRESSED);
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return CPubKey(ser_agg_pubkey, ser_agg_pubkey + ser_agg_pubkey_len);
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}
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std::optional<CPubKey> MuSig2AggregatePubkeys(const std::vector<CPubKey>& pubkeys)
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{
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secp256k1_musig_keyagg_cache keyagg_cache;
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if (!GetMuSig2KeyAggCache(pubkeys, keyagg_cache)) {
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return std::nullopt;
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}
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return GetCPubKeyFromMuSig2KeyAggCache(keyagg_cache);
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}
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