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Diffstat (limited to 'src/multisig/multisig_kex_msg.cpp')
| -rw-r--r-- | src/multisig/multisig_kex_msg.cpp | 290 |
1 files changed, 290 insertions, 0 deletions
diff --git a/src/multisig/multisig_kex_msg.cpp b/src/multisig/multisig_kex_msg.cpp new file mode 100644 index 000000000..2bbceb19d --- /dev/null +++ b/src/multisig/multisig_kex_msg.cpp @@ -0,0 +1,290 @@ +// Copyright (c) 2021, The Monero Project +// +// All rights reserved. +// +// Redistribution and use in source and binary forms, with or without modification, are +// permitted provided that the following conditions are met: +// +// 1. Redistributions of source code must retain the above copyright notice, this list of +// conditions and the following disclaimer. +// +// 2. Redistributions in binary form must reproduce the above copyright notice, this list +// of conditions and the following disclaimer in the documentation and/or other +// materials provided with the distribution. +// +// 3. Neither the name of the copyright holder nor the names of its contributors may be +// used to endorse or promote products derived from this software without specific +// prior written permission. +// +// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY +// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF +// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL +// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, +// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, +// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS +// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, +// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF +// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + +#include "multisig_kex_msg.h" +#include "multisig_kex_msg_serialization.h" + +#include "common/base58.h" +#include "crypto/crypto.h" +extern "C" +{ +#include "crypto/crypto-ops.h" +} +#include "cryptonote_basic/cryptonote_format_utils.h" +#include "include_base_utils.h" +#include "ringct/rctOps.h" +#include "serialization/binary_archive.h" +#include "serialization/serialization.h" + +#include <boost/utility/string_ref.hpp> + +#include <sstream> +#include <utility> +#include <vector> + + +#undef MONERO_DEFAULT_LOG_CATEGORY +#define MONERO_DEFAULT_LOG_CATEGORY "multisig" + +const boost::string_ref MULTISIG_KEX_V1_MAGIC{"MultisigV1"}; +const boost::string_ref MULTISIG_KEX_MSG_V1_MAGIC{"MultisigxV1"}; +const boost::string_ref MULTISIG_KEX_MSG_V2_MAGIC_1{"MultisigxV2R1"}; //round 1 +const boost::string_ref MULTISIG_KEX_MSG_V2_MAGIC_N{"MultisigxV2Rn"}; //round n > 1 + +namespace multisig +{ + //---------------------------------------------------------------------------------------------------------------------- + // multisig_kex_msg: EXTERNAL + //---------------------------------------------------------------------------------------------------------------------- + multisig_kex_msg::multisig_kex_msg(const std::uint32_t round, + const crypto::secret_key &signing_privkey, + std::vector<crypto::public_key> msg_pubkeys, + const crypto::secret_key &msg_privkey) : + m_kex_round{round} + { + CHECK_AND_ASSERT_THROW_MES(round > 0, "Kex round must be > 0."); + CHECK_AND_ASSERT_THROW_MES(sc_check((const unsigned char*)&signing_privkey) == 0 && + signing_privkey != crypto::null_skey, "Invalid msg signing key."); + + if (round == 1) + { + CHECK_AND_ASSERT_THROW_MES(sc_check((const unsigned char*)&msg_privkey) == 0 && + msg_privkey != crypto::null_skey, "Invalid msg privkey."); + + m_msg_privkey = msg_privkey; + } + else + { + for (const auto &pubkey : msg_pubkeys) + { + CHECK_AND_ASSERT_THROW_MES(pubkey != crypto::null_pkey && pubkey != rct::rct2pk(rct::identity()), + "Pubkey for message was invalid."); + CHECK_AND_ASSERT_THROW_MES((rct::scalarmultKey(rct::pk2rct(pubkey), rct::curveOrder()) == rct::identity()), + "Pubkey for message was not in prime subgroup."); + } + + m_msg_pubkeys = std::move(msg_pubkeys); + } + CHECK_AND_ASSERT_THROW_MES(crypto::secret_key_to_public_key(signing_privkey, m_signing_pubkey), + "Failed to derive public key"); + + // sets message and signing pub key + construct_msg(signing_privkey); + } + //---------------------------------------------------------------------------------------------------------------------- + // multisig_kex_msg: EXTERNAL + //---------------------------------------------------------------------------------------------------------------------- + multisig_kex_msg::multisig_kex_msg(std::string msg) : m_msg{std::move(msg)} + { + parse_and_validate_msg(); + } + //---------------------------------------------------------------------------------------------------------------------- + // multisig_kex_msg: INTERNAL + //---------------------------------------------------------------------------------------------------------------------- + crypto::hash multisig_kex_msg::get_msg_to_sign() const + { + //// + // msg_content = kex_round | signing_pubkey | expand(msg_pubkeys) | OPTIONAL msg_privkey + // sign_msg = versioning-domain-sep | msg_content + /// + + std::string data; + CHECK_AND_ASSERT_THROW_MES(MULTISIG_KEX_MSG_V2_MAGIC_1.size() == MULTISIG_KEX_MSG_V2_MAGIC_N.size(), + "Multisig kex msg magic inconsistency."); + data.reserve(MULTISIG_KEX_MSG_V2_MAGIC_1.size() + 4 + 32*(1 + (m_kex_round == 1 ? 1 : 0) + m_msg_pubkeys.size())); + + // versioning domain-sep + if (m_kex_round == 1) + data.append(MULTISIG_KEX_MSG_V2_MAGIC_1.data(), MULTISIG_KEX_MSG_V2_MAGIC_1.size()); + else + data.append(MULTISIG_KEX_MSG_V2_MAGIC_N.data(), MULTISIG_KEX_MSG_V2_MAGIC_N.size()); + + // kex_round as little-endian bytes + for (std::size_t i{0}; i < 4; ++i) + { + data += static_cast<char>(m_kex_round >> i*8); + } + + // signing pubkey + data.append((const char *)&m_signing_pubkey, sizeof(crypto::public_key)); + + // add msg privkey if kex_round == 1 + if (m_kex_round == 1) + data.append((const char *)&m_msg_privkey, sizeof(crypto::secret_key)); + else + { + // only add pubkeys if not round 1 + + // msg pubkeys + for (const auto &key : m_msg_pubkeys) + data.append((const char *)&key, sizeof(crypto::public_key)); + } + + // message to sign + crypto::hash hash; + crypto::cn_fast_hash(data.data(), data.size(), hash); + + return hash; + } + //---------------------------------------------------------------------------------------------------------------------- + // multisig_kex_msg: INTERNAL + //---------------------------------------------------------------------------------------------------------------------- + void multisig_kex_msg::construct_msg(const crypto::secret_key &signing_privkey) + { + //// + // msg_content = kex_round | signing_pubkey | expand(msg_pubkeys) | OPTIONAL msg_privkey + // sign_msg = versioning-domain-sep | msg_content + // msg = versioning-domain-sep | serialize(msg_content | crypto_sig[signing_privkey](sign_msg)) + /// + + // sign the message + crypto::signature msg_signature; + crypto::hash msg_to_sign{get_msg_to_sign()}; + crypto::generate_signature(msg_to_sign, m_signing_pubkey, signing_privkey, msg_signature); + + // assemble the message + m_msg.clear(); + + std::stringstream serialized_msg_ss; + binary_archive<true> b_archive(serialized_msg_ss); + + if (m_kex_round == 1) + { + m_msg.append(MULTISIG_KEX_MSG_V2_MAGIC_1.data(), MULTISIG_KEX_MSG_V2_MAGIC_1.size()); + + multisig_kex_msg_serializable_round1 msg_serializable; + msg_serializable.msg_privkey = m_msg_privkey; + msg_serializable.signing_pubkey = m_signing_pubkey; + msg_serializable.signature = msg_signature; + + CHECK_AND_ASSERT_THROW_MES(::serialization::serialize(b_archive, msg_serializable), + "Failed to serialize multisig kex msg"); + } + else + { + m_msg.append(MULTISIG_KEX_MSG_V2_MAGIC_N.data(), MULTISIG_KEX_MSG_V2_MAGIC_N.size()); + + multisig_kex_msg_serializable_general msg_serializable; + msg_serializable.kex_round = m_kex_round; + msg_serializable.msg_pubkeys = m_msg_pubkeys; + msg_serializable.signing_pubkey = m_signing_pubkey; + msg_serializable.signature = msg_signature; + + CHECK_AND_ASSERT_THROW_MES(::serialization::serialize(b_archive, msg_serializable), + "Failed to serialize multisig kex msg"); + } + + m_msg.append(tools::base58::encode(serialized_msg_ss.str())); + } + //---------------------------------------------------------------------------------------------------------------------- + // multisig_kex_msg: INTERNAL + //---------------------------------------------------------------------------------------------------------------------- + void multisig_kex_msg::parse_and_validate_msg() + { + // check message type + CHECK_AND_ASSERT_THROW_MES(m_msg.size() > 0, "Kex message unexpectedly empty."); + CHECK_AND_ASSERT_THROW_MES(m_msg.substr(0, MULTISIG_KEX_V1_MAGIC.size()) != MULTISIG_KEX_V1_MAGIC, + "V1 multisig kex messages are deprecated (unsafe)."); + CHECK_AND_ASSERT_THROW_MES(m_msg.substr(0, MULTISIG_KEX_MSG_V1_MAGIC.size()) != MULTISIG_KEX_MSG_V1_MAGIC, + "V1 multisig kex messages are deprecated (unsafe)."); + + // deserialize the message + std::string msg_no_magic; + CHECK_AND_ASSERT_THROW_MES(MULTISIG_KEX_MSG_V2_MAGIC_1.size() == MULTISIG_KEX_MSG_V2_MAGIC_N.size(), + "Multisig kex msg magic inconsistency."); + CHECK_AND_ASSERT_THROW_MES(tools::base58::decode(m_msg.substr(MULTISIG_KEX_MSG_V2_MAGIC_1.size()), msg_no_magic), + "Multisig kex msg decoding error."); + binary_archive<false> b_archive{epee::strspan<std::uint8_t>(msg_no_magic)}; + crypto::signature msg_signature; + + if (m_msg.substr(0, MULTISIG_KEX_MSG_V2_MAGIC_1.size()) == MULTISIG_KEX_MSG_V2_MAGIC_1) + { + // try round 1 message + multisig_kex_msg_serializable_round1 kex_msg_rnd1; + + if (::serialization::serialize(b_archive, kex_msg_rnd1)) + { + // in round 1 the message stores a private ancillary key component for the multisig account + // that will be shared by all participants (e.g. a shared private view key) + m_kex_round = 1; + m_msg_privkey = kex_msg_rnd1.msg_privkey; + m_signing_pubkey = kex_msg_rnd1.signing_pubkey; + msg_signature = kex_msg_rnd1.signature; + } + else + { + CHECK_AND_ASSERT_THROW_MES(false, "Deserializing kex msg failed."); + } + } + else if (m_msg.substr(0, MULTISIG_KEX_MSG_V2_MAGIC_N.size()) == MULTISIG_KEX_MSG_V2_MAGIC_N) + { + // try general message + multisig_kex_msg_serializable_general kex_msg_general; + + if (::serialization::serialize(b_archive, kex_msg_general)) + { + m_kex_round = kex_msg_general.kex_round; + m_msg_privkey = crypto::null_skey; + m_msg_pubkeys = std::move(kex_msg_general.msg_pubkeys); + m_signing_pubkey = kex_msg_general.signing_pubkey; + msg_signature = kex_msg_general.signature; + + CHECK_AND_ASSERT_THROW_MES(m_kex_round > 1, "Invalid kex message round (must be > 1 for the general msg type)."); + } + else + { + CHECK_AND_ASSERT_THROW_MES(false, "Deserializing kex msg failed."); + } + } + else + { + // unknown message type + CHECK_AND_ASSERT_THROW_MES(false, "Only v2 multisig kex messages are supported."); + } + + // checks + for (const auto &pubkey: m_msg_pubkeys) + { + CHECK_AND_ASSERT_THROW_MES(pubkey != crypto::null_pkey && pubkey != rct::rct2pk(rct::identity()), + "Pubkey from message was invalid."); + CHECK_AND_ASSERT_THROW_MES(rct::isInMainSubgroup(rct::pk2rct(pubkey)), + "Pubkey from message was not in prime subgroup."); + } + + CHECK_AND_ASSERT_THROW_MES(m_signing_pubkey != crypto::null_pkey && m_signing_pubkey != rct::rct2pk(rct::identity()), + "Message signing key was invalid."); + CHECK_AND_ASSERT_THROW_MES(rct::isInMainSubgroup(rct::pk2rct(m_signing_pubkey)), + "Message signing key was not in prime subgroup."); + + // validate signature + crypto::hash signed_msg{get_msg_to_sign()}; + CHECK_AND_ASSERT_THROW_MES(crypto::check_signature(signed_msg, m_signing_pubkey, msg_signature), + "Multisig kex msg signature invalid."); + } + //---------------------------------------------------------------------------------------------------------------------- +} //namespace multisig |