// Copyright (c) 2017-2023, The Monero Project
//
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// 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.
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// 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.
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// 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
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//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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#include "crypto/crypto.h"
#include "cryptonote_basic/account.h"
#include "cryptonote_basic/cryptonote_format_utils.h"
#include "cryptonote_config.h"
#include "include_base_utils.h"
#include "multisig.h"
#include "ringct/rctOps.h"
#include <algorithm>
#include <unordered_map>
#include <unordered_set>
#include <vector>
#undef MONERO_DEFAULT_LOG_CATEGORY
#define MONERO_DEFAULT_LOG_CATEGORY "multisig"
namespace multisig
{
//----------------------------------------------------------------------------------------------------------------------
crypto::secret_key get_multisig_blinded_secret_key(const crypto::secret_key &key)
{
CHECK_AND_ASSERT_THROW_MES(key != crypto::null_skey, "Unexpected null secret key (danger!).");
rct::key multisig_salt;
static_assert(sizeof(rct::key) == sizeof(config::HASH_KEY_MULTISIG), "Hash domain separator is an unexpected size");
memcpy(multisig_salt.bytes, config::HASH_KEY_MULTISIG, sizeof(rct::key));
// private key = H(key, domain-sep)
rct::keyV data;
data.reserve(2);
data.push_back(rct::sk2rct(key));
data.push_back(multisig_salt);
crypto::secret_key result = rct::rct2sk(rct::hash_to_scalar(data));
memwipe(&data[0], sizeof(rct::key));
return result;
}
//----------------------------------------------------------------------------------------------------------------------
bool generate_multisig_key_image(const cryptonote::account_keys &keys,
std::size_t multisig_key_index,
const crypto::public_key& out_key,
crypto::key_image& ki)
{
if (multisig_key_index >= keys.m_multisig_keys.size())
return false;
crypto::generate_key_image(out_key, keys.m_multisig_keys[multisig_key_index], ki);
return true;
}
//----------------------------------------------------------------------------------------------------------------------
void generate_multisig_LR(const crypto::public_key pkey,
const crypto::secret_key &k,
crypto::public_key &L,
crypto::public_key &R)
{
rct::scalarmultBase((rct::key&)L, rct::sk2rct(k));
crypto::generate_key_image(pkey, k, (crypto::key_image&)R);
}
//----------------------------------------------------------------------------------------------------------------------
bool generate_multisig_composite_key_image(const cryptonote::account_keys &keys,
const std::unordered_map<crypto::public_key, cryptonote::subaddress_index> &subaddresses,
const crypto::public_key &out_key,
const crypto::public_key &tx_public_key,
const std::vector<crypto::public_key> &additional_tx_public_keys,
std::size_t real_output_index,
const std::vector<crypto::key_image> &pkis,
crypto::key_image &ki)
{
// create a multisig partial key image
// KI_partial = ([view key component] + [subaddress component] + [multisig privkeys]) * Hp(output one-time address)
// - the 'multisig priv keys' here are those held by the local account
// - later, we add in the components held by other participants
cryptonote::keypair in_ephemeral;
if (!cryptonote::generate_key_image_helper(keys, subaddresses, out_key, tx_public_key, additional_tx_public_keys, real_output_index, in_ephemeral, ki, keys.get_device()))
return false;
std::unordered_set<crypto::key_image> used;
// create a key image component for each of the local account's multisig private keys
for (std::size_t m = 0; m < keys.m_multisig_keys.size(); ++m)
{
crypto::key_image pki;
// pki = keys.m_multisig_keys[m] * Hp(out_key)
// pki = key image component
// out_key = one-time address of an output owned by the multisig group
bool r = generate_multisig_key_image(keys, m, out_key, pki);
if (!r)
return false;
// this KI component is 'used' because it was included in the partial key image 'ki' above
used.insert(pki);
}
// add the KI components from other participants to the partial KI
// if they not included yet
for (const auto &pki: pkis)
{
if (used.find(pki) == used.end())
{
// ignore components that have already been 'used'
used.insert(pki);
// KI_partial = KI_partial + KI_component[...]
rct::addKeys((rct::key&)ki, rct::ki2rct(ki), rct::ki2rct(pki));
}
}
// at the end, 'ki' will hold the true key image for our output if inputs were sufficient
// - if 'pkis' (the other participants' KI components) is missing some components
// then 'ki' will not be complete
return true;
}
//----------------------------------------------------------------------------------------------------------------------
} //namespace multisig
