// Copyright (c) 2017-2019, 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
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// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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#include <unordered_set>
#include "include_base_utils.h"
#include "crypto/crypto.h"
#include "ringct/rctOps.h"
#include "cryptonote_basic/account.h"
#include "cryptonote_basic/cryptonote_format_utils.h"
#include "multisig.h"
#include "cryptonote_config.h"
#undef MONERO_DEFAULT_LOG_CATEGORY
#define MONERO_DEFAULT_LOG_CATEGORY "multisig"
using namespace std;
namespace cryptonote
{
//-----------------------------------------------------------------
crypto::secret_key get_multisig_blinded_secret_key(const crypto::secret_key &key)
{
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));
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;
}
//-----------------------------------------------------------------
void generate_multisig_N_N(const account_keys &keys, const std::vector<crypto::public_key> &spend_keys, std::vector<crypto::secret_key> &multisig_keys, rct::key &spend_skey, rct::key &spend_pkey)
{
// the multisig spend public key is the sum of all spend public keys
multisig_keys.clear();
const crypto::secret_key spend_secret_key = get_multisig_blinded_secret_key(keys.m_spend_secret_key);
CHECK_AND_ASSERT_THROW_MES(crypto::secret_key_to_public_key(spend_secret_key, (crypto::public_key&)spend_pkey), "Failed to derive public key");
for (const auto &k: spend_keys)
rct::addKeys(spend_pkey, spend_pkey, rct::pk2rct(k));
multisig_keys.push_back(spend_secret_key);
spend_skey = rct::sk2rct(spend_secret_key);
}
//-----------------------------------------------------------------
void generate_multisig_N1_N(const account_keys &keys, const std::vector<crypto::public_key> &spend_keys, std::vector<crypto::secret_key> &multisig_keys, rct::key &spend_skey, rct::key &spend_pkey)
{
multisig_keys.clear();
spend_pkey = rct::identity();
spend_skey = rct::zero();
// create all our composite private keys
crypto::secret_key blinded_skey = get_multisig_blinded_secret_key(keys.m_spend_secret_key);
for (const auto &k: spend_keys)
{
rct::key sk = rct::scalarmultKey(rct::pk2rct(k), rct::sk2rct(blinded_skey));
crypto::secret_key msk = get_multisig_blinded_secret_key(rct::rct2sk(sk));
memwipe(&sk, sizeof(sk));
multisig_keys.push_back(msk);
sc_add(spend_skey.bytes, spend_skey.bytes, (const unsigned char*)msk.data);
}
}
//-----------------------------------------------------------------
std::vector<crypto::public_key> generate_multisig_derivations(const account_keys &keys, const std::vector<crypto::public_key> &derivations)
{
std::vector<crypto::public_key> multisig_keys;
crypto::secret_key blinded_skey = get_multisig_blinded_secret_key(keys.m_spend_secret_key);
for (const auto &k: derivations)
{
rct::key d = rct::scalarmultKey(rct::pk2rct(k), rct::sk2rct(blinded_skey));
multisig_keys.push_back(rct::rct2pk(d));
}
return multisig_keys;
}
//-----------------------------------------------------------------
crypto::secret_key calculate_multisig_signer_key(const std::vector<crypto::secret_key>& multisig_keys)
{
rct::key secret_key = rct::zero();
for (const auto &k: multisig_keys)
{
sc_add(secret_key.bytes, secret_key.bytes, (const unsigned char*)k.data);
}
return rct::rct2sk(secret_key);
}
//-----------------------------------------------------------------
std::vector<crypto::secret_key> calculate_multisig_keys(const std::vector<crypto::public_key>& derivations)
{
std::vector<crypto::secret_key> multisig_keys;
multisig_keys.reserve(derivations.size());
for (const auto &k: derivations)
{
multisig_keys.emplace_back(get_multisig_blinded_secret_key(rct::rct2sk(rct::pk2rct(k))));
}
return multisig_keys;
}
//-----------------------------------------------------------------
crypto::secret_key generate_multisig_view_secret_key(const crypto::secret_key &skey, const std::vector<crypto::secret_key> &skeys)
{
crypto::secret_key view_skey = get_multisig_blinded_secret_key(skey);
for (const auto &k: skeys)
sc_add((unsigned char*)&view_skey, rct::sk2rct(view_skey).bytes, rct::sk2rct(k).bytes);
return view_skey;
}
//-----------------------------------------------------------------
crypto::public_key generate_multisig_M_N_spend_public_key(const std::vector<crypto::public_key> &pkeys)
{
rct::key spend_public_key = rct::identity();
for (const auto &pk: pkeys)
{
rct::addKeys(spend_public_key, spend_public_key, rct::pk2rct(pk));
}
return rct::rct2pk(spend_public_key);
}
//-----------------------------------------------------------------
bool generate_multisig_key_image(const account_keys &keys, 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 account_keys &keys, const std::unordered_map<crypto::public_key, 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, size_t real_output_index, const std::vector<crypto::key_image> &pkis, crypto::key_image &ki)
{
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;
for (size_t m = 0; m < keys.m_multisig_keys.size(); ++m)
{
crypto::key_image pki;
bool r = cryptonote::generate_multisig_key_image(keys, m, out_key, pki);
if (!r)
return false;
used.insert(pki);
}
for (const auto &pki: pkis)
{
if (used.find(pki) == used.end())
{
used.insert(pki);
rct::addKeys((rct::key&)ki, rct::ki2rct(ki), rct::ki2rct(pki));
}
}
return true;
}
//-----------------------------------------------------------------
uint32_t multisig_rounds_required(uint32_t participants, uint32_t threshold)
{
CHECK_AND_ASSERT_THROW_MES(participants >= threshold, "participants must be greater or equal than threshold");
return participants - threshold + 1;
}
}
