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monero/src/crypto/crypto.cpp

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// Copyright (c) 2014-2017, 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.
//
// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
#include <cassert>
#include <cstddef>
#include <cstdint>
#include <cstdlib>
#include <cstring>
#include <memory>
#include <boost/thread/mutex.hpp>
#include <boost/thread/lock_guard.hpp>
#include "common/varint.h"
#include "warnings.h"
#include "crypto.h"
#include "hash.h"
#if !defined(__FreeBSD__) && !defined(__OpenBSD__) && !defined(__DragonFly__)
#include <alloca.h>
#else
#include <stdlib.h>
#endif
namespace crypto {
using std::abort;
using std::int32_t;
using std::int64_t;
using std::size_t;
using std::uint32_t;
using std::uint64_t;
extern "C" {
#include "crypto-ops.h"
#include "random.h"
}
boost::mutex random_lock;
static inline unsigned char *operator &(ec_point &point) {
return &reinterpret_cast<unsigned char &>(point);
}
static inline const unsigned char *operator &(const ec_point &point) {
return &reinterpret_cast<const unsigned char &>(point);
}
static inline unsigned char *operator &(ec_scalar &scalar) {
return &reinterpret_cast<unsigned char &>(scalar);
}
static inline const unsigned char *operator &(const ec_scalar &scalar) {
return &reinterpret_cast<const unsigned char &>(scalar);
}
/* generate a random 32-byte (256-bit) integer and copy it to res */
static inline void random_scalar(ec_scalar &res) {
unsigned char tmp[64];
generate_random_bytes_not_thread_safe(64, tmp);
sc_reduce(tmp);
memcpy(&res, tmp, 32);
}
static inline void hash_to_scalar(const void *data, size_t length, ec_scalar &res) {
cn_fast_hash(data, length, reinterpret_cast<hash &>(res));
sc_reduce32(&res);
}
/*
* generate public and secret keys from a random 256-bit integer
* TODO: allow specifiying random value (for wallet recovery)
*
*/
secret_key crypto_ops::generate_keys(public_key &pub, secret_key &sec, const secret_key& recovery_key, bool recover) {
boost::lock_guard<boost::mutex> lock(random_lock);
ge_p3 point;
secret_key rng;
if (recover)
{
rng = recovery_key;
}
else
{
random_scalar(rng);
}
sec = rng;
sc_reduce32(&sec); // reduce in case second round of keys (sendkeys)
ge_scalarmult_base(&point, &sec);
ge_p3_tobytes(&pub, &point);
return rng;
}
bool crypto_ops::check_key(const public_key &key) {
ge_p3 point;
return ge_frombytes_vartime(&point, &key) == 0;
}
bool crypto_ops::secret_key_to_public_key(const secret_key &sec, public_key &pub) {
ge_p3 point;
if (sc_check(&sec) != 0) {
return false;
}
ge_scalarmult_base(&point, &sec);
ge_p3_tobytes(&pub, &point);
return true;
}
bool crypto_ops::generate_key_derivation(const public_key &key1, const secret_key &key2, key_derivation &derivation) {
ge_p3 point;
ge_p2 point2;
ge_p1p1 point3;
assert(sc_check(&key2) == 0);
if (ge_frombytes_vartime(&point, &key1) != 0) {
return false;
}
ge_scalarmult(&point2, &key2, &point);
ge_mul8(&point3, &point2);
ge_p1p1_to_p2(&point2, &point3);
ge_tobytes(&derivation, &point2);
return true;
}
void crypto_ops::derivation_to_scalar(const key_derivation &derivation, size_t output_index, ec_scalar &res) {
struct {
key_derivation derivation;
char output_index[(sizeof(size_t) * 8 + 6) / 7];
} buf;
char *end = buf.output_index;
buf.derivation = derivation;
tools::write_varint(end, output_index);
assert(end <= buf.output_index + sizeof buf.output_index);
hash_to_scalar(&buf, end - reinterpret_cast<char *>(&buf), res);
}
bool crypto_ops::derive_public_key(const key_derivation &derivation, size_t output_index,
const public_key &base, public_key &derived_key) {
ec_scalar scalar;
ge_p3 point1;
ge_p3 point2;
ge_cached point3;
ge_p1p1 point4;
ge_p2 point5;
if (ge_frombytes_vartime(&point1, &base) != 0) {
return false;
}
derivation_to_scalar(derivation, output_index, scalar);
ge_scalarmult_base(&point2, &scalar);
ge_p3_to_cached(&point3, &point2);
ge_add(&point4, &point1, &point3);
ge_p1p1_to_p2(&point5, &point4);
ge_tobytes(&derived_key, &point5);
return true;
}
void crypto_ops::derive_secret_key(const key_derivation &derivation, size_t output_index,
const secret_key &base, secret_key &derived_key) {
ec_scalar scalar;
assert(sc_check(&base) == 0);
derivation_to_scalar(derivation, output_index, scalar);
sc_add(&derived_key, &base, &scalar);
}
struct s_comm {
hash h;
ec_point key;
ec_point comm;
};
void crypto_ops::generate_signature(const hash &prefix_hash, const public_key &pub, const secret_key &sec, signature &sig) {
boost::lock_guard<boost::mutex> lock(random_lock);
ge_p3 tmp3;
ec_scalar k;
s_comm buf;
#if !defined(NDEBUG)
{
ge_p3 t;
public_key t2;
assert(sc_check(&sec) == 0);
ge_scalarmult_base(&t, &sec);
ge_p3_tobytes(&t2, &t);
assert(pub == t2);
}
#endif
buf.h = prefix_hash;
buf.key = pub;
random_scalar(k);
ge_scalarmult_base(&tmp3, &k);
ge_p3_tobytes(&buf.comm, &tmp3);
hash_to_scalar(&buf, sizeof(s_comm), sig.c);
sc_mulsub(&sig.r, &sig.c, &sec, &k);
}
bool crypto_ops::check_signature(const hash &prefix_hash, const public_key &pub, const signature &sig) {
ge_p2 tmp2;
ge_p3 tmp3;
ec_scalar c;
s_comm buf;
assert(check_key(pub));
buf.h = prefix_hash;
buf.key = pub;
if (ge_frombytes_vartime(&tmp3, &pub) != 0) {
return false;
}
if (sc_check(&sig.c) != 0 || sc_check(&sig.r) != 0) {
return false;
}
ge_double_scalarmult_base_vartime(&tmp2, &sig.c, &tmp3, &sig.r);
ge_tobytes(&buf.comm, &tmp2);
hash_to_scalar(&buf, sizeof(s_comm), c);
sc_sub(&c, &c, &sig.c);
return sc_isnonzero(&c) == 0;
}
static void hash_to_ec(const public_key &key, ge_p3 &res) {
hash h;
ge_p2 point;
ge_p1p1 point2;
cn_fast_hash(std::addressof(key), sizeof(public_key), h);
ge_fromfe_frombytes_vartime(&point, reinterpret_cast<const unsigned char *>(&h));
ge_mul8(&point2, &point);
ge_p1p1_to_p3(&res, &point2);
}
void crypto_ops::generate_key_image(const public_key &pub, const secret_key &sec, key_image &image) {
ge_p3 point;
ge_p2 point2;
assert(sc_check(&sec) == 0);
hash_to_ec(pub, point);
ge_scalarmult(&point2, &sec, &point);
ge_tobytes(&image, &point2);
}
PUSH_WARNINGS
DISABLE_VS_WARNINGS(4200)
struct ec_point_pair {
ec_point a, b;
};
struct rs_comm {
hash h;
struct ec_point_pair ab[];
};
POP_WARNINGS
static inline size_t rs_comm_size(size_t pubs_count) {
return sizeof(rs_comm) + pubs_count * sizeof(ec_point_pair);
}
void crypto_ops::generate_ring_signature(const hash &prefix_hash, const key_image &image,
const public_key *const *pubs, size_t pubs_count,
const secret_key &sec, size_t sec_index,
signature *sig) {
boost::lock_guard<boost::mutex> lock(random_lock);
size_t i;
ge_p3 image_unp;
ge_dsmp image_pre;
ec_scalar sum, k, h;
rs_comm *const buf = reinterpret_cast<rs_comm *>(alloca(rs_comm_size(pubs_count)));
assert(sec_index < pubs_count);
#if !defined(NDEBUG)
{
ge_p3 t;
public_key t2;
key_image t3;
assert(sc_check(&sec) == 0);
ge_scalarmult_base(&t, &sec);
ge_p3_tobytes(&t2, &t);
assert(*pubs[sec_index] == t2);
generate_key_image(*pubs[sec_index], sec, t3);
assert(image == t3);
for (i = 0; i < pubs_count; i++) {
assert(check_key(*pubs[i]));
}
}
#endif
if (ge_frombytes_vartime(&image_unp, &image) != 0) {
abort();
}
ge_dsm_precomp(image_pre, &image_unp);
sc_0(&sum);
buf->h = prefix_hash;
for (i = 0; i < pubs_count; i++) {
ge_p2 tmp2;
ge_p3 tmp3;
if (i == sec_index) {
random_scalar(k);
ge_scalarmult_base(&tmp3, &k);
ge_p3_tobytes(&buf->ab[i].a, &tmp3);
hash_to_ec(*pubs[i], tmp3);
ge_scalarmult(&tmp2, &k, &tmp3);
ge_tobytes(&buf->ab[i].b, &tmp2);
} else {
random_scalar(sig[i].c);
random_scalar(sig[i].r);
if (ge_frombytes_vartime(&tmp3, &*pubs[i]) != 0) {
abort();
}
ge_double_scalarmult_base_vartime(&tmp2, &sig[i].c, &tmp3, &sig[i].r);
ge_tobytes(&buf->ab[i].a, &tmp2);
hash_to_ec(*pubs[i], tmp3);
ge_double_scalarmult_precomp_vartime(&tmp2, &sig[i].r, &tmp3, &sig[i].c, image_pre);
ge_tobytes(&buf->ab[i].b, &tmp2);
sc_add(&sum, &sum, &sig[i].c);
}
}
hash_to_scalar(buf, rs_comm_size(pubs_count), h);
sc_sub(&sig[sec_index].c, &h, &sum);
sc_mulsub(&sig[sec_index].r, &sig[sec_index].c, &sec, &k);
}
bool crypto_ops::check_ring_signature(const hash &prefix_hash, const key_image &image,
const public_key *const *pubs, size_t pubs_count,
const signature *sig) {
size_t i;
ge_p3 image_unp;
ge_dsmp image_pre;
ec_scalar sum, h;
rs_comm *const buf = reinterpret_cast<rs_comm *>(alloca(rs_comm_size(pubs_count)));
#if !defined(NDEBUG)
for (i = 0; i < pubs_count; i++) {
assert(check_key(*pubs[i]));
}
#endif
if (ge_frombytes_vartime(&image_unp, &image) != 0) {
return false;
}
ge_dsm_precomp(image_pre, &image_unp);
sc_0(&sum);
buf->h = prefix_hash;
for (i = 0; i < pubs_count; i++) {
ge_p2 tmp2;
ge_p3 tmp3;
if (sc_check(&sig[i].c) != 0 || sc_check(&sig[i].r) != 0) {
return false;
}
if (ge_frombytes_vartime(&tmp3, &*pubs[i]) != 0) {
return false;
}
ge_double_scalarmult_base_vartime(&tmp2, &sig[i].c, &tmp3, &sig[i].r);
ge_tobytes(&buf->ab[i].a, &tmp2);
hash_to_ec(*pubs[i], tmp3);
ge_double_scalarmult_precomp_vartime(&tmp2, &sig[i].r, &tmp3, &sig[i].c, image_pre);
ge_tobytes(&buf->ab[i].b, &tmp2);
sc_add(&sum, &sum, &sig[i].c);
}
hash_to_scalar(buf, rs_comm_size(pubs_count), h);
sc_sub(&h, &h, &sum);
return sc_isnonzero(&h) == 0;
}
}
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