diff options
| -rw-r--r-- | src/crypto/crypto.cpp | 28 | ||||
| -rw-r--r-- | src/crypto/crypto.h | 1 | ||||
| -rw-r--r-- | src/ringct/rctOps.cpp | 10 | ||||
| -rw-r--r-- | tests/unit_tests/CMakeLists.txt | 1 | ||||
| -rw-r--r-- | tests/unit_tests/random.cpp | 47 |
5 files changed, 77 insertions, 10 deletions
diff --git a/src/crypto/crypto.cpp b/src/crypto/crypto.cpp index 0fd6d9363..0c019938d 100644 --- a/src/crypto/crypto.cpp +++ b/src/crypto/crypto.cpp @@ -93,12 +93,32 @@ namespace crypto { generate_random_bytes_not_thread_safe(N, bytes); } + static inline bool less32(const unsigned char *k0, const unsigned char *k1) + { + for (int n = 31; n >= 0; --n) + { + if (k0[n] < k1[n]) + return true; + if (k0[n] > k1[n]) + return false; + } + return false; + } + + void random32_unbiased(unsigned char *bytes) + { + // l = 2^252 + 27742317777372353535851937790883648493. + // it fits 15 in 32 bytes + static const unsigned char limit[32] = { 0xe3, 0x6a, 0x67, 0x72, 0x8b, 0xce, 0x13, 0x29, 0x8f, 0x30, 0x82, 0x8c, 0x0b, 0xa4, 0x10, 0x39, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xf0 }; + do + { + generate_random_bytes_thread_safe(32, bytes); + } while (!less32(bytes, limit)); // should be good about 15/16 of the time + sc_reduce32(bytes); + } /* 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_thread_safe(64, tmp); - sc_reduce(tmp); - memcpy(&res, tmp, 32); + random32_unbiased((unsigned char*)res.data); } void hash_to_scalar(const void *data, size_t length, ec_scalar &res) { diff --git a/src/crypto/crypto.h b/src/crypto/crypto.h index 9ea0f2ec0..449af8f6d 100644 --- a/src/crypto/crypto.h +++ b/src/crypto/crypto.h @@ -99,6 +99,7 @@ namespace crypto { #pragma pack(pop) void hash_to_scalar(const void *data, size_t length, ec_scalar &res); + void random32_unbiased(unsigned char *bytes); static_assert(sizeof(ec_point) == 32 && sizeof(ec_scalar) == 32 && sizeof(public_key) == 32 && sizeof(secret_key) == 32 && diff --git a/src/ringct/rctOps.cpp b/src/ringct/rctOps.cpp index 68cc43128..50693bad7 100644 --- a/src/ringct/rctOps.cpp +++ b/src/ringct/rctOps.cpp @@ -62,14 +62,13 @@ namespace rct { //generates a random scalar which can be used as a secret key or mask void skGen(key &sk) { - sk = crypto::rand<key>(); - sc_reduce32(sk.bytes); + random32_unbiased(sk.bytes); } //generates a random scalar which can be used as a secret key or mask key skGen() { - key sk = crypto::rand<key>(); - sc_reduce32(sk.bytes); + key sk; + skGen(sk); return sk; } @@ -79,9 +78,8 @@ namespace rct { CHECK_AND_ASSERT_THROW_MES(rows > 0, "0 keys requested"); keyV rv(rows); size_t i = 0; - crypto::rand(rows * sizeof(key), (uint8_t*)&rv[0]); for (i = 0 ; i < rows ; i++) { - sc_reduce32(rv[i].bytes); + skGen(rv[i]); } return rv; } diff --git a/tests/unit_tests/CMakeLists.txt b/tests/unit_tests/CMakeLists.txt index ffa8065ab..3c7414640 100644 --- a/tests/unit_tests/CMakeLists.txt +++ b/tests/unit_tests/CMakeLists.txt @@ -56,6 +56,7 @@ set(unit_tests_sources mul_div.cpp multisig.cpp parse_amount.cpp + random.cpp serialization.cpp sha256.cpp slow_memmem.cpp diff --git a/tests/unit_tests/random.cpp b/tests/unit_tests/random.cpp new file mode 100644 index 000000000..7653453cd --- /dev/null +++ b/tests/unit_tests/random.cpp @@ -0,0 +1,47 @@ +// Copyright (c) 2018, 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 "gtest/gtest.h" + +#include "crypto/crypto.h" + +extern "C" { +#include "crypto/crypto-ops.h" +} + +TEST(random32_unbiased, less_than_order) +{ + unsigned char tmp[32], tmp2[32]; + for (int i = 0; i < 1000; ++i) + { + crypto::random32_unbiased(tmp); + memcpy(tmp2, tmp, 32); + sc_reduce32(tmp2); + ASSERT_EQ(memcmp(tmp, tmp2, 32), 0); + } +} |