/*********************************************************************** * Copyright (c) 2013-2015 Pieter Wuille * * Distributed under the MIT software license, see the accompanying * * file COPYING or https://www.opensource.org/licenses/mit-license.php.* ***********************************************************************/ #ifndef SECP256K1_TESTRAND_IMPL_H #define SECP256K1_TESTRAND_IMPL_H #include #include #include #include "testrand.h" #include "hash.h" static rustsecp256k1_v0_4_1_rfc6979_hmac_sha256 rustsecp256k1_v0_4_1_test_rng; static uint32_t rustsecp256k1_v0_4_1_test_rng_precomputed[8]; static int rustsecp256k1_v0_4_1_test_rng_precomputed_used = 8; static uint64_t rustsecp256k1_v0_4_1_test_rng_integer; static int rustsecp256k1_v0_4_1_test_rng_integer_bits_left = 0; SECP256K1_INLINE static void rustsecp256k1_v0_4_1_testrand_seed(const unsigned char *seed16) { rustsecp256k1_v0_4_1_rfc6979_hmac_sha256_initialize(&rustsecp256k1_v0_4_1_test_rng, seed16, 16); } SECP256K1_INLINE static uint32_t rustsecp256k1_v0_4_1_testrand32(void) { if (rustsecp256k1_v0_4_1_test_rng_precomputed_used == 8) { rustsecp256k1_v0_4_1_rfc6979_hmac_sha256_generate(&rustsecp256k1_v0_4_1_test_rng, (unsigned char*)(&rustsecp256k1_v0_4_1_test_rng_precomputed[0]), sizeof(rustsecp256k1_v0_4_1_test_rng_precomputed)); rustsecp256k1_v0_4_1_test_rng_precomputed_used = 0; } return rustsecp256k1_v0_4_1_test_rng_precomputed[rustsecp256k1_v0_4_1_test_rng_precomputed_used++]; } static uint32_t rustsecp256k1_v0_4_1_testrand_bits(int bits) { uint32_t ret; if (rustsecp256k1_v0_4_1_test_rng_integer_bits_left < bits) { rustsecp256k1_v0_4_1_test_rng_integer |= (((uint64_t)rustsecp256k1_v0_4_1_testrand32()) << rustsecp256k1_v0_4_1_test_rng_integer_bits_left); rustsecp256k1_v0_4_1_test_rng_integer_bits_left += 32; } ret = rustsecp256k1_v0_4_1_test_rng_integer; rustsecp256k1_v0_4_1_test_rng_integer >>= bits; rustsecp256k1_v0_4_1_test_rng_integer_bits_left -= bits; ret &= ((~((uint32_t)0)) >> (32 - bits)); return ret; } static uint32_t rustsecp256k1_v0_4_1_testrand_int(uint32_t range) { /* We want a uniform integer between 0 and range-1, inclusive. * B is the smallest number such that range <= 2**B. * two mechanisms implemented here: * - generate B bits numbers until one below range is found, and return it * - find the largest multiple M of range that is <= 2**(B+A), generate B+A * bits numbers until one below M is found, and return it modulo range * The second mechanism consumes A more bits of entropy in every iteration, * but may need fewer iterations due to M being closer to 2**(B+A) then * range is to 2**B. The array below (indexed by B) contains a 0 when the * first mechanism is to be used, and the number A otherwise. */ static const int addbits[] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 2, 1, 0}; uint32_t trange, mult; int bits = 0; if (range <= 1) { return 0; } trange = range - 1; while (trange > 0) { trange >>= 1; bits++; } if (addbits[bits]) { bits = bits + addbits[bits]; mult = ((~((uint32_t)0)) >> (32 - bits)) / range; trange = range * mult; } else { trange = range; mult = 1; } while(1) { uint32_t x = rustsecp256k1_v0_4_1_testrand_bits(bits); if (x < trange) { return (mult == 1) ? x : (x % range); } } } static void rustsecp256k1_v0_4_1_testrand256(unsigned char *b32) { rustsecp256k1_v0_4_1_rfc6979_hmac_sha256_generate(&rustsecp256k1_v0_4_1_test_rng, b32, 32); } static void rustsecp256k1_v0_4_1_testrand_bytes_test(unsigned char *bytes, size_t len) { size_t bits = 0; memset(bytes, 0, len); while (bits < len * 8) { int now; uint32_t val; now = 1 + (rustsecp256k1_v0_4_1_testrand_bits(6) * rustsecp256k1_v0_4_1_testrand_bits(5) + 16) / 31; val = rustsecp256k1_v0_4_1_testrand_bits(1); while (now > 0 && bits < len * 8) { bytes[bits / 8] |= val << (bits % 8); now--; bits++; } } } static void rustsecp256k1_v0_4_1_testrand256_test(unsigned char *b32) { rustsecp256k1_v0_4_1_testrand_bytes_test(b32, 32); } static void rustsecp256k1_v0_4_1_testrand_flip(unsigned char *b, size_t len) { b[rustsecp256k1_v0_4_1_testrand_int(len)] ^= (1 << rustsecp256k1_v0_4_1_testrand_int(8)); } static void rustsecp256k1_v0_4_1_testrand_init(const char* hexseed) { unsigned char seed16[16] = {0}; if (hexseed && strlen(hexseed) != 0) { int pos = 0; while (pos < 16 && hexseed[0] != 0 && hexseed[1] != 0) { unsigned short sh; if ((sscanf(hexseed, "%2hx", &sh)) == 1) { seed16[pos] = sh; } else { break; } hexseed += 2; pos++; } } else { FILE *frand = fopen("/dev/urandom", "rb"); if ((frand == NULL) || fread(&seed16, 1, sizeof(seed16), frand) != sizeof(seed16)) { uint64_t t = time(NULL) * (uint64_t)1337; fprintf(stderr, "WARNING: could not read 16 bytes from /dev/urandom; falling back to insecure PRNG\n"); seed16[0] ^= t; seed16[1] ^= t >> 8; seed16[2] ^= t >> 16; seed16[3] ^= t >> 24; seed16[4] ^= t >> 32; seed16[5] ^= t >> 40; seed16[6] ^= t >> 48; seed16[7] ^= t >> 56; } if (frand) { fclose(frand); } } printf("random seed = %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n", seed16[0], seed16[1], seed16[2], seed16[3], seed16[4], seed16[5], seed16[6], seed16[7], seed16[8], seed16[9], seed16[10], seed16[11], seed16[12], seed16[13], seed16[14], seed16[15]); rustsecp256k1_v0_4_1_testrand_seed(seed16); } static void rustsecp256k1_v0_4_1_testrand_finish(void) { unsigned char run32[32]; rustsecp256k1_v0_4_1_testrand256(run32); printf("random run = %02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x\n", run32[0], run32[1], run32[2], run32[3], run32[4], run32[5], run32[6], run32[7], run32[8], run32[9], run32[10], run32[11], run32[12], run32[13], run32[14], run32[15]); } #endif /* SECP256K1_TESTRAND_IMPL_H */