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