/** * Copyright (c) 2013-2014 Tomas Dzetkulic * Copyright (c) 2013-2014 Pavol Rusnak * Copyright (c) 2015 Jochen Hoenicke * * Permission is hereby granted, free of charge, to any person obtaining * a copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included * in all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES * OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. */ #include <assert.h> #include "hmac_drbg.h" #include "memzero.h" #include "rfc6979.h" void init_rfc6979(const uint8_t *priv_key, const uint8_t *hash, const ecdsa_curve *curve, rfc6979_state *state) { if (curve) { bignum256 hash_bn = {0}; bn_read_be(hash, &hash_bn); // Make sure hash is partly reduced modulo order assert(bn_bitcount(&curve->order) >= 256); bn_mod(&hash_bn, &curve->order); uint8_t hash_reduced[32] = {0}; bn_write_be(&hash_bn, hash_reduced); memzero(&hash_bn, sizeof(hash_bn)); hmac_drbg_init(state, priv_key, 32, hash_reduced, 32); memzero(hash_reduced, sizeof(hash_reduced)); } else { hmac_drbg_init(state, priv_key, 32, hash, 32); } } // generate next number from deterministic random number generator void generate_rfc6979(uint8_t rnd[32], rfc6979_state *state) { hmac_drbg_generate(state, rnd, 32); } // generate K in a deterministic way, according to RFC6979 // http://tools.ietf.org/html/rfc6979 void generate_k_rfc6979(bignum256 *k, rfc6979_state *state) { uint8_t buf[32] = {0}; generate_rfc6979(buf, state); bn_read_be(buf, k); memzero(buf, sizeof(buf)); }