3 This file is part of the ARM-Crypto-Lib.
4 Copyright (C) 2006-2010 Daniel Otte (daniel.otte@rub.de)
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation, either version 3 of the License, or
9 (at your option) any later version.
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
24 #include "hfal-basic.h"
26 uint8_t dsa_verify_bigint(const dsa_signature_t* s, const bigint_t* m,
27 const dsa_ctx_t* ctx){
28 if(s->r.length_W==0 || s->s.length_W==0){
29 return DSA_SIGNATURE_FAIL;
31 if(bigint_cmp_u(&(s->r), &(ctx->domain.q))>=0 || bigint_cmp_u(&(s->s), &(ctx->domain.q))>=0){
32 return DSA_SIGNATURE_FAIL;
34 bigint_t w, u1, u2, v1, v2;
35 bigint_word_t w_b[ctx->domain.q.length_W], u1_b[ctx->domain.q.length_W*2], u2_b[ctx->domain.q.length_W*2];
36 bigint_word_t v1_b[ctx->domain.p.length_W*2], v2_b[ctx->domain.p.length_W];
42 bigint_inverse(&w, &(s->s), &(ctx->domain.q));
43 bigint_mul_u(&u1, &w, m);
44 bigint_reduce(&u1, &(ctx->domain.q));
45 bigint_mul_u(&u2, &w, &(s->r));
46 bigint_reduce(&u2, &(ctx->domain.q));
47 bigint_expmod_u(&v1, &(ctx->domain.g), &u1, &(ctx->domain.p));
48 bigint_expmod_u(&v2, &(ctx->pub), &u2, &(ctx->domain.p));
49 bigint_mul_u(&v1, &v1, &v2);
50 bigint_reduce(&v1, &(ctx->domain.p));
51 bigint_reduce(&v1, &(ctx->domain.q));
52 if(bigint_cmp_u(&v1, &(s->r))==0){
53 return DSA_SIGNATURE_OK;
55 return DSA_SIGNATURE_FAIL;
58 uint8_t dsa_verify_message(const dsa_signature_t* s, const void* m, uint16_t m_len_b,
59 const hfdesc_t* hash_desc, const dsa_ctx_t* ctx){
61 uint16_t n_B = ctx->domain.q.length_W;
62 unsigned hash_length = (hfal_hash_getHashsize(hash_desc)+sizeof(bigint_word_t)*8-1)/(sizeof(bigint_word_t)*8);
63 bigint_word_t hash_value[hash_length];
64 memset(hash_value, 0, hash_length*sizeof(bigint_word_t));
65 hfal_hash_mem(hash_desc, hash_value, m, m_len_b);
68 bigint_changeendianess(&z);
70 return dsa_verify_bigint(s, &z, ctx);