77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
/* dsa_sign.c */
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/*
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This file is part of the ARM-Crypto-Lib.
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Copyright (C) 2006-2010 Daniel Otte (daniel.otte@rub.de)
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdint.h>
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#include <string.h>
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#include "bigint.h"
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#include "dsa.h"
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#include "hashfunction_descriptor.h"
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#include "hfal-basic.h"
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#define MAX(a,b) (((a)>(b))?(a):(b))
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uint8_t dsa_sign_bigint(dsa_signature_t* s, const bigint_t* m,
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const dsa_ctx_t* ctx, const bigint_t* k){
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bigint_t tmp, tmp2;
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bigint_word_t tmp_b[ctx->domain.p.length_W+5], tmp2_b[ctx->domain.q.length_W+5];
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tmp.wordv= tmp_b;
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tmp2.wordv = tmp2_b;
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bigint_expmod_u(&tmp, &(ctx->domain.g), k, &(ctx->domain.p));
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bigint_reduce(&tmp, &(ctx->domain.q));
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bigint_copy(&(s->r), &tmp);
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bigint_mul_u(&tmp, &tmp, &(ctx->priv));
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bigint_add_u(&tmp, &tmp, m);
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bigint_inverse(&tmp2, k, &(ctx->domain.q));
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bigint_mul_u(&tmp, &tmp, &tmp2);
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bigint_reduce(&tmp, &(ctx->domain.q));
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bigint_copy(&(s->s), &tmp);
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if(s->s.length_W==0 || s->r.length_W==0){
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return 1;
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}
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return 0;
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}
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uint8_t dsa_sign_message(dsa_signature_t* s, const void* m, uint16_t m_len_b,
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const hfdesc_t* hash_desc, const dsa_ctx_t* ctx,
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uint8_t(*rand_in)(void)){
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bigint_t z, k;
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uint16_t i, n_B = ctx->domain.q.length_W;
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unsigned hash_length = MAX(n_B,(hfal_hash_getHashsize(hash_desc)+sizeof(bigint_word_t)*8-1)/(sizeof(bigint_word_t)*8));
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bigint_word_t hash_value[hash_length];
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bigint_word_t k_b[n_B];
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memset(hash_value, 0, hash_length*sizeof(bigint_word_t));
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hfal_hash_mem(hash_desc, hash_value, m, m_len_b);
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z.wordv = hash_value;
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z.length_W = n_B;
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bigint_changeendianess(&z);
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k.wordv = k_b;
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k.length_W = n_B;
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do{
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for(i=0; i<n_B*sizeof(bigint_word_t); ++i){
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((uint8_t*)k_b)[i] = rand_in();
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}
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k.length_W = n_B;
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bigint_adjust(&k);
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}while(dsa_sign_bigint(s, &z, ctx, &k));
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return 0;
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}
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