--- /dev/null
+/* dsa_verify.c */
+/*
+ This file is part of the AVR-Crypto-Lib.
+ Copyright (C) 2010 Daniel Otte (daniel.otte@rub.de)
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation, either version 3 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <stdint.h>
+#include "bigint.h"
+#include "dsa.h"
+#include "hfal-basic.h"
+
+uint8_t dsa_verify_bigint(const dsa_signature_t* s, const bigint_t* m,
+ const dsa_ctx_t* ctx){
+ if(s->r.length_B==0 || s->s.length_B==0){
+ return DSA_SIGNATURE_FAIL;
+ }
+ if(bigint_cmp_u(&(s->r), &(ctx->domain.q))>=0 || bigint_cmp_u(&(s->s), &(ctx->domain.q))>=0){
+ return DSA_SIGNATURE_FAIL;
+ }
+ bigint_t w, u1, u2, v1, v2;
+ uint8_t w_b[ctx->domain.q.length_B], u1_b[ctx->domain.q.length_B*2], u2_b[ctx->domain.q.length_B*2];
+ uint8_t v1_b[ctx->domain.p.length_B*2], v2_b[ctx->domain.p.length_B];
+ w.wordv = w_b;
+ u1.wordv = u1_b;
+ u2.wordv = u2_b;
+ v1.wordv = v1_b;
+ v2.wordv = v2_b;
+ bigint_inverse(&w, &(s->s), &(ctx->domain.q));
+ bigint_mul_u(&u1, &w, m);
+ bigint_reduce(&u1, &(ctx->domain.q));
+ bigint_mul_u(&u2, &w, &(s->r));
+ bigint_reduce(&u2, &(ctx->domain.q));
+ bigint_expmod_u(&v1, &(ctx->domain.g), &u1, &(ctx->domain.p));
+ bigint_expmod_u(&v2, &(ctx->pub), &u2, &(ctx->domain.p));
+ bigint_mul_u(&v1, &v1, &v2);
+ bigint_reduce(&v1, &(ctx->domain.p));
+ bigint_reduce(&v1, &(ctx->domain.q));
+ if(bigint_cmp_u(&v1, &(s->r))==0){
+ return DSA_SIGNATURE_OK;
+ }
+ return DSA_SIGNATURE_FAIL;
+}
+
+uint8_t dsa_verify_message(const dsa_signature_t* s, const void* m, uint16_t m_len_b,
+ const hfdesc_t* hash_desc, const dsa_ctx_t* ctx){
+ bigint_t z;
+ uint8_t n_B = ctx->domain.q.length_B;
+ uint8_t hash_value[(hfal_hash_getHashsize(hash_desc)+7)/8];
+ hfal_hash_mem(hash_desc, hash_value, m, m_len_b);
+ z.wordv=hash_value;
+ z.length_B=n_B;
+ bigint_changeendianess(&z);
+ bigint_adjust(&z);
+ return dsa_verify_bigint(s, &z, ctx);
+}
+
+
+
+
+
+
+