stack usage measurement

[avr-crypto-lib.git] / dsa / dsa_verify.c

diff --git a/dsa/dsa_verify.c b/dsa/dsa_verify.c
new file mode 100644 (file)
index 0000000..1faa68e
--- /dev/null
+++ b/dsa/dsa_verify.c
@@ -0,0 +1,75 @@
+/* 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);
+}
+
+
+
+
+
+
+