1 /**********************************************************************
3 * Copyright (c) 2005-2006 Cryptocom LTD *
4 * This file is distributed under the same license as OpenSSL *
6 * Implementation of GOST R 34.10-94 signature algorithm *
8 * Requires OpenSSL 0.9.9 for compilation *
9 **********************************************************************/
11 #include <openssl/rand.h>
12 #include <openssl/bn.h>
13 #include <openssl/dsa.h>
14 #include <openssl/evp.h>
16 #include "gost_params.h"
18 #include "e_gost_err.h"
21 void dump_signature(const char *message, const unsigned char *buffer,
25 fprintf(stderr, "signature %s Length=%d", message, len);
26 for (i = 0; i < len; i++) {
29 fprintf(stderr, " %02x", buffer[i]);
31 fprintf(stderr, "\nEnd of signature\n");
34 void dump_dsa_sig(const char *message, DSA_SIG *sig)
36 fprintf(stderr, "%s\nR=", message);
37 BN_print_fp(stderr, sig->r);
38 fprintf(stderr, "\nS=");
39 BN_print_fp(stderr, sig->s);
40 fprintf(stderr, "\n");
45 # define dump_signature(a,b,c)
46 # define dump_dsa_sig(a,b)
50 * Computes signature and returns it as DSA_SIG structure
52 DSA_SIG *gost_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
54 BIGNUM *k = NULL, *tmp = NULL, *tmp2 = NULL;
55 DSA_SIG *newsig = DSA_SIG_new();
56 BIGNUM *md = hashsum2bn(dgst);
57 /* check if H(M) mod q is zero */
58 BN_CTX *ctx = BN_CTX_new();
61 GOSTerr(GOST_F_GOST_DO_SIGN, GOST_R_NO_MEMORY);
64 tmp = BN_CTX_get(ctx);
66 tmp2 = BN_CTX_get(ctx);
67 BN_mod(tmp, md, dsa->q, ctx);
68 if (BN_is_zero(tmp)) {
74 * Generate random number k less than q
76 BN_rand_range(k, dsa->q);
77 /* generate r = (a^x mod p) mod q */
78 BN_mod_exp(tmp, dsa->g, k, dsa->p, ctx);
81 BN_mod(newsig->r, tmp, dsa->q, ctx);
83 while (BN_is_zero(newsig->r));
84 /* generate s = (xr + k(Hm)) mod q */
85 BN_mod_mul(tmp, dsa->priv_key, newsig->r, dsa->q, ctx);
86 BN_mod_mul(tmp2, k, md, dsa->q, ctx);
89 BN_mod_add(newsig->s, tmp, tmp2, dsa->q, ctx);
91 while (BN_is_zero(newsig->s));
100 * Packs signature according to Cryptocom rules
101 * and frees up DSA_SIG structure
104 int pack_sign_cc(DSA_SIG *s,int order,unsigned char *sig, size_t *siglen)
107 memset(sig,0,*siglen);
108 store_bignum(s->r, sig,order);
109 store_bignum(s->s, sig + order,order);
110 dump_signature("serialized",sig,*siglen);
116 * Packs signature according to Cryptopro rules
117 * and frees up DSA_SIG structure
119 int pack_sign_cp(DSA_SIG *s, int order, unsigned char *sig, size_t *siglen)
122 memset(sig, 0, *siglen);
123 store_bignum(s->s, sig, order);
124 store_bignum(s->r, sig + order, order);
125 dump_signature("serialized", sig, *siglen);
131 * Verifies signature passed as DSA_SIG structure
135 int gost_do_verify(const unsigned char *dgst, int dgst_len,
136 DSA_SIG *sig, DSA *dsa)
138 BIGNUM *md, *tmp = NULL;
140 BIGNUM *u = NULL, *v = NULL, *z1 = NULL, *z2 = NULL;
141 BIGNUM *tmp2 = NULL, *tmp3 = NULL;
143 BN_CTX *ctx = BN_CTX_new();
146 if (BN_cmp(sig->s, dsa->q) >= 1 || BN_cmp(sig->r, dsa->q) >= 1) {
147 GOSTerr(GOST_F_GOST_DO_VERIFY, GOST_R_SIGNATURE_PARTS_GREATER_THAN_Q);
150 md = hashsum2bn(dgst);
152 tmp = BN_CTX_get(ctx);
154 q2 = BN_CTX_get(ctx);
155 z1 = BN_CTX_get(ctx);
156 z2 = BN_CTX_get(ctx);
157 tmp2 = BN_CTX_get(ctx);
158 tmp3 = BN_CTX_get(ctx);
161 BN_mod(tmp, md, dsa->q, ctx);
162 if (BN_is_zero(tmp)) {
167 BN_mod_exp(v, md, q2, dsa->q, ctx);
168 BN_mod_mul(z1, sig->s, v, dsa->q, ctx);
169 BN_sub(tmp, dsa->q, sig->r);
170 BN_mod_mul(z2, tmp, v, dsa->p, ctx);
171 BN_mod_exp(tmp, dsa->g, z1, dsa->p, ctx);
172 BN_mod_exp(tmp2, dsa->pub_key, z2, dsa->p, ctx);
173 BN_mod_mul(tmp3, tmp, tmp2, dsa->p, ctx);
174 BN_mod(u, tmp3, dsa->q, ctx);
175 ok = BN_cmp(u, sig->r);
181 GOSTerr(GOST_F_GOST_DO_VERIFY, GOST_R_SIGNATURE_MISMATCH);
187 * Computes public keys for GOST R 34.10-94 algorithm
190 int gost94_compute_public(DSA *dsa)
192 /* Now fill algorithm parameters with correct values */
193 BN_CTX *ctx = BN_CTX_new();
195 GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC, GOST_R_KEY_IS_NOT_INITALIZED);
198 /* Compute public key y = a^x mod p */
199 dsa->pub_key = BN_new();
200 BN_mod_exp(dsa->pub_key, dsa->g, dsa->priv_key, dsa->p, ctx);
206 * Fill GOST 94 params, searching them in R3410_paramset array
210 int fill_GOST94_params(DSA *dsa, int nid)
212 R3410_params *params = R3410_paramset;
213 while (params->nid != NID_undef && params->nid != nid)
215 if (params->nid == NID_undef) {
216 GOSTerr(GOST_F_FILL_GOST94_PARAMS, GOST_R_UNSUPPORTED_PARAMETER_SET);
219 #define dump_signature(a,b,c)
224 BN_dec2bn(&(dsa->p), params->p);
229 BN_dec2bn(&(dsa->q), params->q);
234 BN_dec2bn(&(dsa->g), params->a);
239 * Generate GOST R 34.10-94 keypair
243 int gost_sign_keygen(DSA *dsa)
245 dsa->priv_key = BN_new();
246 BN_rand_range(dsa->priv_key, dsa->q);
247 return gost94_compute_public(dsa);
250 /* Unpack signature according to cryptocom rules */
252 DSA_SIG *unpack_cc_signature(const unsigned char *sig,size_t siglen)
258 GOSTerr(GOST_F_UNPACK_CC_SIGNATURE,GOST_R_NO_MEMORY);
261 s->r = getbnfrombuf(sig, siglen/2);
262 s->s = getbnfrombuf(sig + siglen/2, siglen/2);
266 /* Unpack signature according to cryptopro rules */
267 DSA_SIG *unpack_cp_signature(const unsigned char *sig, size_t siglen)
273 GOSTerr(GOST_F_UNPACK_CP_SIGNATURE, GOST_R_NO_MEMORY);
276 s->s = getbnfrombuf(sig, siglen / 2);
277 s->r = getbnfrombuf(sig + siglen / 2, siglen / 2);
281 /* Convert little-endian byte array into bignum */
282 BIGNUM *hashsum2bn(const unsigned char *dgst)
284 unsigned char buf[32];
286 for (i = 0; i < 32; i++) {
287 buf[31 - i] = dgst[i];
289 return getbnfrombuf(buf, 32);
292 /* Convert byte buffer to bignum, skipping leading zeros*/
293 BIGNUM *getbnfrombuf(const unsigned char *buf, size_t len)
295 while (*buf == 0 && len > 0) {
300 return BN_bin2bn(buf, len, NULL);
302 BIGNUM *b = BN_new();
309 * Pack bignum into byte buffer of given size, filling all leading bytes by
312 int store_bignum(BIGNUM *bn, unsigned char *buf, int len)
314 int bytes = BN_num_bytes(bn);
318 BN_bn2bin(bn, buf + len - bytes);