aboutsummaryrefslogtreecommitdiff
path: root/openssl/engines/ccgost/gost_sign.c
blob: 07ad921ab530fd585168fbb2c0659e29d33ca897 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
/**********************************************************************
 *                          gost_sign.c                               *
 *             Copyright (c) 2005-2006 Cryptocom LTD                  *
 *         This file is distributed under the same license as OpenSSL *
 *                                                                    *
 *       Implementation of GOST R 34.10-94 signature algorithm        *
 *       for OpenSSL                                                  *
 *          Requires OpenSSL 0.9.9 for compilation                    *
 **********************************************************************/
#include <string.h>
#include <openssl/rand.h>
#include <openssl/bn.h>
#include <openssl/dsa.h>
#include <openssl/evp.h>
#include <openssl/err.h>

#include "gost_params.h"
#include "gost_lcl.h"
#include "e_gost_err.h"

#ifdef DEBUG_SIGN
void dump_signature(const char *message, const unsigned char *buffer,
                    size_t len)
{
    size_t i;
    fprintf(stderr, "signature %s Length=%d", message, len);
    for (i = 0; i < len; i++) {
        if (i % 16 == 0)
            fputc('\n', stderr);
        fprintf(stderr, " %02x", buffer[i]);
    }
    fprintf(stderr, "\nEnd of signature\n");
}

void dump_dsa_sig(const char *message, DSA_SIG *sig)
{
    fprintf(stderr, "%s\nR=", message);
    BN_print_fp(stderr, sig->r);
    fprintf(stderr, "\nS=");
    BN_print_fp(stderr, sig->s);
    fprintf(stderr, "\n");
}

#else

# define dump_signature(a,b,c)
# define dump_dsa_sig(a,b)
#endif

/*
 * Computes signature and returns it as DSA_SIG structure
 */
DSA_SIG *gost_do_sign(const unsigned char *dgst, int dlen, DSA *dsa)
{
    BIGNUM *k = NULL, *tmp = NULL, *tmp2 = NULL;
    DSA_SIG *newsig = NULL, *ret = NULL;
    BIGNUM *md = hashsum2bn(dgst);
    /* check if H(M) mod q is zero */
    BN_CTX *ctx = BN_CTX_new();
    if(!ctx) {
        GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    BN_CTX_start(ctx);
    newsig = DSA_SIG_new();
    if (!newsig) {
        GOSTerr(GOST_F_GOST_DO_SIGN, GOST_R_NO_MEMORY);
        goto err;
    }
    tmp = BN_CTX_get(ctx);
    k = BN_CTX_get(ctx);
    tmp2 = BN_CTX_get(ctx);
    if(!tmp || !k || !tmp2) {
        GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
        goto err;
    }
    BN_mod(tmp, md, dsa->q, ctx);
    if (BN_is_zero(tmp)) {
        BN_one(md);
    }
    do {
        do {
            /*
             * Generate random number k less than q
             */
            BN_rand_range(k, dsa->q);
            /* generate r = (a^x mod p) mod q */
            BN_mod_exp(tmp, dsa->g, k, dsa->p, ctx);
            if (!(newsig->r)) {
                newsig->r = BN_new();
                if(!newsig->r) {
                    GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
                    goto err;
                }
            }
            BN_mod(newsig->r, tmp, dsa->q, ctx);
        }
        while (BN_is_zero(newsig->r));
        /* generate s = (xr + k(Hm)) mod q */
        BN_mod_mul(tmp, dsa->priv_key, newsig->r, dsa->q, ctx);
        BN_mod_mul(tmp2, k, md, dsa->q, ctx);
        if (!newsig->s) {
            newsig->s = BN_new();
            if(!newsig->s) {
                GOSTerr(GOST_F_GOST_DO_SIGN, ERR_R_MALLOC_FAILURE);
                goto err;
            }
        }
        BN_mod_add(newsig->s, tmp, tmp2, dsa->q, ctx);
    }
    while (BN_is_zero(newsig->s));

    ret = newsig;
 err:
    BN_free(md);
    if(ctx) {
        BN_CTX_end(ctx);
        BN_CTX_free(ctx);
    }
    if(!ret && newsig) {
        DSA_SIG_free(newsig);
    }
    return ret;
}

/*
 * Packs signature according to Cryptocom rules
 * and frees up DSA_SIG structure
 */
/*-
int pack_sign_cc(DSA_SIG *s,int order,unsigned char *sig, size_t *siglen)
        {
        *siglen = 2*order;
        memset(sig,0,*siglen);
        store_bignum(s->r, sig,order);
        store_bignum(s->s, sig + order,order);
        dump_signature("serialized",sig,*siglen);
        DSA_SIG_free(s);
        return 1;
        }
*/
/*
 * Packs signature according to Cryptopro rules
 * and frees up DSA_SIG structure
 */
int pack_sign_cp(DSA_SIG *s, int order, unsigned char *sig, size_t *siglen)
{
    *siglen = 2 * order;
    memset(sig, 0, *siglen);
    store_bignum(s->s, sig, order);
    store_bignum(s->r, sig + order, order);
    dump_signature("serialized", sig, *siglen);
    DSA_SIG_free(s);
    return 1;
}

/*
 * Verifies signature passed as DSA_SIG structure
 *
 */

int gost_do_verify(const unsigned char *dgst, int dgst_len,
                   DSA_SIG *sig, DSA *dsa)
{
    BIGNUM *md = NULL, *tmp = NULL;
    BIGNUM *q2 = NULL;
    BIGNUM *u = NULL, *v = NULL, *z1 = NULL, *z2 = NULL;
    BIGNUM *tmp2 = NULL, *tmp3 = NULL;
    int ok = 0;
    BN_CTX *ctx = BN_CTX_new();
    if(!ctx) {
        GOSTerr(GOST_F_GOST_DO_VERIFY, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    BN_CTX_start(ctx);
    if (BN_cmp(sig->s, dsa->q) >= 1 || BN_cmp(sig->r, dsa->q) >= 1) {
        GOSTerr(GOST_F_GOST_DO_VERIFY, GOST_R_SIGNATURE_PARTS_GREATER_THAN_Q);
        goto err;
    }
    md = hashsum2bn(dgst);

    tmp = BN_CTX_get(ctx);
    v = BN_CTX_get(ctx);
    q2 = BN_CTX_get(ctx);
    z1 = BN_CTX_get(ctx);
    z2 = BN_CTX_get(ctx);
    tmp2 = BN_CTX_get(ctx);
    tmp3 = BN_CTX_get(ctx);
    u = BN_CTX_get(ctx);
    if(!tmp || !v || !q2 || !z1 || !z2 || !tmp2 || !tmp3 || !u) {
        GOSTerr(GOST_F_GOST_DO_VERIFY, ERR_R_MALLOC_FAILURE);
        goto err;
    }

    BN_mod(tmp, md, dsa->q, ctx);
    if (BN_is_zero(tmp)) {
        BN_one(md);
    }
    BN_copy(q2, dsa->q);
    BN_sub_word(q2, 2);
    BN_mod_exp(v, md, q2, dsa->q, ctx);
    BN_mod_mul(z1, sig->s, v, dsa->q, ctx);
    BN_sub(tmp, dsa->q, sig->r);
    BN_mod_mul(z2, tmp, v, dsa->p, ctx);
    BN_mod_exp(tmp, dsa->g, z1, dsa->p, ctx);
    BN_mod_exp(tmp2, dsa->pub_key, z2, dsa->p, ctx);
    BN_mod_mul(tmp3, tmp, tmp2, dsa->p, ctx);
    BN_mod(u, tmp3, dsa->q, ctx);
    ok = (BN_cmp(u, sig->r) == 0);

    if (!ok) {
        GOSTerr(GOST_F_GOST_DO_VERIFY, GOST_R_SIGNATURE_MISMATCH);
    }
err:
    if(md) BN_free(md);
    if(ctx) {
        BN_CTX_end(ctx);
        BN_CTX_free(ctx);
    }
    return ok;
}

/*
 * Computes public keys for GOST R 34.10-94 algorithm
 *
 */
int gost94_compute_public(DSA *dsa)
{
    /* Now fill algorithm parameters with correct values */
    BN_CTX *ctx;
    if (!dsa->g) {
        GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC, GOST_R_KEY_IS_NOT_INITALIZED);
        return 0;
    }
    ctx = BN_CTX_new();
    if(!ctx) {
        GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC, ERR_R_MALLOC_FAILURE);
        return 0;
    }

    dsa->pub_key = BN_new();
    if(!dsa->pub_key) {
        GOSTerr(GOST_F_GOST94_COMPUTE_PUBLIC, ERR_R_MALLOC_FAILURE);
        BN_CTX_free(ctx);
        return 0;
    }
    /* Compute public key  y = a^x mod p */
    BN_mod_exp(dsa->pub_key, dsa->g, dsa->priv_key, dsa->p, ctx);
    BN_CTX_free(ctx);
    return 1;
}

/*
 * Fill GOST 94 params, searching them in R3410_paramset array
 * by nid of paramset
 *
 */
int fill_GOST94_params(DSA *dsa, int nid)
{
    R3410_params *params = R3410_paramset;
    while (params->nid != NID_undef && params->nid != nid)
        params++;
    if (params->nid == NID_undef) {
        GOSTerr(GOST_F_FILL_GOST94_PARAMS, GOST_R_UNSUPPORTED_PARAMETER_SET);
        return 0;
    }
#define dump_signature(a,b,c)
    if (dsa->p) {
        BN_free(dsa->p);
    }
    dsa->p = NULL;
    BN_dec2bn(&(dsa->p), params->p);
    if (dsa->q) {
        BN_free(dsa->q);
    }
    dsa->q = NULL;
    BN_dec2bn(&(dsa->q), params->q);
    if (dsa->g) {
        BN_free(dsa->g);
    }
    dsa->g = NULL;
    BN_dec2bn(&(dsa->g), params->a);
    return 1;
}

/*
 *  Generate GOST R 34.10-94 keypair
 *
 *
 */
int gost_sign_keygen(DSA *dsa)
{
    dsa->priv_key = BN_new();
    if(!dsa->priv_key) {
        GOSTerr(GOST_F_GOST_SIGN_KEYGEN, ERR_R_MALLOC_FAILURE);
        return 0;
    }
    BN_rand_range(dsa->priv_key, dsa->q);
    return gost94_compute_public(dsa);
}

/* Unpack signature according to cryptocom rules  */
/*-
DSA_SIG *unpack_cc_signature(const unsigned char *sig,size_t siglen)
        {
        DSA_SIG *s;
        s = DSA_SIG_new();
        if (s == NULL)
                {
                GOSTerr(GOST_F_UNPACK_CC_SIGNATURE,GOST_R_NO_MEMORY);
                return(NULL);
                }
        s->r = getbnfrombuf(sig, siglen/2);
        s->s = getbnfrombuf(sig + siglen/2, siglen/2);
        return s;
        }
*/
/* Unpack signature according to cryptopro rules  */
DSA_SIG *unpack_cp_signature(const unsigned char *sig, size_t siglen)
{
    DSA_SIG *s;

    s = DSA_SIG_new();
    if (s == NULL) {
        GOSTerr(GOST_F_UNPACK_CP_SIGNATURE, GOST_R_NO_MEMORY);
        return NULL;
    }
    s->s = getbnfrombuf(sig, siglen / 2);
    s->r = getbnfrombuf(sig + siglen / 2, siglen / 2);
    return s;
}

/* Convert little-endian byte array into bignum */
BIGNUM *hashsum2bn(const unsigned char *dgst)
{
    unsigned char buf[32];
    int i;
    for (i = 0; i < 32; i++) {
        buf[31 - i] = dgst[i];
    }
    return getbnfrombuf(buf, 32);
}

/* Convert byte buffer to bignum, skipping leading zeros*/
BIGNUM *getbnfrombuf(const unsigned char *buf, size_t len)
{
    while (*buf == 0 && len > 0) {
        buf++;
        len--;
    }
    if (len) {
        return BN_bin2bn(buf, len, NULL);
    } else {
        BIGNUM *b = BN_new();
        BN_zero(b);
        return b;
    }
}

/*
 * Pack bignum into byte buffer of given size, filling all leading bytes by
 * zeros
 */
int store_bignum(BIGNUM *bn, unsigned char *buf, int len)
{
    int bytes = BN_num_bytes(bn);
    if (bytes > len)
        return 0;
    memset(buf, 0, len);
    BN_bn2bin(bn, buf + len - bytes);
    return 1;
}