gost2001.c revision 280304 
1/**********************************************************************
2 *                          gost2001.c                                *
3 *             Copyright (c) 2005-2006 Cryptocom LTD                  *
4 *         This file is distributed under the same license as OpenSSL *
5 *                                                                    *
6 *          Implementation of GOST R 34.10-2001                                   *
7 *          Requires OpenSSL 0.9.9 for compilation                    *
8 **********************************************************************/
9#include "gost_lcl.h"
10#include "gost_params.h"
11#include <string.h>
12#include <openssl/rand.h>
13#include <openssl/ecdsa.h>
14#include <openssl/err.h>
15#include "e_gost_err.h"
16#ifdef DEBUG_SIGN
17extern
18void dump_signature(const char *message, const unsigned char *buffer,
19                    size_t len);
20void dump_dsa_sig(const char *message, DSA_SIG *sig);
21#else
22
23# define dump_signature(a,b,c)
24# define dump_dsa_sig(a,b)
25#endif
26
27/*
28 * Fills EC_KEY structure hidden in the app_data field of DSA structure
29 * with parameter information, extracted from parameter array in
30 * params.c file.
31 *
32 * Also fils DSA->q field with copy of EC_GROUP order field to make
33 * DSA_size function work
34 */
35int fill_GOST2001_params(EC_KEY *eckey, int nid)
36{
37    R3410_2001_params *params = R3410_2001_paramset;
38    EC_GROUP *grp = NULL;
39    BIGNUM *p = NULL, *q = NULL, *a = NULL, *b = NULL, *x = NULL, *y = NULL;
40    EC_POINT *P = NULL;
41    BN_CTX *ctx = BN_CTX_new();
42    int ok = 0;
43
44    BN_CTX_start(ctx);
45    p = BN_CTX_get(ctx);
46    a = BN_CTX_get(ctx);
47    b = BN_CTX_get(ctx);
48    x = BN_CTX_get(ctx);
49    y = BN_CTX_get(ctx);
50    q = BN_CTX_get(ctx);
51    while (params->nid != NID_undef && params->nid != nid)
52        params++;
53    if (params->nid == NID_undef) {
54        GOSTerr(GOST_F_FILL_GOST2001_PARAMS,
55                GOST_R_UNSUPPORTED_PARAMETER_SET);
56        goto err;
57    }
58    BN_hex2bn(&p, params->p);
59    BN_hex2bn(&a, params->a);
60    BN_hex2bn(&b, params->b);
61
62    grp = EC_GROUP_new_curve_GFp(p, a, b, ctx);
63
64    P = EC_POINT_new(grp);
65
66    BN_hex2bn(&x, params->x);
67    BN_hex2bn(&y, params->y);
68    EC_POINT_set_affine_coordinates_GFp(grp, P, x, y, ctx);
69    BN_hex2bn(&q, params->q);
70#ifdef DEBUG_KEYS
71    fprintf(stderr, "Set params index %d oid %s\nq=",
72            (params - R3410_2001_paramset), OBJ_nid2sn(params->nid));
73    BN_print_fp(stderr, q);
74    fprintf(stderr, "\n");
75#endif
76
77    EC_GROUP_set_generator(grp, P, q, NULL);
78    EC_GROUP_set_curve_name(grp, params->nid);
79
80    EC_KEY_set_group(eckey, grp);
81    ok = 1;
82 err:
83    EC_POINT_free(P);
84    EC_GROUP_free(grp);
85    BN_CTX_end(ctx);
86    BN_CTX_free(ctx);
87    return ok;
88}
89
90/*
91 * Computes gost2001 signature as DSA_SIG structure
92 *
93 *
94 */
95DSA_SIG *gost2001_do_sign(const unsigned char *dgst, int dlen, EC_KEY *eckey)
96{
97    DSA_SIG *newsig = NULL;
98    BIGNUM *md = hashsum2bn(dgst);
99    BIGNUM *order = NULL;
100    const EC_GROUP *group;
101    const BIGNUM *priv_key;
102    BIGNUM *r = NULL, *s = NULL, *X = NULL, *tmp = NULL, *tmp2 = NULL, *k =
103        NULL, *e = NULL;
104    EC_POINT *C = NULL;
105    BN_CTX *ctx = BN_CTX_new();
106    BN_CTX_start(ctx);
107    OPENSSL_assert(dlen == 32);
108    newsig = DSA_SIG_new();
109    if (!newsig) {
110        GOSTerr(GOST_F_GOST2001_DO_SIGN, GOST_R_NO_MEMORY);
111        goto err;
112    }
113    group = EC_KEY_get0_group(eckey);
114    order = BN_CTX_get(ctx);
115    EC_GROUP_get_order(group, order, ctx);
116    priv_key = EC_KEY_get0_private_key(eckey);
117    e = BN_CTX_get(ctx);
118    BN_mod(e, md, order, ctx);
119#ifdef DEBUG_SIGN
120    fprintf(stderr, "digest as bignum=");
121    BN_print_fp(stderr, md);
122    fprintf(stderr, "\ndigest mod q=");
123    BN_print_fp(stderr, e);
124    fprintf(stderr, "\n");
125#endif
126    if (BN_is_zero(e)) {
127        BN_one(e);
128    }
129    k = BN_CTX_get(ctx);
130    C = EC_POINT_new(group);
131    do {
132        do {
133            if (!BN_rand_range(k, order)) {
134                GOSTerr(GOST_F_GOST2001_DO_SIGN,
135                        GOST_R_RANDOM_NUMBER_GENERATOR_FAILED);
136                DSA_SIG_free(newsig);
137                newsig = NULL;
138                goto err;
139            }
140            if (!EC_POINT_mul(group, C, k, NULL, NULL, ctx)) {
141                GOSTerr(GOST_F_GOST2001_DO_SIGN, ERR_R_EC_LIB);
142                DSA_SIG_free(newsig);
143                newsig = NULL;
144                goto err;
145            }
146            if (!X)
147                X = BN_CTX_get(ctx);
148            if (!EC_POINT_get_affine_coordinates_GFp(group, C, X, NULL, ctx)) {
149                GOSTerr(GOST_F_GOST2001_DO_SIGN, ERR_R_EC_LIB);
150                DSA_SIG_free(newsig);
151                newsig = NULL;
152                goto err;
153            }
154            if (!r)
155                r = BN_CTX_get(ctx);
156            BN_nnmod(r, X, order, ctx);
157        }
158        while (BN_is_zero(r));
159        /* s =  (r*priv_key+k*e) mod order */
160        if (!tmp)
161            tmp = BN_CTX_get(ctx);
162        BN_mod_mul(tmp, priv_key, r, order, ctx);
163        if (!tmp2)
164            tmp2 = BN_CTX_get(ctx);
165        BN_mod_mul(tmp2, k, e, order, ctx);
166        if (!s)
167            s = BN_CTX_get(ctx);
168        BN_mod_add(s, tmp, tmp2, order, ctx);
169    }
170    while (BN_is_zero(s));
171
172    newsig->s = BN_dup(s);
173    newsig->r = BN_dup(r);
174 err:
175    BN_CTX_end(ctx);
176    BN_CTX_free(ctx);
177    EC_POINT_free(C);
178    BN_free(md);
179    return newsig;
180}
181
182/*
183 * Verifies gost 2001 signature
184 *
185 */
186int gost2001_do_verify(const unsigned char *dgst, int dgst_len,
187                       DSA_SIG *sig, EC_KEY *ec)
188{
189    BN_CTX *ctx = BN_CTX_new();
190    const EC_GROUP *group = EC_KEY_get0_group(ec);
191    BIGNUM *order;
192    BIGNUM *md = NULL, *e = NULL, *R = NULL, *v = NULL, *z1 = NULL, *z2 =
193        NULL;
194    BIGNUM *X = NULL, *tmp = NULL;
195    EC_POINT *C = NULL;
196    const EC_POINT *pub_key = NULL;
197    int ok = 0;
198
199    BN_CTX_start(ctx);
200    order = BN_CTX_get(ctx);
201    e = BN_CTX_get(ctx);
202    z1 = BN_CTX_get(ctx);
203    z2 = BN_CTX_get(ctx);
204    tmp = BN_CTX_get(ctx);
205    X = BN_CTX_get(ctx);
206    R = BN_CTX_get(ctx);
207    v = BN_CTX_get(ctx);
208
209    EC_GROUP_get_order(group, order, ctx);
210    pub_key = EC_KEY_get0_public_key(ec);
211    if (BN_is_zero(sig->s) || BN_is_zero(sig->r) ||
212        (BN_cmp(sig->s, order) >= 1) || (BN_cmp(sig->r, order) >= 1)) {
213        GOSTerr(GOST_F_GOST2001_DO_VERIFY,
214                GOST_R_SIGNATURE_PARTS_GREATER_THAN_Q);
215        goto err;
216
217    }
218    md = hashsum2bn(dgst);
219
220    BN_mod(e, md, order, ctx);
221#ifdef DEBUG_SIGN
222    fprintf(stderr, "digest as bignum: ");
223    BN_print_fp(stderr, md);
224    fprintf(stderr, "\ndigest mod q: ");
225    BN_print_fp(stderr, e);
226#endif
227    if (BN_is_zero(e))
228        BN_one(e);
229    v = BN_mod_inverse(v, e, order, ctx);
230    BN_mod_mul(z1, sig->s, v, order, ctx);
231    BN_sub(tmp, order, sig->r);
232    BN_mod_mul(z2, tmp, v, order, ctx);
233#ifdef DEBUG_SIGN
234    fprintf(stderr, "\nInverted digest value: ");
235    BN_print_fp(stderr, v);
236    fprintf(stderr, "\nz1: ");
237    BN_print_fp(stderr, z1);
238    fprintf(stderr, "\nz2: ");
239    BN_print_fp(stderr, z2);
240#endif
241    C = EC_POINT_new(group);
242    if (!EC_POINT_mul(group, C, z1, pub_key, z2, ctx)) {
243        GOSTerr(GOST_F_GOST2001_DO_VERIFY, ERR_R_EC_LIB);
244        goto err;
245    }
246    if (!EC_POINT_get_affine_coordinates_GFp(group, C, X, NULL, ctx)) {
247        GOSTerr(GOST_F_GOST2001_DO_VERIFY, ERR_R_EC_LIB);
248        goto err;
249    }
250    BN_mod(R, X, order, ctx);
251#ifdef DEBUG_SIGN
252    fprintf(stderr, "\nX=");
253    BN_print_fp(stderr, X);
254    fprintf(stderr, "\nX mod q=");
255    BN_print_fp(stderr, R);
256    fprintf(stderr, "\n");
257#endif
258    if (BN_cmp(R, sig->r) != 0) {
259        GOSTerr(GOST_F_GOST2001_DO_VERIFY, GOST_R_SIGNATURE_MISMATCH);
260    } else {
261        ok = 1;
262    }
263 err:
264    EC_POINT_free(C);
265    BN_CTX_end(ctx);
266    BN_CTX_free(ctx);
267    BN_free(md);
268    return ok;
269}
270
271/*
272 * Computes GOST R 34.10-2001 public key
273 *
274 *
275 */
276int gost2001_compute_public(EC_KEY *ec)
277{
278    const EC_GROUP *group = EC_KEY_get0_group(ec);
279    EC_POINT *pub_key = NULL;
280    const BIGNUM *priv_key = NULL;
281    BN_CTX *ctx = NULL;
282    int ok = 0;
283
284    if (!group) {
285        GOSTerr(GOST_F_GOST2001_COMPUTE_PUBLIC,
286                GOST_R_KEY_IS_NOT_INITIALIZED);
287        return 0;
288    }
289    ctx = BN_CTX_new();
290    BN_CTX_start(ctx);
291    if (!(priv_key = EC_KEY_get0_private_key(ec))) {
292        GOSTerr(GOST_F_GOST2001_COMPUTE_PUBLIC, ERR_R_EC_LIB);
293        goto err;
294    }
295
296    pub_key = EC_POINT_new(group);
297    if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, ctx)) {
298        GOSTerr(GOST_F_GOST2001_COMPUTE_PUBLIC, ERR_R_EC_LIB);
299        goto err;
300    }
301    if (!EC_KEY_set_public_key(ec, pub_key)) {
302        GOSTerr(GOST_F_GOST2001_COMPUTE_PUBLIC, ERR_R_EC_LIB);
303        goto err;
304    }
305    ok = 256;
306 err:
307    BN_CTX_end(ctx);
308    EC_POINT_free(pub_key);
309    BN_CTX_free(ctx);
310    return ok;
311}
312
313/*
314 *
315 * Generates GOST R 34.10-2001 keypair
316 *
317 *
318 */
319int gost2001_keygen(EC_KEY *ec)
320{
321    BIGNUM *order = BN_new(), *d = BN_new();
322    const EC_GROUP *group = EC_KEY_get0_group(ec);
323    EC_GROUP_get_order(group, order, NULL);
324
325    do {
326        if (!BN_rand_range(d, order)) {
327            GOSTerr(GOST_F_GOST2001_KEYGEN,
328                    GOST_R_RANDOM_NUMBER_GENERATOR_FAILED);
329            BN_free(d);
330            BN_free(order);
331            return 0;
332        }
333    }
334    while (BN_is_zero(d));
335    EC_KEY_set_private_key(ec, d);
336    BN_free(d);
337    BN_free(order);
338    return gost2001_compute_public(ec);
339}
340