1 /* crypto/ecdsa/ecs_ossl.c */
2 /*
3 * Written by Nils Larsch for the OpenSSL project
4 */
5 /* ====================================================================
6 * Copyright (c) 1998-2004 The OpenSSL Project. All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 *
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in
17 * the documentation and/or other materials provided with the
18 * distribution.
19 *
20 * 3. All advertising materials mentioning features or use of this
21 * software must display the following acknowledgment:
22 * "This product includes software developed by the OpenSSL Project
23 * for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
24 *
25 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
26 * endorse or promote products derived from this software without
27 * prior written permission. For written permission, please contact
28 * openssl-core@OpenSSL.org.
29 *
30 * 5. Products derived from this software may not be called "OpenSSL"
31 * nor may "OpenSSL" appear in their names without prior written
32 * permission of the OpenSSL Project.
33 *
34 * 6. Redistributions of any form whatsoever must retain the following
35 * acknowledgment:
36 * "This product includes software developed by the OpenSSL Project
37 * for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
38 *
39 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
40 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
41 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
42 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
43 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
44 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
45 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
46 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
48 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
49 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
50 * OF THE POSSIBILITY OF SUCH DAMAGE.
51 * ====================================================================
52 *
53 * This product includes cryptographic software written by Eric Young
54 * (eay@cryptsoft.com). This product includes software written by Tim
55 * Hudson (tjh@cryptsoft.com).
56 *
57 */
58
59 #include "ecs_locl.h"
60 #include <openssl/err.h>
61 #include <openssl/obj_mac.h>
62 #include <openssl/bn.h>
63
64 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dlen,
65 const BIGNUM *, const BIGNUM *, EC_KEY *eckey);
66 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
67 BIGNUM **rp);
68 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
69 const ECDSA_SIG *sig, EC_KEY *eckey);
70
71 static ECDSA_METHOD openssl_ecdsa_meth = {
72 "OpenSSL ECDSA method",
73 ecdsa_do_sign,
74 ecdsa_sign_setup,
75 ecdsa_do_verify,
76 #if 0
77 NULL, /* init */
78 NULL, /* finish */
79 #endif
80 0, /* flags */
81 NULL /* app_data */
82 };
83
ECDSA_OpenSSL(void)84 const ECDSA_METHOD *ECDSA_OpenSSL(void)
85 {
86 return &openssl_ecdsa_meth;
87 }
88
ecdsa_sign_setup(EC_KEY * eckey,BN_CTX * ctx_in,BIGNUM ** kinvp,BIGNUM ** rp)89 static int ecdsa_sign_setup(EC_KEY *eckey, BN_CTX *ctx_in, BIGNUM **kinvp,
90 BIGNUM **rp)
91 {
92 BN_CTX *ctx = NULL;
93 BIGNUM *k = NULL, *r = NULL, *order = NULL, *X = NULL;
94 EC_POINT *tmp_point=NULL;
95 const EC_GROUP *group;
96 int ret = 0;
97
98 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL)
99 {
100 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_PASSED_NULL_PARAMETER);
101 return 0;
102 }
103
104 if (ctx_in == NULL)
105 {
106 if ((ctx = BN_CTX_new()) == NULL)
107 {
108 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_MALLOC_FAILURE);
109 return 0;
110 }
111 }
112 else
113 ctx = ctx_in;
114
115 k = BN_new(); /* this value is later returned in *kinvp */
116 r = BN_new(); /* this value is later returned in *rp */
117 order = BN_new();
118 X = BN_new();
119 if (!k || !r || !order || !X)
120 {
121 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_MALLOC_FAILURE);
122 goto err;
123 }
124 if ((tmp_point = EC_POINT_new(group)) == NULL)
125 {
126 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
127 goto err;
128 }
129 if (!EC_GROUP_get_order(group, order, ctx))
130 {
131 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
132 goto err;
133 }
134
135 do
136 {
137 /* get random k */
138 do
139 if (!BN_rand_range(k, order))
140 {
141 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,
142 ECDSA_R_RANDOM_NUMBER_GENERATION_FAILED);
143 goto err;
144 }
145 while (BN_is_zero(k));
146
147 /* compute r the x-coordinate of generator * k */
148 if (!EC_POINT_mul(group, tmp_point, k, NULL, NULL, ctx))
149 {
150 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_EC_LIB);
151 goto err;
152 }
153 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
154 {
155 if (!EC_POINT_get_affine_coordinates_GFp(group,
156 tmp_point, X, NULL, ctx))
157 {
158 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
159 goto err;
160 }
161 }
162 else /* NID_X9_62_characteristic_two_field */
163 {
164 if (!EC_POINT_get_affine_coordinates_GF2m(group,
165 tmp_point, X, NULL, ctx))
166 {
167 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP,ERR_R_EC_LIB);
168 goto err;
169 }
170 }
171 if (!BN_nnmod(r, X, order, ctx))
172 {
173 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
174 goto err;
175 }
176 }
177 while (BN_is_zero(r));
178
179 /* compute the inverse of k */
180 if (!BN_mod_inverse(k, k, order, ctx))
181 {
182 ECDSAerr(ECDSA_F_ECDSA_SIGN_SETUP, ERR_R_BN_LIB);
183 goto err;
184 }
185 /* clear old values if necessary */
186 if (*rp != NULL)
187 BN_clear_free(*rp);
188 if (*kinvp != NULL)
189 BN_clear_free(*kinvp);
190 /* save the pre-computed values */
191 *rp = r;
192 *kinvp = k;
193 ret = 1;
194 err:
195 if (!ret)
196 {
197 if (k != NULL) BN_clear_free(k);
198 if (r != NULL) BN_clear_free(r);
199 }
200 if (ctx_in == NULL)
201 BN_CTX_free(ctx);
202 if (order != NULL)
203 BN_free(order);
204 if (tmp_point != NULL)
205 EC_POINT_free(tmp_point);
206 if (X)
207 BN_clear_free(X);
208 return(ret);
209 }
210
211
ecdsa_do_sign(const unsigned char * dgst,int dgst_len,const BIGNUM * in_kinv,const BIGNUM * in_r,EC_KEY * eckey)212 static ECDSA_SIG *ecdsa_do_sign(const unsigned char *dgst, int dgst_len,
213 const BIGNUM *in_kinv, const BIGNUM *in_r, EC_KEY *eckey)
214 {
215 int ok = 0;
216 BIGNUM *kinv=NULL, *s, *m=NULL,*tmp=NULL,*order=NULL;
217 const BIGNUM *ckinv;
218 BN_CTX *ctx = NULL;
219 const EC_GROUP *group;
220 ECDSA_SIG *ret;
221 ECDSA_DATA *ecdsa;
222 const BIGNUM *priv_key;
223
224 ecdsa = ecdsa_check(eckey);
225 group = EC_KEY_get0_group(eckey);
226 priv_key = EC_KEY_get0_private_key(eckey);
227
228 if (group == NULL || priv_key == NULL || ecdsa == NULL)
229 {
230 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_PASSED_NULL_PARAMETER);
231 return NULL;
232 }
233
234 ret = ECDSA_SIG_new();
235 if (!ret)
236 {
237 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
238 return NULL;
239 }
240 s = ret->s;
241
242 if ((ctx = BN_CTX_new()) == NULL || (order = BN_new()) == NULL ||
243 (tmp = BN_new()) == NULL || (m = BN_new()) == NULL)
244 {
245 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
246 goto err;
247 }
248
249 if (!EC_GROUP_get_order(group, order, ctx))
250 {
251 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_EC_LIB);
252 goto err;
253 }
254 if (dgst_len > BN_num_bytes(order))
255 {
256 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,
257 ECDSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);
258 goto err;
259 }
260
261 if (!BN_bin2bn(dgst, dgst_len, m))
262 {
263 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
264 goto err;
265 }
266 do
267 {
268 if (in_kinv == NULL || in_r == NULL)
269 {
270 if (!ECDSA_sign_setup(eckey, ctx, &kinv, &ret->r))
271 {
272 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN,ERR_R_ECDSA_LIB);
273 goto err;
274 }
275 ckinv = kinv;
276 }
277 else
278 {
279 ckinv = in_kinv;
280 if (BN_copy(ret->r, in_r) == NULL)
281 {
282 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_MALLOC_FAILURE);
283 goto err;
284 }
285 }
286
287 if (!BN_mod_mul(tmp, priv_key, ret->r, order, ctx))
288 {
289 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
290 goto err;
291 }
292 if (!BN_mod_add_quick(s, tmp, m, order))
293 {
294 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
295 goto err;
296 }
297 if (!BN_mod_mul(s, s, ckinv, order, ctx))
298 {
299 ECDSAerr(ECDSA_F_ECDSA_DO_SIGN, ERR_R_BN_LIB);
300 goto err;
301 }
302 }
303 while (BN_is_zero(s));
304
305 ok = 1;
306 err:
307 if (!ok)
308 {
309 ECDSA_SIG_free(ret);
310 ret = NULL;
311 }
312 if (ctx)
313 BN_CTX_free(ctx);
314 if (m)
315 BN_clear_free(m);
316 if (tmp)
317 BN_clear_free(tmp);
318 if (order)
319 BN_free(order);
320 if (kinv)
321 BN_clear_free(kinv);
322 return ret;
323 }
324
ecdsa_do_verify(const unsigned char * dgst,int dgst_len,const ECDSA_SIG * sig,EC_KEY * eckey)325 static int ecdsa_do_verify(const unsigned char *dgst, int dgst_len,
326 const ECDSA_SIG *sig, EC_KEY *eckey)
327 {
328 int ret = -1;
329 BN_CTX *ctx;
330 BIGNUM *order, *u1, *u2, *m, *X;
331 EC_POINT *point = NULL;
332 const EC_GROUP *group;
333 const EC_POINT *pub_key;
334
335 /* check input values */
336 if (eckey == NULL || (group = EC_KEY_get0_group(eckey)) == NULL ||
337 (pub_key = EC_KEY_get0_public_key(eckey)) == NULL || sig == NULL)
338 {
339 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_MISSING_PARAMETERS);
340 return -1;
341 }
342
343 ctx = BN_CTX_new();
344 if (!ctx)
345 {
346 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
347 return -1;
348 }
349 BN_CTX_start(ctx);
350 order = BN_CTX_get(ctx);
351 u1 = BN_CTX_get(ctx);
352 u2 = BN_CTX_get(ctx);
353 m = BN_CTX_get(ctx);
354 X = BN_CTX_get(ctx);
355 if (!X)
356 {
357 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
358 goto err;
359 }
360
361 if (!EC_GROUP_get_order(group, order, ctx))
362 {
363 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
364 goto err;
365 }
366
367 if (BN_is_zero(sig->r) || BN_is_negative(sig->r) ||
368 BN_ucmp(sig->r, order) >= 0 || BN_is_zero(sig->s) ||
369 BN_is_negative(sig->s) || BN_ucmp(sig->s, order) >= 0)
370 {
371 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ECDSA_R_BAD_SIGNATURE);
372 ret = 0; /* signature is invalid */
373 goto err;
374 }
375 /* calculate tmp1 = inv(S) mod order */
376 if (!BN_mod_inverse(u2, sig->s, order, ctx))
377 {
378 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
379 goto err;
380 }
381 /* digest -> m */
382 if (!BN_bin2bn(dgst, dgst_len, m))
383 {
384 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
385 goto err;
386 }
387 /* u1 = m * tmp mod order */
388 if (!BN_mod_mul(u1, m, u2, order, ctx))
389 {
390 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
391 goto err;
392 }
393 /* u2 = r * w mod q */
394 if (!BN_mod_mul(u2, sig->r, u2, order, ctx))
395 {
396 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
397 goto err;
398 }
399
400 if ((point = EC_POINT_new(group)) == NULL)
401 {
402 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_MALLOC_FAILURE);
403 goto err;
404 }
405 if (!EC_POINT_mul(group, point, u1, pub_key, u2, ctx))
406 {
407 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
408 goto err;
409 }
410 if (EC_METHOD_get_field_type(EC_GROUP_method_of(group)) == NID_X9_62_prime_field)
411 {
412 if (!EC_POINT_get_affine_coordinates_GFp(group,
413 point, X, NULL, ctx))
414 {
415 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
416 goto err;
417 }
418 }
419 else /* NID_X9_62_characteristic_two_field */
420 {
421 if (!EC_POINT_get_affine_coordinates_GF2m(group,
422 point, X, NULL, ctx))
423 {
424 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_EC_LIB);
425 goto err;
426 }
427 }
428
429 if (!BN_nnmod(u1, X, order, ctx))
430 {
431 ECDSAerr(ECDSA_F_ECDSA_DO_VERIFY, ERR_R_BN_LIB);
432 goto err;
433 }
434 /* if the signature is correct u1 is equal to sig->r */
435 ret = (BN_ucmp(u1, sig->r) == 0);
436 err:
437 BN_CTX_end(ctx);
438 BN_CTX_free(ctx);
439 if (point)
440 EC_POINT_free(point);
441 return ret;
442 }
443