1 /*
2 * Copyright 2017-2025 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright 2017 Ribose Inc. All Rights Reserved.
4 * Ported from Ribose contributions from Botan.
5 *
6 * Licensed under the Apache License 2.0 (the "License"). You may not use
7 * this file except in compliance with the License. You can obtain a copy
8 * in the file LICENSE in the source distribution or at
9 * https://www.openssl.org/source/license.html
10 */
11
12 #include "internal/deprecated.h"
13
14 #include "crypto/sm2.h"
15 #include "crypto/sm2err.h"
16 #include "crypto/ec.h" /* ossl_ec_group_do_inverse_ord() */
17 #include "internal/numbers.h"
18 #include <openssl/err.h>
19 #include <openssl/evp.h>
20 #include <openssl/bn.h>
21 #include <string.h>
22
ossl_sm2_compute_z_digest(uint8_t * out,const EVP_MD * digest,const uint8_t * id,const size_t id_len,const EC_KEY * key)23 int ossl_sm2_compute_z_digest(uint8_t *out,
24 const EVP_MD *digest,
25 const uint8_t *id,
26 const size_t id_len,
27 const EC_KEY *key)
28 {
29 int rc = 0;
30 const EC_GROUP *group = EC_KEY_get0_group(key);
31 const EC_POINT *pubkey = EC_KEY_get0_public_key(key);
32 BN_CTX *ctx = NULL;
33 EVP_MD_CTX *hash = NULL;
34 BIGNUM *p = NULL;
35 BIGNUM *a = NULL;
36 BIGNUM *b = NULL;
37 BIGNUM *xG = NULL;
38 BIGNUM *yG = NULL;
39 BIGNUM *xA = NULL;
40 BIGNUM *yA = NULL;
41 int p_bytes = 0;
42 uint8_t *buf = NULL;
43 uint16_t entl = 0;
44 uint8_t e_byte = 0;
45
46 /* SM2 Signatures require a public key, check for it */
47 if (pubkey == NULL) {
48 ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
49 goto done;
50 }
51
52 hash = EVP_MD_CTX_new();
53 if (hash == NULL) {
54 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
55 goto done;
56 }
57 ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(key));
58 if (ctx == NULL) {
59 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
60 goto done;
61 }
62
63 p = BN_CTX_get(ctx);
64 a = BN_CTX_get(ctx);
65 b = BN_CTX_get(ctx);
66 xG = BN_CTX_get(ctx);
67 yG = BN_CTX_get(ctx);
68 xA = BN_CTX_get(ctx);
69 yA = BN_CTX_get(ctx);
70
71 if (yA == NULL) {
72 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
73 goto done;
74 }
75
76 if (!EVP_DigestInit(hash, digest)) {
77 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
78 goto done;
79 }
80
81 /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */
82
83 if (id_len >= (UINT16_MAX / 8)) {
84 /* too large */
85 ERR_raise(ERR_LIB_SM2, SM2_R_ID_TOO_LARGE);
86 goto done;
87 }
88
89 entl = (uint16_t)(8 * id_len);
90
91 e_byte = entl >> 8;
92 if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
93 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
94 goto done;
95 }
96 e_byte = entl & 0xFF;
97 if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
98 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
99 goto done;
100 }
101
102 if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) {
103 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
104 goto done;
105 }
106
107 if (!EC_GROUP_get_curve(group, p, a, b, ctx)) {
108 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
109 goto done;
110 }
111
112 p_bytes = BN_num_bytes(p);
113 buf = OPENSSL_zalloc(p_bytes);
114 if (buf == NULL)
115 goto done;
116
117 if (BN_bn2binpad(a, buf, p_bytes) < 0
118 || !EVP_DigestUpdate(hash, buf, p_bytes)
119 || BN_bn2binpad(b, buf, p_bytes) < 0
120 || !EVP_DigestUpdate(hash, buf, p_bytes)
121 || !EC_POINT_get_affine_coordinates(group,
122 EC_GROUP_get0_generator(group),
123 xG, yG, ctx)
124 || BN_bn2binpad(xG, buf, p_bytes) < 0
125 || !EVP_DigestUpdate(hash, buf, p_bytes)
126 || BN_bn2binpad(yG, buf, p_bytes) < 0
127 || !EVP_DigestUpdate(hash, buf, p_bytes)
128 || !EC_POINT_get_affine_coordinates(group,
129 pubkey,
130 xA, yA, ctx)
131 || BN_bn2binpad(xA, buf, p_bytes) < 0
132 || !EVP_DigestUpdate(hash, buf, p_bytes)
133 || BN_bn2binpad(yA, buf, p_bytes) < 0
134 || !EVP_DigestUpdate(hash, buf, p_bytes)
135 || !EVP_DigestFinal(hash, out, NULL)) {
136 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
137 goto done;
138 }
139
140 rc = 1;
141
142 done:
143 OPENSSL_free(buf);
144 BN_CTX_free(ctx);
145 EVP_MD_CTX_free(hash);
146 return rc;
147 }
148
sm2_compute_msg_hash(const EVP_MD * digest,const EC_KEY * key,const uint8_t * id,const size_t id_len,const uint8_t * msg,size_t msg_len)149 static BIGNUM *sm2_compute_msg_hash(const EVP_MD *digest,
150 const EC_KEY *key,
151 const uint8_t *id,
152 const size_t id_len,
153 const uint8_t *msg, size_t msg_len)
154 {
155 EVP_MD_CTX *hash = EVP_MD_CTX_new();
156 const int md_size = EVP_MD_get_size(digest);
157 uint8_t *z = NULL;
158 BIGNUM *e = NULL;
159 EVP_MD *fetched_digest = NULL;
160 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
161 const char *propq = ossl_ec_key_get0_propq(key);
162
163 if (md_size <= 0) {
164 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_DIGEST);
165 goto done;
166 }
167 if (hash == NULL) {
168 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
169 goto done;
170 }
171
172 z = OPENSSL_zalloc(md_size);
173 if (z == NULL)
174 goto done;
175
176 fetched_digest = EVP_MD_fetch(libctx, EVP_MD_get0_name(digest), propq);
177 if (fetched_digest == NULL) {
178 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
179 goto done;
180 }
181
182 if (!ossl_sm2_compute_z_digest(z, fetched_digest, id, id_len, key)) {
183 /* SM2err already called */
184 goto done;
185 }
186
187 if (!EVP_DigestInit(hash, fetched_digest)
188 || !EVP_DigestUpdate(hash, z, md_size)
189 || !EVP_DigestUpdate(hash, msg, msg_len)
190 /* reuse z buffer to hold H(Z || M) */
191 || !EVP_DigestFinal(hash, z, NULL)) {
192 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
193 goto done;
194 }
195
196 e = BN_bin2bn(z, md_size, NULL);
197 if (e == NULL)
198 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
199
200 done:
201 EVP_MD_free(fetched_digest);
202 OPENSSL_free(z);
203 EVP_MD_CTX_free(hash);
204 return e;
205 }
206
sm2_sig_gen(const EC_KEY * key,const BIGNUM * e)207 static ECDSA_SIG *sm2_sig_gen(const EC_KEY *key, const BIGNUM *e)
208 {
209 const BIGNUM *dA = EC_KEY_get0_private_key(key);
210 const EC_GROUP *group = EC_KEY_get0_group(key);
211 const BIGNUM *order = EC_GROUP_get0_order(group);
212 ECDSA_SIG *sig = NULL;
213 EC_POINT *kG = NULL;
214 BN_CTX *ctx = NULL;
215 BIGNUM *k = NULL;
216 BIGNUM *rk = NULL;
217 BIGNUM *r = NULL;
218 BIGNUM *s = NULL;
219 BIGNUM *x1 = NULL;
220 BIGNUM *tmp = NULL;
221 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
222
223 if (dA == NULL) {
224 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_PRIVATE_KEY);
225 goto done;
226 }
227 kG = EC_POINT_new(group);
228 if (kG == NULL) {
229 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
230 goto done;
231 }
232 ctx = BN_CTX_new_ex(libctx);
233 if (ctx == NULL) {
234 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
235 goto done;
236 }
237
238 BN_CTX_start(ctx);
239 k = BN_CTX_get(ctx);
240 rk = BN_CTX_get(ctx);
241 x1 = BN_CTX_get(ctx);
242 tmp = BN_CTX_get(ctx);
243 if (tmp == NULL) {
244 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
245 goto done;
246 }
247
248 /*
249 * These values are returned and so should not be allocated out of the
250 * context
251 */
252 r = BN_new();
253 s = BN_new();
254
255 if (r == NULL || s == NULL) {
256 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
257 goto done;
258 }
259
260 /*
261 * A3: Generate a random number k in [1,n-1] using random number generators;
262 * A4: Compute (x1,y1)=[k]G, and convert the type of data x1 to be integer
263 * as specified in clause 4.2.8 of GM/T 0003.1-2012;
264 * A5: Compute r=(e+x1) mod n. If r=0 or r+k=n, then go to A3;
265 * A6: Compute s=(1/(1+dA)*(k-r*dA)) mod n. If s=0, then go to A3;
266 * A7: Convert the type of data (r,s) to be bit strings according to the details
267 * in clause 4.2.2 of GM/T 0003.1-2012. Then the signature of message M is (r,s).
268 */
269 for (;;) {
270 if (!BN_priv_rand_range_ex(k, order, 0, ctx)) {
271 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
272 goto done;
273 }
274
275 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
276 || !EC_POINT_get_affine_coordinates(group, kG, x1, NULL,
277 ctx)
278 || !BN_mod_add(r, e, x1, order, ctx)) {
279 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
280 goto done;
281 }
282
283 /* try again if r == 0 or r+k == n */
284 if (BN_is_zero(r))
285 continue;
286
287 if (!BN_add(rk, r, k)) {
288 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
289 goto done;
290 }
291
292 if (BN_cmp(rk, order) == 0)
293 continue;
294
295 if (!BN_add(s, dA, BN_value_one())
296 || !ossl_ec_group_do_inverse_ord(group, s, s, ctx)
297 || !BN_mod_mul(tmp, dA, r, order, ctx)
298 || !BN_sub(tmp, k, tmp)
299 || !BN_mod_mul(s, s, tmp, order, ctx)) {
300 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
301 goto done;
302 }
303
304 /* try again if s == 0 */
305 if (BN_is_zero(s))
306 continue;
307
308 sig = ECDSA_SIG_new();
309 if (sig == NULL) {
310 ERR_raise(ERR_LIB_SM2, ERR_R_ECDSA_LIB);
311 goto done;
312 }
313
314 /* takes ownership of r and s */
315 ECDSA_SIG_set0(sig, r, s);
316 break;
317 }
318
319 done:
320 if (sig == NULL) {
321 BN_free(r);
322 BN_free(s);
323 }
324
325 BN_CTX_free(ctx);
326 EC_POINT_free(kG);
327 return sig;
328 }
329
sm2_sig_verify(const EC_KEY * key,const ECDSA_SIG * sig,const BIGNUM * e)330 static int sm2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig,
331 const BIGNUM *e)
332 {
333 int ret = 0;
334 const EC_GROUP *group = EC_KEY_get0_group(key);
335 const BIGNUM *order = EC_GROUP_get0_order(group);
336 BN_CTX *ctx = NULL;
337 EC_POINT *pt = NULL;
338 BIGNUM *t = NULL;
339 BIGNUM *x1 = NULL;
340 const BIGNUM *r = NULL;
341 const BIGNUM *s = NULL;
342 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
343
344 ctx = BN_CTX_new_ex(libctx);
345 if (ctx == NULL) {
346 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
347 goto done;
348 }
349 BN_CTX_start(ctx);
350 t = BN_CTX_get(ctx);
351 x1 = BN_CTX_get(ctx);
352 if (x1 == NULL) {
353 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
354 goto done;
355 }
356
357 pt = EC_POINT_new(group);
358 if (pt == NULL) {
359 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
360 goto done;
361 }
362
363 /*
364 * B1: verify whether r' in [1,n-1], verification failed if not
365 * B2: verify whether s' in [1,n-1], verification failed if not
366 * B3: set M'~=ZA || M'
367 * B4: calculate e'=Hv(M'~)
368 * B5: calculate t = (r' + s') modn, verification failed if t=0
369 * B6: calculate the point (x1', y1')=[s']G + [t]PA
370 * B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed
371 */
372
373 ECDSA_SIG_get0(sig, &r, &s);
374
375 if (BN_cmp(r, BN_value_one()) < 0
376 || BN_cmp(s, BN_value_one()) < 0
377 || BN_cmp(order, r) <= 0
378 || BN_cmp(order, s) <= 0) {
379 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
380 goto done;
381 }
382
383 if (!BN_mod_add(t, r, s, order, ctx)) {
384 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
385 goto done;
386 }
387
388 if (BN_is_zero(t)) {
389 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
390 goto done;
391 }
392
393 if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx)
394 || !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) {
395 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
396 goto done;
397 }
398
399 if (!BN_mod_add(t, e, x1, order, ctx)) {
400 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
401 goto done;
402 }
403
404 if (BN_cmp(r, t) == 0)
405 ret = 1;
406
407 done:
408 BN_CTX_end(ctx);
409 EC_POINT_free(pt);
410 BN_CTX_free(ctx);
411 return ret;
412 }
413
ossl_sm2_do_sign(const EC_KEY * key,const EVP_MD * digest,const uint8_t * id,const size_t id_len,const uint8_t * msg,size_t msg_len)414 ECDSA_SIG *ossl_sm2_do_sign(const EC_KEY *key,
415 const EVP_MD *digest,
416 const uint8_t *id,
417 const size_t id_len,
418 const uint8_t *msg, size_t msg_len)
419 {
420 BIGNUM *e = NULL;
421 ECDSA_SIG *sig = NULL;
422
423 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
424 if (e == NULL) {
425 /* SM2err already called */
426 goto done;
427 }
428
429 sig = sm2_sig_gen(key, e);
430
431 done:
432 BN_free(e);
433 return sig;
434 }
435
ossl_sm2_do_verify(const EC_KEY * key,const EVP_MD * digest,const ECDSA_SIG * sig,const uint8_t * id,const size_t id_len,const uint8_t * msg,size_t msg_len)436 int ossl_sm2_do_verify(const EC_KEY *key,
437 const EVP_MD *digest,
438 const ECDSA_SIG *sig,
439 const uint8_t *id,
440 const size_t id_len,
441 const uint8_t *msg, size_t msg_len)
442 {
443 BIGNUM *e = NULL;
444 int ret = 0;
445
446 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
447 if (e == NULL) {
448 /* SM2err already called */
449 goto done;
450 }
451
452 ret = sm2_sig_verify(key, sig, e);
453
454 done:
455 BN_free(e);
456 return ret;
457 }
458
ossl_sm2_internal_sign(const unsigned char * dgst,int dgstlen,unsigned char * sig,unsigned int * siglen,EC_KEY * eckey)459 int ossl_sm2_internal_sign(const unsigned char *dgst, int dgstlen,
460 unsigned char *sig, unsigned int *siglen,
461 EC_KEY *eckey)
462 {
463 BIGNUM *e = NULL;
464 ECDSA_SIG *s = NULL;
465 int sigleni;
466 int ret = -1;
467
468 if (sig == NULL) {
469 ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
470 goto done;
471 }
472
473 e = BN_bin2bn(dgst, dgstlen, NULL);
474 if (e == NULL) {
475 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
476 goto done;
477 }
478
479 s = sm2_sig_gen(eckey, e);
480 if (s == NULL) {
481 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
482 goto done;
483 }
484
485 sigleni = i2d_ECDSA_SIG(s, &sig);
486 if (sigleni < 0) {
487 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
488 goto done;
489 }
490 *siglen = (unsigned int)sigleni;
491
492 ret = 1;
493
494 done:
495 ECDSA_SIG_free(s);
496 BN_free(e);
497 return ret;
498 }
499
ossl_sm2_internal_verify(const unsigned char * dgst,int dgstlen,const unsigned char * sig,int sig_len,EC_KEY * eckey)500 int ossl_sm2_internal_verify(const unsigned char *dgst, int dgstlen,
501 const unsigned char *sig, int sig_len,
502 EC_KEY *eckey)
503 {
504 ECDSA_SIG *s = NULL;
505 BIGNUM *e = NULL;
506 const unsigned char *p = sig;
507 unsigned char *der = NULL;
508 int derlen = -1;
509 int ret = -1;
510
511 s = ECDSA_SIG_new();
512 if (s == NULL) {
513 ERR_raise(ERR_LIB_SM2, ERR_R_ECDSA_LIB);
514 goto done;
515 }
516 if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) {
517 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
518 goto done;
519 }
520 /* Ensure signature uses DER and doesn't have trailing garbage */
521 derlen = i2d_ECDSA_SIG(s, &der);
522 if (derlen != sig_len || memcmp(sig, der, derlen) != 0) {
523 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
524 goto done;
525 }
526
527 e = BN_bin2bn(dgst, dgstlen, NULL);
528 if (e == NULL) {
529 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
530 goto done;
531 }
532
533 ret = sm2_sig_verify(eckey, s, e);
534
535 done:
536 OPENSSL_free(der);
537 BN_free(e);
538 ECDSA_SIG_free(s);
539 return ret;
540 }
541