1 /*
2 * Copyright 2017-2024 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/err.h>
21 #include <openssl/bn.h>
22 #include <string.h>
23
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)24 int ossl_sm2_compute_z_digest(uint8_t *out,
25 const EVP_MD *digest,
26 const uint8_t *id,
27 const size_t id_len,
28 const EC_KEY *key)
29 {
30 int rc = 0;
31 const EC_GROUP *group = EC_KEY_get0_group(key);
32 const EC_POINT *pubkey = EC_KEY_get0_public_key(key);
33 BN_CTX *ctx = NULL;
34 EVP_MD_CTX *hash = NULL;
35 BIGNUM *p = NULL;
36 BIGNUM *a = NULL;
37 BIGNUM *b = NULL;
38 BIGNUM *xG = NULL;
39 BIGNUM *yG = NULL;
40 BIGNUM *xA = NULL;
41 BIGNUM *yA = NULL;
42 int p_bytes = 0;
43 uint8_t *buf = NULL;
44 uint16_t entl = 0;
45 uint8_t e_byte = 0;
46
47 /* SM2 Signatures require a public key, check for it */
48 if (pubkey == NULL) {
49 ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
50 goto done;
51 }
52
53 hash = EVP_MD_CTX_new();
54 ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(key));
55 if (hash == NULL || ctx == NULL) {
56 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
57 goto done;
58 }
59
60 p = BN_CTX_get(ctx);
61 a = BN_CTX_get(ctx);
62 b = BN_CTX_get(ctx);
63 xG = BN_CTX_get(ctx);
64 yG = BN_CTX_get(ctx);
65 xA = BN_CTX_get(ctx);
66 yA = BN_CTX_get(ctx);
67
68 if (yA == NULL) {
69 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
70 goto done;
71 }
72
73 if (!EVP_DigestInit(hash, digest)) {
74 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
75 goto done;
76 }
77
78 /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */
79
80 if (id_len >= (UINT16_MAX / 8)) {
81 /* too large */
82 ERR_raise(ERR_LIB_SM2, SM2_R_ID_TOO_LARGE);
83 goto done;
84 }
85
86 entl = (uint16_t)(8 * id_len);
87
88 e_byte = entl >> 8;
89 if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
90 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
91 goto done;
92 }
93 e_byte = entl & 0xFF;
94 if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
95 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
96 goto done;
97 }
98
99 if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) {
100 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
101 goto done;
102 }
103
104 if (!EC_GROUP_get_curve(group, p, a, b, ctx)) {
105 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
106 goto done;
107 }
108
109 p_bytes = BN_num_bytes(p);
110 buf = OPENSSL_zalloc(p_bytes);
111 if (buf == NULL) {
112 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
113 goto done;
114 }
115
116 if (BN_bn2binpad(a, buf, p_bytes) < 0
117 || !EVP_DigestUpdate(hash, buf, p_bytes)
118 || BN_bn2binpad(b, buf, p_bytes) < 0
119 || !EVP_DigestUpdate(hash, buf, p_bytes)
120 || !EC_POINT_get_affine_coordinates(group,
121 EC_GROUP_get0_generator(group),
122 xG, yG, ctx)
123 || BN_bn2binpad(xG, buf, p_bytes) < 0
124 || !EVP_DigestUpdate(hash, buf, p_bytes)
125 || BN_bn2binpad(yG, buf, p_bytes) < 0
126 || !EVP_DigestUpdate(hash, buf, p_bytes)
127 || !EC_POINT_get_affine_coordinates(group,
128 pubkey,
129 xA, yA, ctx)
130 || BN_bn2binpad(xA, buf, p_bytes) < 0
131 || !EVP_DigestUpdate(hash, buf, p_bytes)
132 || BN_bn2binpad(yA, buf, p_bytes) < 0
133 || !EVP_DigestUpdate(hash, buf, p_bytes)
134 || !EVP_DigestFinal(hash, out, NULL)) {
135 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
136 goto done;
137 }
138
139 rc = 1;
140
141 done:
142 OPENSSL_free(buf);
143 BN_CTX_free(ctx);
144 EVP_MD_CTX_free(hash);
145 return rc;
146 }
147
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)148 static BIGNUM *sm2_compute_msg_hash(const EVP_MD *digest,
149 const EC_KEY *key,
150 const uint8_t *id,
151 const size_t id_len,
152 const uint8_t *msg, size_t msg_len)
153 {
154 EVP_MD_CTX *hash = EVP_MD_CTX_new();
155 const int md_size = EVP_MD_get_size(digest);
156 uint8_t *z = NULL;
157 BIGNUM *e = NULL;
158 EVP_MD *fetched_digest = NULL;
159 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
160 const char *propq = ossl_ec_key_get0_propq(key);
161
162 if (md_size < 0) {
163 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_DIGEST);
164 goto done;
165 }
166
167 z = OPENSSL_zalloc(md_size);
168 if (hash == NULL || z == NULL) {
169 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
170 goto done;
171 }
172
173 fetched_digest = EVP_MD_fetch(libctx, EVP_MD_get0_name(digest), propq);
174 if (fetched_digest == NULL) {
175 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
176 goto done;
177 }
178
179 if (!ossl_sm2_compute_z_digest(z, fetched_digest, id, id_len, key)) {
180 /* SM2err already called */
181 goto done;
182 }
183
184 if (!EVP_DigestInit(hash, fetched_digest)
185 || !EVP_DigestUpdate(hash, z, md_size)
186 || !EVP_DigestUpdate(hash, msg, msg_len)
187 /* reuse z buffer to hold H(Z || M) */
188 || !EVP_DigestFinal(hash, z, NULL)) {
189 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
190 goto done;
191 }
192
193 e = BN_bin2bn(z, md_size, NULL);
194 if (e == NULL)
195 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
196
197 done:
198 EVP_MD_free(fetched_digest);
199 OPENSSL_free(z);
200 EVP_MD_CTX_free(hash);
201 return e;
202 }
203
sm2_sig_gen(const EC_KEY * key,const BIGNUM * e)204 static ECDSA_SIG *sm2_sig_gen(const EC_KEY *key, const BIGNUM *e)
205 {
206 const BIGNUM *dA = EC_KEY_get0_private_key(key);
207 const EC_GROUP *group = EC_KEY_get0_group(key);
208 const BIGNUM *order = EC_GROUP_get0_order(group);
209 ECDSA_SIG *sig = NULL;
210 EC_POINT *kG = NULL;
211 BN_CTX *ctx = NULL;
212 BIGNUM *k = NULL;
213 BIGNUM *rk = NULL;
214 BIGNUM *r = NULL;
215 BIGNUM *s = NULL;
216 BIGNUM *x1 = NULL;
217 BIGNUM *tmp = NULL;
218 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
219
220 kG = EC_POINT_new(group);
221 ctx = BN_CTX_new_ex(libctx);
222 if (kG == NULL || ctx == NULL) {
223 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
224 goto done;
225 }
226
227 BN_CTX_start(ctx);
228 k = BN_CTX_get(ctx);
229 rk = BN_CTX_get(ctx);
230 x1 = BN_CTX_get(ctx);
231 tmp = BN_CTX_get(ctx);
232 if (tmp == NULL) {
233 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
234 goto done;
235 }
236
237 /*
238 * These values are returned and so should not be allocated out of the
239 * context
240 */
241 r = BN_new();
242 s = BN_new();
243
244 if (r == NULL || s == NULL) {
245 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
246 goto done;
247 }
248
249 /*
250 * A3: Generate a random number k in [1,n-1] using random number generators;
251 * A4: Compute (x1,y1)=[k]G, and convert the type of data x1 to be integer
252 * as specified in clause 4.2.8 of GM/T 0003.1-2012;
253 * A5: Compute r=(e+x1) mod n. If r=0 or r+k=n, then go to A3;
254 * A6: Compute s=(1/(1+dA)*(k-r*dA)) mod n. If s=0, then go to A3;
255 * A7: Convert the type of data (r,s) to be bit strings according to the details
256 * in clause 4.2.2 of GM/T 0003.1-2012. Then the signature of message M is (r,s).
257 */
258 for (;;) {
259 if (!BN_priv_rand_range_ex(k, order, 0, ctx)) {
260 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
261 goto done;
262 }
263
264 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
265 || !EC_POINT_get_affine_coordinates(group, kG, x1, NULL,
266 ctx)
267 || !BN_mod_add(r, e, x1, order, ctx)) {
268 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
269 goto done;
270 }
271
272 /* try again if r == 0 or r+k == n */
273 if (BN_is_zero(r))
274 continue;
275
276 if (!BN_add(rk, r, k)) {
277 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
278 goto done;
279 }
280
281 if (BN_cmp(rk, order) == 0)
282 continue;
283
284 if (!BN_add(s, dA, BN_value_one())
285 || !ossl_ec_group_do_inverse_ord(group, s, s, ctx)
286 || !BN_mod_mul(tmp, dA, r, order, ctx)
287 || !BN_sub(tmp, k, tmp)
288 || !BN_mod_mul(s, s, tmp, order, ctx)) {
289 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
290 goto done;
291 }
292
293 /* try again if s == 0 */
294 if (BN_is_zero(s))
295 continue;
296
297 sig = ECDSA_SIG_new();
298 if (sig == NULL) {
299 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
300 goto done;
301 }
302
303 /* takes ownership of r and s */
304 ECDSA_SIG_set0(sig, r, s);
305 break;
306 }
307
308 done:
309 if (sig == NULL) {
310 BN_free(r);
311 BN_free(s);
312 }
313
314 BN_CTX_free(ctx);
315 EC_POINT_free(kG);
316 return sig;
317 }
318
sm2_sig_verify(const EC_KEY * key,const ECDSA_SIG * sig,const BIGNUM * e)319 static int sm2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig,
320 const BIGNUM *e)
321 {
322 int ret = 0;
323 const EC_GROUP *group = EC_KEY_get0_group(key);
324 const BIGNUM *order = EC_GROUP_get0_order(group);
325 BN_CTX *ctx = NULL;
326 EC_POINT *pt = NULL;
327 BIGNUM *t = NULL;
328 BIGNUM *x1 = NULL;
329 const BIGNUM *r = NULL;
330 const BIGNUM *s = NULL;
331 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
332
333 ctx = BN_CTX_new_ex(libctx);
334 pt = EC_POINT_new(group);
335 if (ctx == NULL || pt == NULL) {
336 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
337 goto done;
338 }
339
340 BN_CTX_start(ctx);
341 t = BN_CTX_get(ctx);
342 x1 = BN_CTX_get(ctx);
343 if (x1 == NULL) {
344 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
345 goto done;
346 }
347
348 /*
349 * B1: verify whether r' in [1,n-1], verification failed if not
350 * B2: verify whether s' in [1,n-1], verification failed if not
351 * B3: set M'~=ZA || M'
352 * B4: calculate e'=Hv(M'~)
353 * B5: calculate t = (r' + s') modn, verification failed if t=0
354 * B6: calculate the point (x1', y1')=[s']G + [t]PA
355 * B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed
356 */
357
358 ECDSA_SIG_get0(sig, &r, &s);
359
360 if (BN_cmp(r, BN_value_one()) < 0
361 || BN_cmp(s, BN_value_one()) < 0
362 || BN_cmp(order, r) <= 0
363 || BN_cmp(order, s) <= 0) {
364 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
365 goto done;
366 }
367
368 if (!BN_mod_add(t, r, s, order, ctx)) {
369 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
370 goto done;
371 }
372
373 if (BN_is_zero(t)) {
374 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
375 goto done;
376 }
377
378 if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx)
379 || !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) {
380 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
381 goto done;
382 }
383
384 if (!BN_mod_add(t, e, x1, order, ctx)) {
385 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
386 goto done;
387 }
388
389 if (BN_cmp(r, t) == 0)
390 ret = 1;
391
392 done:
393 EC_POINT_free(pt);
394 BN_CTX_free(ctx);
395 return ret;
396 }
397
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)398 ECDSA_SIG *ossl_sm2_do_sign(const EC_KEY *key,
399 const EVP_MD *digest,
400 const uint8_t *id,
401 const size_t id_len,
402 const uint8_t *msg, size_t msg_len)
403 {
404 BIGNUM *e = NULL;
405 ECDSA_SIG *sig = NULL;
406
407 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
408 if (e == NULL) {
409 /* SM2err already called */
410 goto done;
411 }
412
413 sig = sm2_sig_gen(key, e);
414
415 done:
416 BN_free(e);
417 return sig;
418 }
419
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)420 int ossl_sm2_do_verify(const EC_KEY *key,
421 const EVP_MD *digest,
422 const ECDSA_SIG *sig,
423 const uint8_t *id,
424 const size_t id_len,
425 const uint8_t *msg, size_t msg_len)
426 {
427 BIGNUM *e = NULL;
428 int ret = 0;
429
430 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
431 if (e == NULL) {
432 /* SM2err already called */
433 goto done;
434 }
435
436 ret = sm2_sig_verify(key, sig, e);
437
438 done:
439 BN_free(e);
440 return ret;
441 }
442
ossl_sm2_internal_sign(const unsigned char * dgst,int dgstlen,unsigned char * sig,unsigned int * siglen,EC_KEY * eckey)443 int ossl_sm2_internal_sign(const unsigned char *dgst, int dgstlen,
444 unsigned char *sig, unsigned int *siglen,
445 EC_KEY *eckey)
446 {
447 BIGNUM *e = NULL;
448 ECDSA_SIG *s = NULL;
449 int sigleni;
450 int ret = -1;
451
452 if (sig == NULL) {
453 ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
454 goto done;
455 }
456
457 e = BN_bin2bn(dgst, dgstlen, NULL);
458 if (e == NULL) {
459 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
460 goto done;
461 }
462
463 s = sm2_sig_gen(eckey, e);
464 if (s == NULL) {
465 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
466 goto done;
467 }
468
469 sigleni = i2d_ECDSA_SIG(s, &sig);
470 if (sigleni < 0) {
471 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
472 goto done;
473 }
474 *siglen = (unsigned int)sigleni;
475
476 ret = 1;
477
478 done:
479 ECDSA_SIG_free(s);
480 BN_free(e);
481 return ret;
482 }
483
ossl_sm2_internal_verify(const unsigned char * dgst,int dgstlen,const unsigned char * sig,int sig_len,EC_KEY * eckey)484 int ossl_sm2_internal_verify(const unsigned char *dgst, int dgstlen,
485 const unsigned char *sig, int sig_len,
486 EC_KEY *eckey)
487 {
488 ECDSA_SIG *s = NULL;
489 BIGNUM *e = NULL;
490 const unsigned char *p = sig;
491 unsigned char *der = NULL;
492 int derlen = -1;
493 int ret = -1;
494
495 s = ECDSA_SIG_new();
496 if (s == NULL) {
497 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
498 goto done;
499 }
500 if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) {
501 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
502 goto done;
503 }
504 /* Ensure signature uses DER and doesn't have trailing garbage */
505 derlen = i2d_ECDSA_SIG(s, &der);
506 if (derlen != sig_len || memcmp(sig, der, derlen) != 0) {
507 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
508 goto done;
509 }
510
511 e = BN_bin2bn(dgst, dgstlen, NULL);
512 if (e == NULL) {
513 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
514 goto done;
515 }
516
517 ret = sm2_sig_verify(eckey, s, e);
518
519 done:
520 OPENSSL_free(der);
521 BN_free(e);
522 ECDSA_SIG_free(s);
523 return ret;
524 }
525