1 /*
2 * Copyright 2017-2023 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 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 hash = EVP_MD_CTX_new();
47 ctx = BN_CTX_new_ex(ossl_ec_key_get_libctx(key));
48 if (hash == NULL || ctx == NULL) {
49 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
50 goto done;
51 }
52
53 p = BN_CTX_get(ctx);
54 a = BN_CTX_get(ctx);
55 b = BN_CTX_get(ctx);
56 xG = BN_CTX_get(ctx);
57 yG = BN_CTX_get(ctx);
58 xA = BN_CTX_get(ctx);
59 yA = BN_CTX_get(ctx);
60
61 if (yA == NULL) {
62 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
63 goto done;
64 }
65
66 if (!EVP_DigestInit(hash, digest)) {
67 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
68 goto done;
69 }
70
71 /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */
72
73 if (id_len >= (UINT16_MAX / 8)) {
74 /* too large */
75 ERR_raise(ERR_LIB_SM2, SM2_R_ID_TOO_LARGE);
76 goto done;
77 }
78
79 entl = (uint16_t)(8 * id_len);
80
81 e_byte = entl >> 8;
82 if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
83 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
84 goto done;
85 }
86 e_byte = entl & 0xFF;
87 if (!EVP_DigestUpdate(hash, &e_byte, 1)) {
88 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
89 goto done;
90 }
91
92 if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) {
93 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
94 goto done;
95 }
96
97 if (!EC_GROUP_get_curve(group, p, a, b, ctx)) {
98 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
99 goto done;
100 }
101
102 p_bytes = BN_num_bytes(p);
103 buf = OPENSSL_zalloc(p_bytes);
104 if (buf == NULL) {
105 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
106 goto done;
107 }
108
109 if (BN_bn2binpad(a, buf, p_bytes) < 0
110 || !EVP_DigestUpdate(hash, buf, p_bytes)
111 || BN_bn2binpad(b, buf, p_bytes) < 0
112 || !EVP_DigestUpdate(hash, buf, p_bytes)
113 || !EC_POINT_get_affine_coordinates(group,
114 EC_GROUP_get0_generator(group),
115 xG, yG, ctx)
116 || BN_bn2binpad(xG, buf, p_bytes) < 0
117 || !EVP_DigestUpdate(hash, buf, p_bytes)
118 || BN_bn2binpad(yG, buf, p_bytes) < 0
119 || !EVP_DigestUpdate(hash, buf, p_bytes)
120 || !EC_POINT_get_affine_coordinates(group,
121 EC_KEY_get0_public_key(key),
122 xA, yA, ctx)
123 || BN_bn2binpad(xA, buf, p_bytes) < 0
124 || !EVP_DigestUpdate(hash, buf, p_bytes)
125 || BN_bn2binpad(yA, buf, p_bytes) < 0
126 || !EVP_DigestUpdate(hash, buf, p_bytes)
127 || !EVP_DigestFinal(hash, out, NULL)) {
128 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
129 goto done;
130 }
131
132 rc = 1;
133
134 done:
135 OPENSSL_free(buf);
136 BN_CTX_free(ctx);
137 EVP_MD_CTX_free(hash);
138 return rc;
139 }
140
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)141 static BIGNUM *sm2_compute_msg_hash(const EVP_MD *digest,
142 const EC_KEY *key,
143 const uint8_t *id,
144 const size_t id_len,
145 const uint8_t *msg, size_t msg_len)
146 {
147 EVP_MD_CTX *hash = EVP_MD_CTX_new();
148 const int md_size = EVP_MD_get_size(digest);
149 uint8_t *z = NULL;
150 BIGNUM *e = NULL;
151 EVP_MD *fetched_digest = NULL;
152 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
153 const char *propq = ossl_ec_key_get0_propq(key);
154
155 if (md_size < 0) {
156 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_DIGEST);
157 goto done;
158 }
159
160 z = OPENSSL_zalloc(md_size);
161 if (hash == NULL || z == NULL) {
162 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
163 goto done;
164 }
165
166 fetched_digest = EVP_MD_fetch(libctx, EVP_MD_get0_name(digest), propq);
167 if (fetched_digest == NULL) {
168 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
169 goto done;
170 }
171
172 if (!ossl_sm2_compute_z_digest(z, fetched_digest, id, id_len, key)) {
173 /* SM2err already called */
174 goto done;
175 }
176
177 if (!EVP_DigestInit(hash, fetched_digest)
178 || !EVP_DigestUpdate(hash, z, md_size)
179 || !EVP_DigestUpdate(hash, msg, msg_len)
180 /* reuse z buffer to hold H(Z || M) */
181 || !EVP_DigestFinal(hash, z, NULL)) {
182 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
183 goto done;
184 }
185
186 e = BN_bin2bn(z, md_size, NULL);
187 if (e == NULL)
188 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
189
190 done:
191 EVP_MD_free(fetched_digest);
192 OPENSSL_free(z);
193 EVP_MD_CTX_free(hash);
194 return e;
195 }
196
sm2_sig_gen(const EC_KEY * key,const BIGNUM * e)197 static ECDSA_SIG *sm2_sig_gen(const EC_KEY *key, const BIGNUM *e)
198 {
199 const BIGNUM *dA = EC_KEY_get0_private_key(key);
200 const EC_GROUP *group = EC_KEY_get0_group(key);
201 const BIGNUM *order = EC_GROUP_get0_order(group);
202 ECDSA_SIG *sig = NULL;
203 EC_POINT *kG = NULL;
204 BN_CTX *ctx = NULL;
205 BIGNUM *k = NULL;
206 BIGNUM *rk = NULL;
207 BIGNUM *r = NULL;
208 BIGNUM *s = NULL;
209 BIGNUM *x1 = NULL;
210 BIGNUM *tmp = NULL;
211 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
212
213 if (dA == NULL) {
214 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_PRIVATE_KEY);
215 goto done;
216 }
217 kG = EC_POINT_new(group);
218 ctx = BN_CTX_new_ex(libctx);
219 if (kG == NULL || ctx == NULL) {
220 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
221 goto done;
222 }
223
224 BN_CTX_start(ctx);
225 k = BN_CTX_get(ctx);
226 rk = BN_CTX_get(ctx);
227 x1 = BN_CTX_get(ctx);
228 tmp = BN_CTX_get(ctx);
229 if (tmp == NULL) {
230 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
231 goto done;
232 }
233
234 /*
235 * These values are returned and so should not be allocated out of the
236 * context
237 */
238 r = BN_new();
239 s = BN_new();
240
241 if (r == NULL || s == NULL) {
242 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
243 goto done;
244 }
245
246 /*
247 * A3: Generate a random number k in [1,n-1] using random number generators;
248 * A4: Compute (x1,y1)=[k]G, and convert the type of data x1 to be integer
249 * as specified in clause 4.2.8 of GM/T 0003.1-2012;
250 * A5: Compute r=(e+x1) mod n. If r=0 or r+k=n, then go to A3;
251 * A6: Compute s=(1/(1+dA)*(k-r*dA)) mod n. If s=0, then go to A3;
252 * A7: Convert the type of data (r,s) to be bit strings according to the details
253 * in clause 4.2.2 of GM/T 0003.1-2012. Then the signature of message M is (r,s).
254 */
255 for (;;) {
256 if (!BN_priv_rand_range_ex(k, order, 0, ctx)) {
257 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
258 goto done;
259 }
260
261 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
262 || !EC_POINT_get_affine_coordinates(group, kG, x1, NULL,
263 ctx)
264 || !BN_mod_add(r, e, x1, order, ctx)) {
265 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
266 goto done;
267 }
268
269 /* try again if r == 0 or r+k == n */
270 if (BN_is_zero(r))
271 continue;
272
273 if (!BN_add(rk, r, k)) {
274 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
275 goto done;
276 }
277
278 if (BN_cmp(rk, order) == 0)
279 continue;
280
281 if (!BN_add(s, dA, BN_value_one())
282 || !ossl_ec_group_do_inverse_ord(group, s, s, ctx)
283 || !BN_mod_mul(tmp, dA, r, order, ctx)
284 || !BN_sub(tmp, k, tmp)
285 || !BN_mod_mul(s, s, tmp, order, ctx)) {
286 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
287 goto done;
288 }
289
290 /* try again if s == 0 */
291 if (BN_is_zero(s))
292 continue;
293
294 sig = ECDSA_SIG_new();
295 if (sig == NULL) {
296 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
297 goto done;
298 }
299
300 /* takes ownership of r and s */
301 ECDSA_SIG_set0(sig, r, s);
302 break;
303 }
304
305 done:
306 if (sig == NULL) {
307 BN_free(r);
308 BN_free(s);
309 }
310
311 BN_CTX_free(ctx);
312 EC_POINT_free(kG);
313 return sig;
314 }
315
sm2_sig_verify(const EC_KEY * key,const ECDSA_SIG * sig,const BIGNUM * e)316 static int sm2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig,
317 const BIGNUM *e)
318 {
319 int ret = 0;
320 const EC_GROUP *group = EC_KEY_get0_group(key);
321 const BIGNUM *order = EC_GROUP_get0_order(group);
322 BN_CTX *ctx = NULL;
323 EC_POINT *pt = NULL;
324 BIGNUM *t = NULL;
325 BIGNUM *x1 = NULL;
326 const BIGNUM *r = NULL;
327 const BIGNUM *s = NULL;
328 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
329
330 ctx = BN_CTX_new_ex(libctx);
331 pt = EC_POINT_new(group);
332 if (ctx == NULL || pt == NULL) {
333 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
334 goto done;
335 }
336
337 BN_CTX_start(ctx);
338 t = BN_CTX_get(ctx);
339 x1 = BN_CTX_get(ctx);
340 if (x1 == NULL) {
341 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
342 goto done;
343 }
344
345 /*
346 * B1: verify whether r' in [1,n-1], verification failed if not
347 * B2: verify whether s' in [1,n-1], verification failed if not
348 * B3: set M'~=ZA || M'
349 * B4: calculate e'=Hv(M'~)
350 * B5: calculate t = (r' + s') modn, verification failed if t=0
351 * B6: calculate the point (x1', y1')=[s']G + [t]PA
352 * B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed
353 */
354
355 ECDSA_SIG_get0(sig, &r, &s);
356
357 if (BN_cmp(r, BN_value_one()) < 0
358 || BN_cmp(s, BN_value_one()) < 0
359 || BN_cmp(order, r) <= 0
360 || BN_cmp(order, s) <= 0) {
361 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
362 goto done;
363 }
364
365 if (!BN_mod_add(t, r, s, order, ctx)) {
366 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
367 goto done;
368 }
369
370 if (BN_is_zero(t)) {
371 ERR_raise(ERR_LIB_SM2, SM2_R_BAD_SIGNATURE);
372 goto done;
373 }
374
375 if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx)
376 || !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) {
377 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
378 goto done;
379 }
380
381 if (!BN_mod_add(t, e, x1, order, ctx)) {
382 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
383 goto done;
384 }
385
386 if (BN_cmp(r, t) == 0)
387 ret = 1;
388
389 done:
390 EC_POINT_free(pt);
391 BN_CTX_free(ctx);
392 return ret;
393 }
394
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)395 ECDSA_SIG *ossl_sm2_do_sign(const EC_KEY *key,
396 const EVP_MD *digest,
397 const uint8_t *id,
398 const size_t id_len,
399 const uint8_t *msg, size_t msg_len)
400 {
401 BIGNUM *e = NULL;
402 ECDSA_SIG *sig = NULL;
403
404 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
405 if (e == NULL) {
406 /* SM2err already called */
407 goto done;
408 }
409
410 sig = sm2_sig_gen(key, e);
411
412 done:
413 BN_free(e);
414 return sig;
415 }
416
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)417 int ossl_sm2_do_verify(const EC_KEY *key,
418 const EVP_MD *digest,
419 const ECDSA_SIG *sig,
420 const uint8_t *id,
421 const size_t id_len,
422 const uint8_t *msg, size_t msg_len)
423 {
424 BIGNUM *e = NULL;
425 int ret = 0;
426
427 e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len);
428 if (e == NULL) {
429 /* SM2err already called */
430 goto done;
431 }
432
433 ret = sm2_sig_verify(key, sig, e);
434
435 done:
436 BN_free(e);
437 return ret;
438 }
439
ossl_sm2_internal_sign(const unsigned char * dgst,int dgstlen,unsigned char * sig,unsigned int * siglen,EC_KEY * eckey)440 int ossl_sm2_internal_sign(const unsigned char *dgst, int dgstlen,
441 unsigned char *sig, unsigned int *siglen,
442 EC_KEY *eckey)
443 {
444 BIGNUM *e = NULL;
445 ECDSA_SIG *s = NULL;
446 int sigleni;
447 int ret = -1;
448
449 if (sig == NULL) {
450 ERR_raise(ERR_LIB_SM2, ERR_R_PASSED_NULL_PARAMETER);
451 goto done;
452 }
453
454 e = BN_bin2bn(dgst, dgstlen, NULL);
455 if (e == NULL) {
456 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
457 goto done;
458 }
459
460 s = sm2_sig_gen(eckey, e);
461 if (s == NULL) {
462 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
463 goto done;
464 }
465
466 sigleni = i2d_ECDSA_SIG(s, &sig);
467 if (sigleni < 0) {
468 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
469 goto done;
470 }
471 *siglen = (unsigned int)sigleni;
472
473 ret = 1;
474
475 done:
476 ECDSA_SIG_free(s);
477 BN_free(e);
478 return ret;
479 }
480
ossl_sm2_internal_verify(const unsigned char * dgst,int dgstlen,const unsigned char * sig,int sig_len,EC_KEY * eckey)481 int ossl_sm2_internal_verify(const unsigned char *dgst, int dgstlen,
482 const unsigned char *sig, int sig_len,
483 EC_KEY *eckey)
484 {
485 ECDSA_SIG *s = NULL;
486 BIGNUM *e = NULL;
487 const unsigned char *p = sig;
488 unsigned char *der = NULL;
489 int derlen = -1;
490 int ret = -1;
491
492 s = ECDSA_SIG_new();
493 if (s == NULL) {
494 ERR_raise(ERR_LIB_SM2, ERR_R_MALLOC_FAILURE);
495 goto done;
496 }
497 if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) {
498 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
499 goto done;
500 }
501 /* Ensure signature uses DER and doesn't have trailing garbage */
502 derlen = i2d_ECDSA_SIG(s, &der);
503 if (derlen != sig_len || memcmp(sig, der, derlen) != 0) {
504 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
505 goto done;
506 }
507
508 e = BN_bin2bn(dgst, dgstlen, NULL);
509 if (e == NULL) {
510 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
511 goto done;
512 }
513
514 ret = sm2_sig_verify(eckey, s, e);
515
516 done:
517 OPENSSL_free(der);
518 BN_free(e);
519 ECDSA_SIG_free(s);
520 return ret;
521 }
522