1 | /* |
2 | * Copyright 2017-2018 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 "crypto/sm2.h" |
13 | #include "crypto/sm2err.h" |
14 | #include "crypto/ec.h" /* ec_group_do_inverse_ord() */ |
15 | #include "internal/numbers.h" |
16 | #include <openssl/err.h> |
17 | #include <openssl/evp.h> |
18 | #include <openssl/err.h> |
19 | #include <openssl/bn.h> |
20 | #include <string.h> |
21 | |
22 | int sm2_compute_z_digest(uint8_t *out, |
23 | const EVP_MD *digest, |
24 | const uint8_t *id, |
25 | const size_t id_len, |
26 | const EC_KEY *key) |
27 | { |
28 | int rc = 0; |
29 | const EC_GROUP *group = EC_KEY_get0_group(key); |
30 | BN_CTX *ctx = NULL; |
31 | EVP_MD_CTX *hash = NULL; |
32 | BIGNUM *p = NULL; |
33 | BIGNUM *a = NULL; |
34 | BIGNUM *b = NULL; |
35 | BIGNUM *xG = NULL; |
36 | BIGNUM *yG = NULL; |
37 | BIGNUM *xA = NULL; |
38 | BIGNUM *yA = NULL; |
39 | int p_bytes = 0; |
40 | uint8_t *buf = NULL; |
41 | uint16_t entl = 0; |
42 | uint8_t e_byte = 0; |
43 | |
44 | hash = EVP_MD_CTX_new(); |
45 | ctx = BN_CTX_new(); |
46 | if (hash == NULL || ctx == NULL) { |
47 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_MALLOC_FAILURE); |
48 | goto done; |
49 | } |
50 | |
51 | p = BN_CTX_get(ctx); |
52 | a = BN_CTX_get(ctx); |
53 | b = BN_CTX_get(ctx); |
54 | xG = BN_CTX_get(ctx); |
55 | yG = BN_CTX_get(ctx); |
56 | xA = BN_CTX_get(ctx); |
57 | yA = BN_CTX_get(ctx); |
58 | |
59 | if (yA == NULL) { |
60 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_MALLOC_FAILURE); |
61 | goto done; |
62 | } |
63 | |
64 | if (!EVP_DigestInit(hash, digest)) { |
65 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); |
66 | goto done; |
67 | } |
68 | |
69 | /* Z = h(ENTL || ID || a || b || xG || yG || xA || yA) */ |
70 | |
71 | if (id_len >= (UINT16_MAX / 8)) { |
72 | /* too large */ |
73 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, SM2_R_ID_TOO_LARGE); |
74 | goto done; |
75 | } |
76 | |
77 | entl = (uint16_t)(8 * id_len); |
78 | |
79 | e_byte = entl >> 8; |
80 | if (!EVP_DigestUpdate(hash, &e_byte, 1)) { |
81 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); |
82 | goto done; |
83 | } |
84 | e_byte = entl & 0xFF; |
85 | if (!EVP_DigestUpdate(hash, &e_byte, 1)) { |
86 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); |
87 | goto done; |
88 | } |
89 | |
90 | if (id_len > 0 && !EVP_DigestUpdate(hash, id, id_len)) { |
91 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EVP_LIB); |
92 | goto done; |
93 | } |
94 | |
95 | if (!EC_GROUP_get_curve(group, p, a, b, ctx)) { |
96 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_EC_LIB); |
97 | goto done; |
98 | } |
99 | |
100 | p_bytes = BN_num_bytes(p); |
101 | buf = OPENSSL_zalloc(p_bytes); |
102 | if (buf == NULL) { |
103 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_MALLOC_FAILURE); |
104 | goto done; |
105 | } |
106 | |
107 | if (BN_bn2binpad(a, buf, p_bytes) < 0 |
108 | || !EVP_DigestUpdate(hash, buf, p_bytes) |
109 | || BN_bn2binpad(b, buf, p_bytes) < 0 |
110 | || !EVP_DigestUpdate(hash, buf, p_bytes) |
111 | || !EC_POINT_get_affine_coordinates(group, |
112 | EC_GROUP_get0_generator(group), |
113 | xG, yG, ctx) |
114 | || BN_bn2binpad(xG, buf, p_bytes) < 0 |
115 | || !EVP_DigestUpdate(hash, buf, p_bytes) |
116 | || BN_bn2binpad(yG, buf, p_bytes) < 0 |
117 | || !EVP_DigestUpdate(hash, buf, p_bytes) |
118 | || !EC_POINT_get_affine_coordinates(group, |
119 | EC_KEY_get0_public_key(key), |
120 | xA, yA, ctx) |
121 | || BN_bn2binpad(xA, buf, p_bytes) < 0 |
122 | || !EVP_DigestUpdate(hash, buf, p_bytes) |
123 | || BN_bn2binpad(yA, buf, p_bytes) < 0 |
124 | || !EVP_DigestUpdate(hash, buf, p_bytes) |
125 | || !EVP_DigestFinal(hash, out, NULL)) { |
126 | SM2err(SM2_F_SM2_COMPUTE_Z_DIGEST, ERR_R_INTERNAL_ERROR); |
127 | goto done; |
128 | } |
129 | |
130 | rc = 1; |
131 | |
132 | done: |
133 | OPENSSL_free(buf); |
134 | BN_CTX_free(ctx); |
135 | EVP_MD_CTX_free(hash); |
136 | return rc; |
137 | } |
138 | |
139 | static BIGNUM *sm2_compute_msg_hash(const EVP_MD *digest, |
140 | const EC_KEY *key, |
141 | const uint8_t *id, |
142 | const size_t id_len, |
143 | const uint8_t *msg, size_t msg_len) |
144 | { |
145 | EVP_MD_CTX *hash = EVP_MD_CTX_new(); |
146 | const int md_size = EVP_MD_size(digest); |
147 | uint8_t *z = NULL; |
148 | BIGNUM *e = NULL; |
149 | |
150 | if (md_size < 0) { |
151 | SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, SM2_R_INVALID_DIGEST); |
152 | goto done; |
153 | } |
154 | |
155 | z = OPENSSL_zalloc(md_size); |
156 | if (hash == NULL || z == NULL) { |
157 | SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, ERR_R_MALLOC_FAILURE); |
158 | goto done; |
159 | } |
160 | |
161 | if (!sm2_compute_z_digest(z, digest, id, id_len, key)) { |
162 | /* SM2err already called */ |
163 | goto done; |
164 | } |
165 | |
166 | if (!EVP_DigestInit(hash, digest) |
167 | || !EVP_DigestUpdate(hash, z, md_size) |
168 | || !EVP_DigestUpdate(hash, msg, msg_len) |
169 | /* reuse z buffer to hold H(Z || M) */ |
170 | || !EVP_DigestFinal(hash, z, NULL)) { |
171 | SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, ERR_R_EVP_LIB); |
172 | goto done; |
173 | } |
174 | |
175 | e = BN_bin2bn(z, md_size, NULL); |
176 | if (e == NULL) |
177 | SM2err(SM2_F_SM2_COMPUTE_MSG_HASH, ERR_R_INTERNAL_ERROR); |
178 | |
179 | done: |
180 | OPENSSL_free(z); |
181 | EVP_MD_CTX_free(hash); |
182 | return e; |
183 | } |
184 | |
185 | static ECDSA_SIG *sm2_sig_gen(const EC_KEY *key, const BIGNUM *e) |
186 | { |
187 | const BIGNUM *dA = EC_KEY_get0_private_key(key); |
188 | const EC_GROUP *group = EC_KEY_get0_group(key); |
189 | const BIGNUM *order = EC_GROUP_get0_order(group); |
190 | ECDSA_SIG *sig = NULL; |
191 | EC_POINT *kG = NULL; |
192 | BN_CTX *ctx = NULL; |
193 | BIGNUM *k = NULL; |
194 | BIGNUM *rk = NULL; |
195 | BIGNUM *r = NULL; |
196 | BIGNUM *s = NULL; |
197 | BIGNUM *x1 = NULL; |
198 | BIGNUM *tmp = NULL; |
199 | |
200 | kG = EC_POINT_new(group); |
201 | ctx = BN_CTX_new(); |
202 | if (kG == NULL || ctx == NULL) { |
203 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); |
204 | goto done; |
205 | } |
206 | |
207 | BN_CTX_start(ctx); |
208 | k = BN_CTX_get(ctx); |
209 | rk = BN_CTX_get(ctx); |
210 | x1 = BN_CTX_get(ctx); |
211 | tmp = BN_CTX_get(ctx); |
212 | if (tmp == NULL) { |
213 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); |
214 | goto done; |
215 | } |
216 | |
217 | /* |
218 | * These values are returned and so should not be allocated out of the |
219 | * context |
220 | */ |
221 | r = BN_new(); |
222 | s = BN_new(); |
223 | |
224 | if (r == NULL || s == NULL) { |
225 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); |
226 | goto done; |
227 | } |
228 | |
229 | for (;;) { |
230 | if (!BN_priv_rand_range(k, order)) { |
231 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_INTERNAL_ERROR); |
232 | goto done; |
233 | } |
234 | |
235 | if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx) |
236 | || !EC_POINT_get_affine_coordinates(group, kG, x1, NULL, |
237 | ctx) |
238 | || !BN_mod_add(r, e, x1, order, ctx)) { |
239 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_INTERNAL_ERROR); |
240 | goto done; |
241 | } |
242 | |
243 | /* try again if r == 0 or r+k == n */ |
244 | if (BN_is_zero(r)) |
245 | continue; |
246 | |
247 | if (!BN_add(rk, r, k)) { |
248 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_INTERNAL_ERROR); |
249 | goto done; |
250 | } |
251 | |
252 | if (BN_cmp(rk, order) == 0) |
253 | continue; |
254 | |
255 | if (!BN_add(s, dA, BN_value_one()) |
256 | || !ec_group_do_inverse_ord(group, s, s, ctx) |
257 | || !BN_mod_mul(tmp, dA, r, order, ctx) |
258 | || !BN_sub(tmp, k, tmp) |
259 | || !BN_mod_mul(s, s, tmp, order, ctx)) { |
260 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_BN_LIB); |
261 | goto done; |
262 | } |
263 | |
264 | sig = ECDSA_SIG_new(); |
265 | if (sig == NULL) { |
266 | SM2err(SM2_F_SM2_SIG_GEN, ERR_R_MALLOC_FAILURE); |
267 | goto done; |
268 | } |
269 | |
270 | /* takes ownership of r and s */ |
271 | ECDSA_SIG_set0(sig, r, s); |
272 | break; |
273 | } |
274 | |
275 | done: |
276 | if (sig == NULL) { |
277 | BN_free(r); |
278 | BN_free(s); |
279 | } |
280 | |
281 | BN_CTX_free(ctx); |
282 | EC_POINT_free(kG); |
283 | return sig; |
284 | } |
285 | |
286 | static int sm2_sig_verify(const EC_KEY *key, const ECDSA_SIG *sig, |
287 | const BIGNUM *e) |
288 | { |
289 | int ret = 0; |
290 | const EC_GROUP *group = EC_KEY_get0_group(key); |
291 | const BIGNUM *order = EC_GROUP_get0_order(group); |
292 | BN_CTX *ctx = NULL; |
293 | EC_POINT *pt = NULL; |
294 | BIGNUM *t = NULL; |
295 | BIGNUM *x1 = NULL; |
296 | const BIGNUM *r = NULL; |
297 | const BIGNUM *s = NULL; |
298 | |
299 | ctx = BN_CTX_new(); |
300 | pt = EC_POINT_new(group); |
301 | if (ctx == NULL || pt == NULL) { |
302 | SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_MALLOC_FAILURE); |
303 | goto done; |
304 | } |
305 | |
306 | BN_CTX_start(ctx); |
307 | t = BN_CTX_get(ctx); |
308 | x1 = BN_CTX_get(ctx); |
309 | if (x1 == NULL) { |
310 | SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_MALLOC_FAILURE); |
311 | goto done; |
312 | } |
313 | |
314 | /* |
315 | * B1: verify whether r' in [1,n-1], verification failed if not |
316 | * B2: verify whether s' in [1,n-1], verification failed if not |
317 | * B3: set M'~=ZA || M' |
318 | * B4: calculate e'=Hv(M'~) |
319 | * B5: calculate t = (r' + s') modn, verification failed if t=0 |
320 | * B6: calculate the point (x1', y1')=[s']G + [t]PA |
321 | * B7: calculate R=(e'+x1') modn, verification pass if yes, otherwise failed |
322 | */ |
323 | |
324 | ECDSA_SIG_get0(sig, &r, &s); |
325 | |
326 | if (BN_cmp(r, BN_value_one()) < 0 |
327 | || BN_cmp(s, BN_value_one()) < 0 |
328 | || BN_cmp(order, r) <= 0 |
329 | || BN_cmp(order, s) <= 0) { |
330 | SM2err(SM2_F_SM2_SIG_VERIFY, SM2_R_BAD_SIGNATURE); |
331 | goto done; |
332 | } |
333 | |
334 | if (!BN_mod_add(t, r, s, order, ctx)) { |
335 | SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_BN_LIB); |
336 | goto done; |
337 | } |
338 | |
339 | if (BN_is_zero(t)) { |
340 | SM2err(SM2_F_SM2_SIG_VERIFY, SM2_R_BAD_SIGNATURE); |
341 | goto done; |
342 | } |
343 | |
344 | if (!EC_POINT_mul(group, pt, s, EC_KEY_get0_public_key(key), t, ctx) |
345 | || !EC_POINT_get_affine_coordinates(group, pt, x1, NULL, ctx)) { |
346 | SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_EC_LIB); |
347 | goto done; |
348 | } |
349 | |
350 | if (!BN_mod_add(t, e, x1, order, ctx)) { |
351 | SM2err(SM2_F_SM2_SIG_VERIFY, ERR_R_BN_LIB); |
352 | goto done; |
353 | } |
354 | |
355 | if (BN_cmp(r, t) == 0) |
356 | ret = 1; |
357 | |
358 | done: |
359 | EC_POINT_free(pt); |
360 | BN_CTX_free(ctx); |
361 | return ret; |
362 | } |
363 | |
364 | ECDSA_SIG *sm2_do_sign(const EC_KEY *key, |
365 | const EVP_MD *digest, |
366 | const uint8_t *id, |
367 | const size_t id_len, |
368 | const uint8_t *msg, size_t msg_len) |
369 | { |
370 | BIGNUM *e = NULL; |
371 | ECDSA_SIG *sig = NULL; |
372 | |
373 | e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len); |
374 | if (e == NULL) { |
375 | /* SM2err already called */ |
376 | goto done; |
377 | } |
378 | |
379 | sig = sm2_sig_gen(key, e); |
380 | |
381 | done: |
382 | BN_free(e); |
383 | return sig; |
384 | } |
385 | |
386 | int sm2_do_verify(const EC_KEY *key, |
387 | const EVP_MD *digest, |
388 | const ECDSA_SIG *sig, |
389 | const uint8_t *id, |
390 | const size_t id_len, |
391 | const uint8_t *msg, size_t msg_len) |
392 | { |
393 | BIGNUM *e = NULL; |
394 | int ret = 0; |
395 | |
396 | e = sm2_compute_msg_hash(digest, key, id, id_len, msg, msg_len); |
397 | if (e == NULL) { |
398 | /* SM2err already called */ |
399 | goto done; |
400 | } |
401 | |
402 | ret = sm2_sig_verify(key, sig, e); |
403 | |
404 | done: |
405 | BN_free(e); |
406 | return ret; |
407 | } |
408 | |
409 | int sm2_sign(const unsigned char *dgst, int dgstlen, |
410 | unsigned char *sig, unsigned int *siglen, EC_KEY *eckey) |
411 | { |
412 | BIGNUM *e = NULL; |
413 | ECDSA_SIG *s = NULL; |
414 | int sigleni; |
415 | int ret = -1; |
416 | |
417 | e = BN_bin2bn(dgst, dgstlen, NULL); |
418 | if (e == NULL) { |
419 | SM2err(SM2_F_SM2_SIGN, ERR_R_BN_LIB); |
420 | goto done; |
421 | } |
422 | |
423 | s = sm2_sig_gen(eckey, e); |
424 | |
425 | sigleni = i2d_ECDSA_SIG(s, &sig); |
426 | if (sigleni < 0) { |
427 | SM2err(SM2_F_SM2_SIGN, ERR_R_INTERNAL_ERROR); |
428 | goto done; |
429 | } |
430 | *siglen = (unsigned int)sigleni; |
431 | |
432 | ret = 1; |
433 | |
434 | done: |
435 | ECDSA_SIG_free(s); |
436 | BN_free(e); |
437 | return ret; |
438 | } |
439 | |
440 | int sm2_verify(const unsigned char *dgst, int dgstlen, |
441 | const unsigned char *sig, int sig_len, EC_KEY *eckey) |
442 | { |
443 | ECDSA_SIG *s = NULL; |
444 | BIGNUM *e = NULL; |
445 | const unsigned char *p = sig; |
446 | unsigned char *der = NULL; |
447 | int derlen = -1; |
448 | int ret = -1; |
449 | |
450 | s = ECDSA_SIG_new(); |
451 | if (s == NULL) { |
452 | SM2err(SM2_F_SM2_VERIFY, ERR_R_MALLOC_FAILURE); |
453 | goto done; |
454 | } |
455 | if (d2i_ECDSA_SIG(&s, &p, sig_len) == NULL) { |
456 | SM2err(SM2_F_SM2_VERIFY, SM2_R_INVALID_ENCODING); |
457 | goto done; |
458 | } |
459 | /* Ensure signature uses DER and doesn't have trailing garbage */ |
460 | derlen = i2d_ECDSA_SIG(s, &der); |
461 | if (derlen != sig_len || memcmp(sig, der, derlen) != 0) { |
462 | SM2err(SM2_F_SM2_VERIFY, SM2_R_INVALID_ENCODING); |
463 | goto done; |
464 | } |
465 | |
466 | e = BN_bin2bn(dgst, dgstlen, NULL); |
467 | if (e == NULL) { |
468 | SM2err(SM2_F_SM2_VERIFY, ERR_R_BN_LIB); |
469 | goto done; |
470 | } |
471 | |
472 | ret = sm2_sig_verify(eckey, s, e); |
473 | |
474 | done: |
475 | OPENSSL_free(der); |
476 | BN_free(e); |
477 | ECDSA_SIG_free(s); |
478 | return ret; |
479 | } |
480 | |