2 * Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.
3 * Copyright 2017 Ribose Inc. All Rights Reserved.
4 * Ported from Ribose contributions from Botan.
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
13 * ECDSA low level APIs are deprecated for public use, but still ok for
16 #include "internal/deprecated.h"
18 #include "crypto/sm2.h"
19 #include "crypto/sm2err.h"
20 #include "crypto/ec.h" /* ecdh_KDF_X9_63() */
21 #include <openssl/err.h>
22 #include <openssl/evp.h>
23 #include <openssl/bn.h>
24 #include <openssl/asn1.h>
25 #include <openssl/asn1t.h>
28 typedef struct SM2_Ciphertext_st SM2_Ciphertext
;
29 DECLARE_ASN1_FUNCTIONS(SM2_Ciphertext
)
31 struct SM2_Ciphertext_st
{
34 ASN1_OCTET_STRING
*C3
;
35 ASN1_OCTET_STRING
*C2
;
38 ASN1_SEQUENCE(SM2_Ciphertext
) = {
39 ASN1_SIMPLE(SM2_Ciphertext
, C1x
, BIGNUM
),
40 ASN1_SIMPLE(SM2_Ciphertext
, C1y
, BIGNUM
),
41 ASN1_SIMPLE(SM2_Ciphertext
, C3
, ASN1_OCTET_STRING
),
42 ASN1_SIMPLE(SM2_Ciphertext
, C2
, ASN1_OCTET_STRING
),
43 } ASN1_SEQUENCE_END(SM2_Ciphertext
)
45 IMPLEMENT_ASN1_FUNCTIONS(SM2_Ciphertext
)
47 static size_t ec_field_size(const EC_GROUP
*group
)
49 /* Is there some simpler way to do this? */
53 size_t field_size
= 0;
55 if (p
== NULL
|| a
== NULL
|| b
== NULL
)
58 if (!EC_GROUP_get_curve(group
, p
, a
, b
, NULL
))
60 field_size
= (BN_num_bits(p
) + 7) / 8;
70 int sm2_plaintext_size(const EC_KEY
*key
, const EVP_MD
*digest
, size_t msg_len
,
73 const size_t field_size
= ec_field_size(EC_KEY_get0_group(key
));
74 const int md_size
= EVP_MD_size(digest
);
78 ERR_raise(ERR_LIB_SM2
, SM2_R_INVALID_DIGEST
);
81 if (field_size
== 0) {
82 ERR_raise(ERR_LIB_SM2
, SM2_R_INVALID_FIELD
);
86 overhead
= 10 + 2 * field_size
+ (size_t)md_size
;
87 if (msg_len
<= overhead
) {
88 ERR_raise(ERR_LIB_SM2
, SM2_R_INVALID_ENCODING
);
92 *pt_size
= msg_len
- overhead
;
96 int sm2_ciphertext_size(const EC_KEY
*key
, const EVP_MD
*digest
, size_t msg_len
,
99 const size_t field_size
= ec_field_size(EC_KEY_get0_group(key
));
100 const int md_size
= EVP_MD_size(digest
);
103 if (field_size
== 0 || md_size
< 0)
106 /* Integer and string are simple type; set constructed = 0, means primitive and definite length encoding. */
107 sz
= 2 * ASN1_object_size(0, field_size
+ 1, V_ASN1_INTEGER
)
108 + ASN1_object_size(0, md_size
, V_ASN1_OCTET_STRING
)
109 + ASN1_object_size(0, msg_len
, V_ASN1_OCTET_STRING
);
110 /* Sequence is structured type; set constructed = 1, means constructed and definite length encoding. */
111 *ct_size
= ASN1_object_size(1, sz
, V_ASN1_SEQUENCE
);
116 int sm2_encrypt(const EC_KEY
*key
,
117 const EVP_MD
*digest
,
119 size_t msg_len
, uint8_t *ciphertext_buf
, size_t *ciphertext_len
)
121 int rc
= 0, ciphertext_leni
;
129 EVP_MD_CTX
*hash
= EVP_MD_CTX_new();
130 struct SM2_Ciphertext_st ctext_struct
;
131 const EC_GROUP
*group
= EC_KEY_get0_group(key
);
132 const BIGNUM
*order
= EC_GROUP_get0_order(group
);
133 const EC_POINT
*P
= EC_KEY_get0_public_key(key
);
136 uint8_t *msg_mask
= NULL
;
137 uint8_t *x2y2
= NULL
;
140 const int C3_size
= EVP_MD_size(digest
);
141 EVP_MD
*fetched_digest
= NULL
;
142 OSSL_LIB_CTX
*libctx
= ec_key_get_libctx(key
);
143 const char *propq
= ec_key_get0_propq(key
);
145 /* NULL these before any "goto done" */
146 ctext_struct
.C2
= NULL
;
147 ctext_struct
.C3
= NULL
;
149 if (hash
== NULL
|| C3_size
<= 0) {
150 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
154 field_size
= ec_field_size(group
);
155 if (field_size
== 0) {
156 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
160 kG
= EC_POINT_new(group
);
161 kP
= EC_POINT_new(group
);
162 ctx
= BN_CTX_new_ex(libctx
);
163 if (kG
== NULL
|| kP
== NULL
|| ctx
== NULL
) {
164 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
170 x1
= BN_CTX_get(ctx
);
171 x2
= BN_CTX_get(ctx
);
172 y1
= BN_CTX_get(ctx
);
173 y2
= BN_CTX_get(ctx
);
176 ERR_raise(ERR_LIB_SM2
, ERR_R_BN_LIB
);
180 x2y2
= OPENSSL_zalloc(2 * field_size
);
181 C3
= OPENSSL_zalloc(C3_size
);
183 if (x2y2
== NULL
|| C3
== NULL
) {
184 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
188 memset(ciphertext_buf
, 0, *ciphertext_len
);
190 if (!BN_priv_rand_range(k
, order
)) {
191 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
195 if (!EC_POINT_mul(group
, kG
, k
, NULL
, NULL
, ctx
)
196 || !EC_POINT_get_affine_coordinates(group
, kG
, x1
, y1
, ctx
)
197 || !EC_POINT_mul(group
, kP
, NULL
, P
, k
, ctx
)
198 || !EC_POINT_get_affine_coordinates(group
, kP
, x2
, y2
, ctx
)) {
199 ERR_raise(ERR_LIB_SM2
, ERR_R_EC_LIB
);
203 if (BN_bn2binpad(x2
, x2y2
, field_size
) < 0
204 || BN_bn2binpad(y2
, x2y2
+ field_size
, field_size
) < 0) {
205 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
209 msg_mask
= OPENSSL_zalloc(msg_len
);
210 if (msg_mask
== NULL
) {
211 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
215 /* X9.63 with no salt happens to match the KDF used in SM2 */
216 if (!ecdh_KDF_X9_63(msg_mask
, msg_len
, x2y2
, 2 * field_size
, NULL
, 0,
217 digest
, libctx
, propq
)) {
218 ERR_raise(ERR_LIB_SM2
, ERR_R_EVP_LIB
);
222 for (i
= 0; i
!= msg_len
; ++i
)
223 msg_mask
[i
] ^= msg
[i
];
225 fetched_digest
= EVP_MD_fetch(libctx
, EVP_MD_name(digest
), propq
);
226 if (fetched_digest
== NULL
) {
227 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
230 if (EVP_DigestInit(hash
, fetched_digest
) == 0
231 || EVP_DigestUpdate(hash
, x2y2
, field_size
) == 0
232 || EVP_DigestUpdate(hash
, msg
, msg_len
) == 0
233 || EVP_DigestUpdate(hash
, x2y2
+ field_size
, field_size
) == 0
234 || EVP_DigestFinal(hash
, C3
, NULL
) == 0) {
235 ERR_raise(ERR_LIB_SM2
, ERR_R_EVP_LIB
);
239 ctext_struct
.C1x
= x1
;
240 ctext_struct
.C1y
= y1
;
241 ctext_struct
.C3
= ASN1_OCTET_STRING_new();
242 ctext_struct
.C2
= ASN1_OCTET_STRING_new();
244 if (ctext_struct
.C3
== NULL
|| ctext_struct
.C2
== NULL
) {
245 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
248 if (!ASN1_OCTET_STRING_set(ctext_struct
.C3
, C3
, C3_size
)
249 || !ASN1_OCTET_STRING_set(ctext_struct
.C2
, msg_mask
, msg_len
)) {
250 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
254 ciphertext_leni
= i2d_SM2_Ciphertext(&ctext_struct
, &ciphertext_buf
);
255 /* Ensure cast to size_t is safe */
256 if (ciphertext_leni
< 0) {
257 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
260 *ciphertext_len
= (size_t)ciphertext_leni
;
265 EVP_MD_free(fetched_digest
);
266 ASN1_OCTET_STRING_free(ctext_struct
.C2
);
267 ASN1_OCTET_STRING_free(ctext_struct
.C3
);
268 OPENSSL_free(msg_mask
);
271 EVP_MD_CTX_free(hash
);
278 int sm2_decrypt(const EC_KEY
*key
,
279 const EVP_MD
*digest
,
280 const uint8_t *ciphertext
,
281 size_t ciphertext_len
, uint8_t *ptext_buf
, size_t *ptext_len
)
286 const EC_GROUP
*group
= EC_KEY_get0_group(key
);
288 struct SM2_Ciphertext_st
*sm2_ctext
= NULL
;
291 uint8_t *x2y2
= NULL
;
292 uint8_t *computed_C3
= NULL
;
293 const size_t field_size
= ec_field_size(group
);
294 const int hash_size
= EVP_MD_size(digest
);
295 uint8_t *msg_mask
= NULL
;
296 const uint8_t *C2
= NULL
;
297 const uint8_t *C3
= NULL
;
299 EVP_MD_CTX
*hash
= NULL
;
300 OSSL_LIB_CTX
*libctx
= ec_key_get_libctx(key
);
301 const char *propq
= ec_key_get0_propq(key
);
303 if (field_size
== 0 || hash_size
<= 0)
306 memset(ptext_buf
, 0xFF, *ptext_len
);
308 sm2_ctext
= d2i_SM2_Ciphertext(NULL
, &ciphertext
, ciphertext_len
);
310 if (sm2_ctext
== NULL
) {
311 ERR_raise(ERR_LIB_SM2
, SM2_R_ASN1_ERROR
);
315 if (sm2_ctext
->C3
->length
!= hash_size
) {
316 ERR_raise(ERR_LIB_SM2
, SM2_R_INVALID_ENCODING
);
320 C2
= sm2_ctext
->C2
->data
;
321 C3
= sm2_ctext
->C3
->data
;
322 msg_len
= sm2_ctext
->C2
->length
;
324 ctx
= BN_CTX_new_ex(libctx
);
326 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
331 x2
= BN_CTX_get(ctx
);
332 y2
= BN_CTX_get(ctx
);
335 ERR_raise(ERR_LIB_SM2
, ERR_R_BN_LIB
);
339 msg_mask
= OPENSSL_zalloc(msg_len
);
340 x2y2
= OPENSSL_zalloc(2 * field_size
);
341 computed_C3
= OPENSSL_zalloc(hash_size
);
343 if (msg_mask
== NULL
|| x2y2
== NULL
|| computed_C3
== NULL
) {
344 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
348 C1
= EC_POINT_new(group
);
350 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
354 if (!EC_POINT_set_affine_coordinates(group
, C1
, sm2_ctext
->C1x
,
356 || !EC_POINT_mul(group
, C1
, NULL
, C1
, EC_KEY_get0_private_key(key
),
358 || !EC_POINT_get_affine_coordinates(group
, C1
, x2
, y2
, ctx
)) {
359 ERR_raise(ERR_LIB_SM2
, ERR_R_EC_LIB
);
363 if (BN_bn2binpad(x2
, x2y2
, field_size
) < 0
364 || BN_bn2binpad(y2
, x2y2
+ field_size
, field_size
) < 0
365 || !ecdh_KDF_X9_63(msg_mask
, msg_len
, x2y2
, 2 * field_size
, NULL
, 0,
366 digest
, libctx
, propq
)) {
367 ERR_raise(ERR_LIB_SM2
, ERR_R_INTERNAL_ERROR
);
371 for (i
= 0; i
!= msg_len
; ++i
)
372 ptext_buf
[i
] = C2
[i
] ^ msg_mask
[i
];
374 hash
= EVP_MD_CTX_new();
376 ERR_raise(ERR_LIB_SM2
, ERR_R_MALLOC_FAILURE
);
380 if (!EVP_DigestInit(hash
, digest
)
381 || !EVP_DigestUpdate(hash
, x2y2
, field_size
)
382 || !EVP_DigestUpdate(hash
, ptext_buf
, msg_len
)
383 || !EVP_DigestUpdate(hash
, x2y2
+ field_size
, field_size
)
384 || !EVP_DigestFinal(hash
, computed_C3
, NULL
)) {
385 ERR_raise(ERR_LIB_SM2
, ERR_R_EVP_LIB
);
389 if (CRYPTO_memcmp(computed_C3
, C3
, hash_size
) != 0) {
390 ERR_raise(ERR_LIB_SM2
, SM2_R_INVALID_DIGEST
);
395 *ptext_len
= msg_len
;
399 memset(ptext_buf
, 0, *ptext_len
);
401 OPENSSL_free(msg_mask
);
403 OPENSSL_free(computed_C3
);
406 SM2_Ciphertext_free(sm2_ctext
);
407 EVP_MD_CTX_free(hash
);