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.
6 * Licensed under the OpenSSL license (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
12 #include "internal/sm2.h"
13 #include "internal/sm2err.h"
14 #include "internal/ec_int.h" /* ecdh_KDF_X9_63() */
15 #include <openssl/err.h>
16 #include <openssl/evp.h>
17 #include <openssl/bn.h>
18 #include <openssl/asn1.h>
19 #include <openssl/asn1t.h>
22 typedef struct SM2_Ciphertext_st SM2_Ciphertext
;
23 DECLARE_ASN1_FUNCTIONS(SM2_Ciphertext
)
25 struct SM2_Ciphertext_st
{
28 ASN1_OCTET_STRING
*C3
;
29 ASN1_OCTET_STRING
*C2
;
32 ASN1_SEQUENCE(SM2_Ciphertext
) = {
33 ASN1_SIMPLE(SM2_Ciphertext
, C1x
, BIGNUM
),
34 ASN1_SIMPLE(SM2_Ciphertext
, C1y
, BIGNUM
),
35 ASN1_SIMPLE(SM2_Ciphertext
, C3
, ASN1_OCTET_STRING
),
36 ASN1_SIMPLE(SM2_Ciphertext
, C2
, ASN1_OCTET_STRING
),
37 } ASN1_SEQUENCE_END(SM2_Ciphertext
)
39 IMPLEMENT_ASN1_FUNCTIONS(SM2_Ciphertext
)
41 static size_t ec_field_size(const EC_GROUP
*group
)
43 /* Is there some simpler way to do this? */
47 size_t field_size
= 0;
49 if (p
== NULL
|| a
== NULL
|| b
== NULL
)
52 if (!EC_GROUP_get_curve(group
, p
, a
, b
, NULL
))
54 field_size
= (BN_num_bits(p
) + 7) / 8;
64 int sm2_plaintext_size(const EC_KEY
*key
, const EVP_MD
*digest
, size_t msg_len
,
67 const size_t field_size
= ec_field_size(EC_KEY_get0_group(key
));
68 const int md_size
= EVP_MD_size(digest
);
72 SM2err(SM2_F_SM2_PLAINTEXT_SIZE
, SM2_R_INVALID_DIGEST
);
75 if (field_size
== 0) {
76 SM2err(SM2_F_SM2_PLAINTEXT_SIZE
, SM2_R_INVALID_FIELD
);
80 overhead
= 10 + 2 * field_size
+ (size_t)md_size
;
81 if (msg_len
<= overhead
) {
82 SM2err(SM2_F_SM2_PLAINTEXT_SIZE
, SM2_R_INVALID_ENCODING
);
86 *pt_size
= msg_len
- overhead
;
90 int sm2_ciphertext_size(const EC_KEY
*key
, const EVP_MD
*digest
, size_t msg_len
,
93 const size_t field_size
= ec_field_size(EC_KEY_get0_group(key
));
94 const int md_size
= EVP_MD_size(digest
);
97 if (field_size
== 0 || md_size
< 0)
100 /* Integer and string are simple type; set constructed = 0, means primitive and definite length encoding. */
101 sz
= 2 * ASN1_object_size(0, field_size
+ 1, V_ASN1_INTEGER
)
102 + ASN1_object_size(0, md_size
, V_ASN1_OCTET_STRING
)
103 + ASN1_object_size(0, msg_len
, V_ASN1_OCTET_STRING
);
104 /* Sequence is structured type; set constructed = 1, means constructed and definite length encoding. */
105 *ct_size
= ASN1_object_size(1, sz
, V_ASN1_SEQUENCE
);
110 int sm2_encrypt(const EC_KEY
*key
,
111 const EVP_MD
*digest
,
113 size_t msg_len
, uint8_t *ciphertext_buf
, size_t *ciphertext_len
)
115 int rc
= 0, ciphertext_leni
;
123 EVP_MD_CTX
*hash
= EVP_MD_CTX_new();
124 struct SM2_Ciphertext_st ctext_struct
;
125 const EC_GROUP
*group
= EC_KEY_get0_group(key
);
126 const BIGNUM
*order
= EC_GROUP_get0_order(group
);
127 const EC_POINT
*P
= EC_KEY_get0_public_key(key
);
130 uint8_t *msg_mask
= NULL
;
131 uint8_t *x2y2
= NULL
;
134 const int C3_size
= EVP_MD_size(digest
);
136 /* NULL these before any "goto done" */
137 ctext_struct
.C2
= NULL
;
138 ctext_struct
.C3
= NULL
;
140 if (hash
== NULL
|| C3_size
<= 0) {
141 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_INTERNAL_ERROR
);
145 field_size
= ec_field_size(group
);
146 if (field_size
== 0) {
147 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_INTERNAL_ERROR
);
151 kG
= EC_POINT_new(group
);
152 kP
= EC_POINT_new(group
);
154 if (kG
== NULL
|| kP
== NULL
|| ctx
== NULL
) {
155 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_MALLOC_FAILURE
);
161 x1
= BN_CTX_get(ctx
);
162 x2
= BN_CTX_get(ctx
);
163 y1
= BN_CTX_get(ctx
);
164 y2
= BN_CTX_get(ctx
);
167 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_BN_LIB
);
171 x2y2
= OPENSSL_zalloc(2 * field_size
);
172 C3
= OPENSSL_zalloc(C3_size
);
174 if (x2y2
== NULL
|| C3
== NULL
) {
175 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_MALLOC_FAILURE
);
179 memset(ciphertext_buf
, 0, *ciphertext_len
);
181 if (!BN_priv_rand_range(k
, order
)) {
182 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_INTERNAL_ERROR
);
186 if (!EC_POINT_mul(group
, kG
, k
, NULL
, NULL
, ctx
)
187 || !EC_POINT_get_affine_coordinates(group
, kG
, x1
, y1
, ctx
)
188 || !EC_POINT_mul(group
, kP
, NULL
, P
, k
, ctx
)
189 || !EC_POINT_get_affine_coordinates(group
, kP
, x2
, y2
, ctx
)) {
190 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_EC_LIB
);
194 if (BN_bn2binpad(x2
, x2y2
, field_size
) < 0
195 || BN_bn2binpad(y2
, x2y2
+ field_size
, field_size
) < 0) {
196 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_INTERNAL_ERROR
);
200 msg_mask
= OPENSSL_zalloc(msg_len
);
201 if (msg_mask
== NULL
) {
202 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_MALLOC_FAILURE
);
206 /* X9.63 with no salt happens to match the KDF used in SM2 */
207 if (!ecdh_KDF_X9_63(msg_mask
, msg_len
, x2y2
, 2 * field_size
, NULL
, 0,
209 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_EVP_LIB
);
213 for (i
= 0; i
!= msg_len
; ++i
)
214 msg_mask
[i
] ^= msg
[i
];
216 if (EVP_DigestInit(hash
, digest
) == 0
217 || EVP_DigestUpdate(hash
, x2y2
, field_size
) == 0
218 || EVP_DigestUpdate(hash
, msg
, msg_len
) == 0
219 || EVP_DigestUpdate(hash
, x2y2
+ field_size
, field_size
) == 0
220 || EVP_DigestFinal(hash
, C3
, NULL
) == 0) {
221 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_EVP_LIB
);
225 ctext_struct
.C1x
= x1
;
226 ctext_struct
.C1y
= y1
;
227 ctext_struct
.C3
= ASN1_OCTET_STRING_new();
228 ctext_struct
.C2
= ASN1_OCTET_STRING_new();
230 if (ctext_struct
.C3
== NULL
|| ctext_struct
.C2
== NULL
) {
231 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_MALLOC_FAILURE
);
234 if (!ASN1_OCTET_STRING_set(ctext_struct
.C3
, C3
, C3_size
)
235 || !ASN1_OCTET_STRING_set(ctext_struct
.C2
, msg_mask
, msg_len
)) {
236 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_INTERNAL_ERROR
);
240 ciphertext_leni
= i2d_SM2_Ciphertext(&ctext_struct
, &ciphertext_buf
);
241 /* Ensure cast to size_t is safe */
242 if (ciphertext_leni
< 0) {
243 SM2err(SM2_F_SM2_ENCRYPT
, ERR_R_INTERNAL_ERROR
);
246 *ciphertext_len
= (size_t)ciphertext_leni
;
251 ASN1_OCTET_STRING_free(ctext_struct
.C2
);
252 ASN1_OCTET_STRING_free(ctext_struct
.C3
);
253 OPENSSL_free(msg_mask
);
256 EVP_MD_CTX_free(hash
);
263 int sm2_decrypt(const EC_KEY
*key
,
264 const EVP_MD
*digest
,
265 const uint8_t *ciphertext
,
266 size_t ciphertext_len
, uint8_t *ptext_buf
, size_t *ptext_len
)
271 const EC_GROUP
*group
= EC_KEY_get0_group(key
);
273 struct SM2_Ciphertext_st
*sm2_ctext
= NULL
;
276 uint8_t *x2y2
= NULL
;
277 uint8_t *computed_C3
= NULL
;
278 const size_t field_size
= ec_field_size(group
);
279 const int hash_size
= EVP_MD_size(digest
);
280 uint8_t *msg_mask
= NULL
;
281 const uint8_t *C2
= NULL
;
282 const uint8_t *C3
= NULL
;
284 EVP_MD_CTX
*hash
= NULL
;
286 if (field_size
== 0 || hash_size
<= 0)
289 memset(ptext_buf
, 0xFF, *ptext_len
);
291 sm2_ctext
= d2i_SM2_Ciphertext(NULL
, &ciphertext
, ciphertext_len
);
293 if (sm2_ctext
== NULL
) {
294 SM2err(SM2_F_SM2_DECRYPT
, SM2_R_ASN1_ERROR
);
298 if (sm2_ctext
->C3
->length
!= hash_size
) {
299 SM2err(SM2_F_SM2_DECRYPT
, SM2_R_INVALID_ENCODING
);
303 C2
= sm2_ctext
->C2
->data
;
304 C3
= sm2_ctext
->C3
->data
;
305 msg_len
= sm2_ctext
->C2
->length
;
309 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_MALLOC_FAILURE
);
314 x2
= BN_CTX_get(ctx
);
315 y2
= BN_CTX_get(ctx
);
318 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_BN_LIB
);
322 msg_mask
= OPENSSL_zalloc(msg_len
);
323 x2y2
= OPENSSL_zalloc(2 * field_size
);
324 computed_C3
= OPENSSL_zalloc(hash_size
);
326 if (msg_mask
== NULL
|| x2y2
== NULL
|| computed_C3
== NULL
) {
327 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_MALLOC_FAILURE
);
331 C1
= EC_POINT_new(group
);
333 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_MALLOC_FAILURE
);
337 if (!EC_POINT_set_affine_coordinates(group
, C1
, sm2_ctext
->C1x
,
339 || !EC_POINT_mul(group
, C1
, NULL
, C1
, EC_KEY_get0_private_key(key
),
341 || !EC_POINT_get_affine_coordinates(group
, C1
, x2
, y2
, ctx
)) {
342 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_EC_LIB
);
346 if (BN_bn2binpad(x2
, x2y2
, field_size
) < 0
347 || BN_bn2binpad(y2
, x2y2
+ field_size
, field_size
) < 0
348 || !ecdh_KDF_X9_63(msg_mask
, msg_len
, x2y2
, 2 * field_size
, NULL
, 0,
350 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_INTERNAL_ERROR
);
354 for (i
= 0; i
!= msg_len
; ++i
)
355 ptext_buf
[i
] = C2
[i
] ^ msg_mask
[i
];
357 hash
= EVP_MD_CTX_new();
359 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_MALLOC_FAILURE
);
363 if (!EVP_DigestInit(hash
, digest
)
364 || !EVP_DigestUpdate(hash
, x2y2
, field_size
)
365 || !EVP_DigestUpdate(hash
, ptext_buf
, msg_len
)
366 || !EVP_DigestUpdate(hash
, x2y2
+ field_size
, field_size
)
367 || !EVP_DigestFinal(hash
, computed_C3
, NULL
)) {
368 SM2err(SM2_F_SM2_DECRYPT
, ERR_R_EVP_LIB
);
372 if (CRYPTO_memcmp(computed_C3
, C3
, hash_size
) != 0) {
373 SM2err(SM2_F_SM2_DECRYPT
, SM2_R_INVALID_DIGEST
);
378 *ptext_len
= msg_len
;
382 memset(ptext_buf
, 0, *ptext_len
);
384 OPENSSL_free(msg_mask
);
386 OPENSSL_free(computed_C3
);
389 SM2_Ciphertext_free(sm2_ctext
);
390 EVP_MD_CTX_free(hash
);