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 <openssl/err.h>
15 #include <openssl/evp.h>
16 #include <openssl/bn.h>
17 #include <openssl/asn1.h>
18 #include <openssl/asn1t.h>
21 typedef struct SM2_Ciphertext_st SM2_Ciphertext;
22 DECLARE_ASN1_FUNCTIONS(SM2_Ciphertext)
24 struct SM2_Ciphertext_st {
27 ASN1_OCTET_STRING *C3;
28 ASN1_OCTET_STRING *C2;
31 ASN1_SEQUENCE(SM2_Ciphertext) = {
32 ASN1_SIMPLE(SM2_Ciphertext, C1x, BIGNUM),
33 ASN1_SIMPLE(SM2_Ciphertext, C1y, BIGNUM),
34 ASN1_SIMPLE(SM2_Ciphertext, C3, ASN1_OCTET_STRING),
35 ASN1_SIMPLE(SM2_Ciphertext, C2, ASN1_OCTET_STRING),
36 } ASN1_SEQUENCE_END(SM2_Ciphertext)
38 IMPLEMENT_ASN1_FUNCTIONS(SM2_Ciphertext)
40 static size_t ec_field_size(const EC_GROUP *group)
42 /* Is there some simpler way to do this? */
46 size_t field_size = 0;
48 if (p == NULL || a == NULL || b == NULL)
51 if (!EC_GROUP_get_curve(group, p, a, b, NULL))
53 field_size = (BN_num_bits(p) + 7) / 8;
63 int sm2_plaintext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len,
66 const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
67 const int md_size = EVP_MD_size(digest);
71 SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_DIGEST);
74 if (field_size == 0) {
75 SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_FIELD);
79 overhead = 10 + 2 * field_size + (size_t)md_size;
80 if (msg_len <= overhead) {
81 SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
85 *pt_size = msg_len - overhead;
89 int sm2_ciphertext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len,
92 const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
93 const int md_size = EVP_MD_size(digest);
95 if (field_size == 0 || md_size < 0)
98 *ct_size = 12 + 2 * field_size + (size_t)md_size + msg_len;
102 int sm2_encrypt(const EC_KEY *key,
103 const EVP_MD *digest,
105 size_t msg_len, uint8_t *ciphertext_buf, size_t *ciphertext_len)
107 int rc = 0, ciphertext_leni;
115 EVP_MD_CTX *hash = EVP_MD_CTX_new();
116 struct SM2_Ciphertext_st ctext_struct;
117 const EC_GROUP *group = EC_KEY_get0_group(key);
118 const BIGNUM *order = EC_GROUP_get0_order(group);
119 const EC_POINT *P = EC_KEY_get0_public_key(key);
122 uint8_t *msg_mask = NULL;
123 uint8_t *x2y2 = NULL;
126 const int C3_size = EVP_MD_size(digest);
128 /* NULL these before any "goto done" */
129 ctext_struct.C2 = NULL;
130 ctext_struct.C3 = NULL;
132 if (hash == NULL || C3_size <= 0) {
133 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
137 field_size = ec_field_size(group);
138 if (field_size == 0) {
139 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
143 kG = EC_POINT_new(group);
144 kP = EC_POINT_new(group);
146 if (kG == NULL || kP == NULL || ctx == NULL) {
147 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
153 x1 = BN_CTX_get(ctx);
154 x2 = BN_CTX_get(ctx);
155 y1 = BN_CTX_get(ctx);
156 y2 = BN_CTX_get(ctx);
159 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
163 x2y2 = OPENSSL_zalloc(2 * field_size);
164 C3 = OPENSSL_zalloc(C3_size);
166 if (x2y2 == NULL || C3 == NULL) {
167 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
171 memset(ciphertext_buf, 0, *ciphertext_len);
173 if (!BN_priv_rand_range(k, order)) {
174 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
178 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
179 || !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
180 || !EC_POINT_mul(group, kP, NULL, P, k, ctx)
181 || !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
182 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
186 if (BN_bn2binpad(x2, x2y2, field_size) < 0
187 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
188 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
192 msg_mask = OPENSSL_zalloc(msg_len);
193 if (msg_mask == NULL) {
194 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
198 /* X9.63 with no salt happens to match the KDF used in SM2 */
199 if (!ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
201 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
205 for (i = 0; i != msg_len; ++i)
206 msg_mask[i] ^= msg[i];
208 if (EVP_DigestInit(hash, digest) == 0
209 || EVP_DigestUpdate(hash, x2y2, field_size) == 0
210 || EVP_DigestUpdate(hash, msg, msg_len) == 0
211 || EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
212 || EVP_DigestFinal(hash, C3, NULL) == 0) {
213 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
217 ctext_struct.C1x = x1;
218 ctext_struct.C1y = y1;
219 ctext_struct.C3 = ASN1_OCTET_STRING_new();
220 ctext_struct.C2 = ASN1_OCTET_STRING_new();
222 if (ctext_struct.C3 == NULL || ctext_struct.C2 == NULL) {
223 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
226 if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
227 || !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
228 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
232 ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
233 /* Ensure cast to size_t is safe */
234 if (ciphertext_leni < 0) {
235 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
238 *ciphertext_len = (size_t)ciphertext_leni;
243 ASN1_OCTET_STRING_free(ctext_struct.C2);
244 ASN1_OCTET_STRING_free(ctext_struct.C3);
245 OPENSSL_free(msg_mask);
248 EVP_MD_CTX_free(hash);
255 int sm2_decrypt(const EC_KEY *key,
256 const EVP_MD *digest,
257 const uint8_t *ciphertext,
258 size_t ciphertext_len, uint8_t *ptext_buf, size_t *ptext_len)
263 const EC_GROUP *group = EC_KEY_get0_group(key);
265 struct SM2_Ciphertext_st *sm2_ctext = NULL;
268 uint8_t *x2y2 = NULL;
269 uint8_t *computed_C3 = NULL;
270 const size_t field_size = ec_field_size(group);
271 const int hash_size = EVP_MD_size(digest);
272 uint8_t *msg_mask = NULL;
273 const uint8_t *C2 = NULL;
274 const uint8_t *C3 = NULL;
276 EVP_MD_CTX *hash = NULL;
278 if (field_size == 0 || hash_size <= 0)
281 memset(ptext_buf, 0xFF, *ptext_len);
283 sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
285 if (sm2_ctext == NULL) {
286 SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
290 if (sm2_ctext->C3->length != hash_size) {
291 SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
295 C2 = sm2_ctext->C2->data;
296 C3 = sm2_ctext->C3->data;
297 msg_len = sm2_ctext->C2->length;
301 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
306 x2 = BN_CTX_get(ctx);
307 y2 = BN_CTX_get(ctx);
310 SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
314 msg_mask = OPENSSL_zalloc(msg_len);
315 x2y2 = OPENSSL_zalloc(2 * field_size);
316 computed_C3 = OPENSSL_zalloc(hash_size);
318 if (msg_mask == NULL || x2y2 == NULL || computed_C3 == NULL) {
319 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
323 C1 = EC_POINT_new(group);
325 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
329 if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
331 || !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
333 || !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
334 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
338 if (BN_bn2binpad(x2, x2y2, field_size) < 0
339 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
340 || !ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
342 SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
346 for (i = 0; i != msg_len; ++i)
347 ptext_buf[i] = C2[i] ^ msg_mask[i];
349 hash = EVP_MD_CTX_new();
351 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
355 if (!EVP_DigestInit(hash, digest)
356 || !EVP_DigestUpdate(hash, x2y2, field_size)
357 || !EVP_DigestUpdate(hash, ptext_buf, msg_len)
358 || !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
359 || !EVP_DigestFinal(hash, computed_C3, NULL)) {
360 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
364 if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
365 SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
370 *ptext_len = msg_len;
374 memset(ptext_buf, 0, *ptext_len);
376 OPENSSL_free(msg_mask);
378 OPENSSL_free(computed_C3);
381 SM2_Ciphertext_free(sm2_ctext);
382 EVP_MD_CTX_free(hash);