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);