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 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 SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_DIGEST);
81 if (field_size == 0) {
82 SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_FIELD);
86 overhead = 10 + 2 * field_size + (size_t)md_size;
87 if (msg_len <= overhead) {
88 SM2err(SM2_F_SM2_PLAINTEXT_SIZE, 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);
142 /* NULL these before any "goto done" */
143 ctext_struct.C2 = NULL;
144 ctext_struct.C3 = NULL;
146 if (hash == NULL || C3_size <= 0) {
147 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
151 field_size = ec_field_size(group);
152 if (field_size == 0) {
153 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
157 kG = EC_POINT_new(group);
158 kP = EC_POINT_new(group);
160 if (kG == NULL || kP == NULL || ctx == NULL) {
161 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
167 x1 = BN_CTX_get(ctx);
168 x2 = BN_CTX_get(ctx);
169 y1 = BN_CTX_get(ctx);
170 y2 = BN_CTX_get(ctx);
173 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
177 x2y2 = OPENSSL_zalloc(2 * field_size);
178 C3 = OPENSSL_zalloc(C3_size);
180 if (x2y2 == NULL || C3 == NULL) {
181 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
185 memset(ciphertext_buf, 0, *ciphertext_len);
187 if (!BN_priv_rand_range(k, order)) {
188 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
192 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
193 || !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
194 || !EC_POINT_mul(group, kP, NULL, P, k, ctx)
195 || !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
196 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
200 if (BN_bn2binpad(x2, x2y2, field_size) < 0
201 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
202 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
206 msg_mask = OPENSSL_zalloc(msg_len);
207 if (msg_mask == NULL) {
208 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
212 /* X9.63 with no salt happens to match the KDF used in SM2 */
213 if (!ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
215 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
219 for (i = 0; i != msg_len; ++i)
220 msg_mask[i] ^= msg[i];
222 if (EVP_DigestInit(hash, digest) == 0
223 || EVP_DigestUpdate(hash, x2y2, field_size) == 0
224 || EVP_DigestUpdate(hash, msg, msg_len) == 0
225 || EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
226 || EVP_DigestFinal(hash, C3, NULL) == 0) {
227 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
231 ctext_struct.C1x = x1;
232 ctext_struct.C1y = y1;
233 ctext_struct.C3 = ASN1_OCTET_STRING_new();
234 ctext_struct.C2 = ASN1_OCTET_STRING_new();
236 if (ctext_struct.C3 == NULL || ctext_struct.C2 == NULL) {
237 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
240 if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
241 || !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
242 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
246 ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
247 /* Ensure cast to size_t is safe */
248 if (ciphertext_leni < 0) {
249 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
252 *ciphertext_len = (size_t)ciphertext_leni;
257 ASN1_OCTET_STRING_free(ctext_struct.C2);
258 ASN1_OCTET_STRING_free(ctext_struct.C3);
259 OPENSSL_free(msg_mask);
262 EVP_MD_CTX_free(hash);
269 int sm2_decrypt(const EC_KEY *key,
270 const EVP_MD *digest,
271 const uint8_t *ciphertext,
272 size_t ciphertext_len, uint8_t *ptext_buf, size_t *ptext_len)
277 const EC_GROUP *group = EC_KEY_get0_group(key);
279 struct SM2_Ciphertext_st *sm2_ctext = NULL;
282 uint8_t *x2y2 = NULL;
283 uint8_t *computed_C3 = NULL;
284 const size_t field_size = ec_field_size(group);
285 const int hash_size = EVP_MD_size(digest);
286 uint8_t *msg_mask = NULL;
287 const uint8_t *C2 = NULL;
288 const uint8_t *C3 = NULL;
290 EVP_MD_CTX *hash = NULL;
292 if (field_size == 0 || hash_size <= 0)
295 memset(ptext_buf, 0xFF, *ptext_len);
297 sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
299 if (sm2_ctext == NULL) {
300 SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
304 if (sm2_ctext->C3->length != hash_size) {
305 SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
309 C2 = sm2_ctext->C2->data;
310 C3 = sm2_ctext->C3->data;
311 msg_len = sm2_ctext->C2->length;
315 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
320 x2 = BN_CTX_get(ctx);
321 y2 = BN_CTX_get(ctx);
324 SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
328 msg_mask = OPENSSL_zalloc(msg_len);
329 x2y2 = OPENSSL_zalloc(2 * field_size);
330 computed_C3 = OPENSSL_zalloc(hash_size);
332 if (msg_mask == NULL || x2y2 == NULL || computed_C3 == NULL) {
333 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
337 C1 = EC_POINT_new(group);
339 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
343 if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
345 || !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
347 || !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
348 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
352 if (BN_bn2binpad(x2, x2y2, field_size) < 0
353 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
354 || !ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
356 SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
360 for (i = 0; i != msg_len; ++i)
361 ptext_buf[i] = C2[i] ^ msg_mask[i];
363 hash = EVP_MD_CTX_new();
365 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
369 if (!EVP_DigestInit(hash, digest)
370 || !EVP_DigestUpdate(hash, x2y2, field_size)
371 || !EVP_DigestUpdate(hash, ptext_buf, msg_len)
372 || !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
373 || !EVP_DigestFinal(hash, computed_C3, NULL)) {
374 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
378 if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
379 SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
384 *ptext_len = msg_len;
388 memset(ptext_buf, 0, *ptext_len);
390 OPENSSL_free(msg_mask);
392 OPENSSL_free(computed_C3);
395 SM2_Ciphertext_free(sm2_ctext);
396 EVP_MD_CTX_free(hash);