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 EC_GROUP_get_curve_GFp(group, p, a, b, NULL);
52 field_size = (BN_num_bits(p) + 7) / 8;
62 size_t SM2_plaintext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len)
64 const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
65 const size_t md_size = EVP_MD_size(digest);
67 const size_t overhead = 10 + 2 * field_size + md_size;
68 if(msg_len <= overhead)
71 return msg_len - overhead;
74 size_t SM2_ciphertext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len)
76 const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
77 const size_t md_size = EVP_MD_size(digest);
78 return 10 + 2 * field_size + md_size + msg_len;
81 int SM2_encrypt(const EC_KEY *key,
84 size_t msg_len, uint8_t *ciphertext_buf, size_t *ciphertext_len)
95 EVP_MD_CTX *hash = EVP_MD_CTX_new();
97 struct SM2_Ciphertext_st ctext_struct;
98 const EC_GROUP *group = EC_KEY_get0_group(key);
99 const BIGNUM *order = EC_GROUP_get0_order(group);
100 const EC_POINT *P = EC_KEY_get0_public_key(key);
103 uint8_t *msg_mask = NULL;
105 uint8_t *x2y2 = NULL;
108 const size_t field_size = EC_field_size(group);
109 const size_t C3_size = EVP_MD_size(digest);
111 if (field_size == 0 || C3_size == 0)
114 kG = EC_POINT_new(group);
115 kP = EC_POINT_new(group);
116 if (kG == NULL || kP == NULL)
118 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
125 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
131 x1 = BN_CTX_get(ctx);
132 x2 = BN_CTX_get(ctx);
133 y1 = BN_CTX_get(ctx);
134 y2 = BN_CTX_get(ctx);
138 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
142 x2y2 = OPENSSL_zalloc(2 * field_size);
143 C3 = OPENSSL_zalloc(C3_size);
145 if (x2y2 == NULL || C3 == NULL)
147 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
151 memset(ciphertext_buf, 0, *ciphertext_len);
153 BN_priv_rand_range(k, order);
155 if (EC_POINT_mul(group, kG, k, NULL, NULL, ctx) == 0)
157 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
161 if (EC_POINT_get_affine_coordinates_GFp(group, kG, x1, y1, ctx) == 0)
163 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
167 if (EC_POINT_mul(group, kP, NULL, P, k, ctx) == 0)
169 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
173 if (EC_POINT_get_affine_coordinates_GFp(group, kP, x2, y2, ctx) == 0)
175 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
179 BN_bn2binpad(x2, x2y2, field_size);
180 BN_bn2binpad(y2, x2y2 + field_size, field_size);
182 msg_mask = OPENSSL_zalloc(msg_len);
183 if (msg_mask == NULL)
185 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
189 /* X9.63 with no salt happens to match the KDF used in SM2 */
190 if (ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0, digest)
194 for (i = 0; i != msg_len; ++i)
195 msg_mask[i] ^= msg[i];
197 if (EVP_DigestInit(hash, digest) == 0)
199 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
203 if (EVP_DigestUpdate(hash, x2y2, field_size) == 0)
205 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
209 if (EVP_DigestUpdate(hash, msg, msg_len) == 0)
211 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
215 if (EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0)
217 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
221 if (EVP_DigestFinal(hash, C3, NULL) == 0)
223 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
227 ctext_struct.C1x = x1;
228 ctext_struct.C1y = y1;
229 ctext_struct.C3 = ASN1_OCTET_STRING_new();
230 ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size);
231 ctext_struct.C2 = ASN1_OCTET_STRING_new();
232 ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len);
234 *ciphertext_len = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
236 ASN1_OCTET_STRING_free(ctext_struct.C2);
237 ASN1_OCTET_STRING_free(ctext_struct.C3);
242 OPENSSL_free(msg_mask);
245 EVP_MD_CTX_free(hash);
252 int SM2_decrypt(const EC_KEY *key,
253 const EVP_MD *digest,
254 const uint8_t *ciphertext,
255 size_t ciphertext_len, uint8_t *ptext_buf, size_t *ptext_len)
261 const EC_GROUP *group = EC_KEY_get0_group(key);
263 struct SM2_Ciphertext_st *sm2_ctext = NULL;
267 uint8_t *x2y2 = NULL;
268 uint8_t *computed_C3 = NULL;
270 const size_t field_size = EC_field_size(group);
271 const int hash_size = EVP_MD_size(digest);
273 uint8_t *msg_mask = NULL;
274 const uint8_t *C2 = NULL;
275 const uint8_t *C3 = NULL;
277 EVP_MD_CTX *hash = NULL;
279 if (field_size == 0 || hash_size == 0)
282 memset(ptext_buf, 0xFF, *ptext_len);
284 sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
286 if (sm2_ctext == NULL)
288 SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
292 if (sm2_ctext->C3->length != hash_size)
294 SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
298 C2 = sm2_ctext->C2->data;
299 C3 = sm2_ctext->C3->data;
300 msg_len = sm2_ctext->C2->length;
305 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
310 x2 = BN_CTX_get(ctx);
311 y2 = BN_CTX_get(ctx);
315 SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
319 msg_mask = OPENSSL_zalloc(msg_len);
320 x2y2 = OPENSSL_zalloc(2 * field_size);
321 computed_C3 = OPENSSL_zalloc(hash_size);
323 if(msg_mask == NULL || x2y2 == NULL || computed_C3 == NULL)
325 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
329 C1 = EC_POINT_new(group);
332 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
336 if (EC_POINT_set_affine_coordinates_GFp
337 (group, C1, sm2_ctext->C1x, sm2_ctext->C1y, ctx) == 0)
339 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
343 if (EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key), ctx) ==
346 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
350 if (EC_POINT_get_affine_coordinates_GFp(group, C1, x2, y2, ctx) == 0)
352 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
356 BN_bn2binpad(x2, x2y2, field_size);
357 BN_bn2binpad(y2, x2y2 + field_size, field_size);
359 if (ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0, digest)
363 for (i = 0; i != msg_len; ++i)
364 ptext_buf[i] = C2[i] ^ msg_mask[i];
366 hash = EVP_MD_CTX_new();
370 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
374 if (EVP_DigestInit(hash, digest) == 0)
376 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
380 if (EVP_DigestUpdate(hash, x2y2, field_size) == 0)
382 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
386 if (EVP_DigestUpdate(hash, ptext_buf, msg_len) == 0)
388 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
392 if (EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0)
394 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
398 if (EVP_DigestFinal(hash, computed_C3, NULL) == 0)
400 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
404 if (memcmp(computed_C3, C3, hash_size) != 0)
408 *ptext_len = msg_len;
413 memset(ptext_buf, 0, *ptext_len);
415 OPENSSL_free(msg_mask);
417 OPENSSL_free(computed_C3);
420 SM2_Ciphertext_free(sm2_ctext);
421 EVP_MD_CTX_free(hash);