2 * Copyright 2017-2024 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" /* ossl_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 const BIGNUM *p = EC_GROUP_get0_field(group);
54 return BN_num_bytes(p);
57 int ossl_sm2_plaintext_size(const unsigned char *ct, size_t ct_size,
60 struct SM2_Ciphertext_st *sm2_ctext = NULL;
62 sm2_ctext = d2i_SM2_Ciphertext(NULL, &ct, ct_size);
64 if (sm2_ctext == NULL) {
65 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
69 *pt_size = sm2_ctext->C2->length;
70 SM2_Ciphertext_free(sm2_ctext);
75 int ossl_sm2_ciphertext_size(const EC_KEY *key, const EVP_MD *digest,
76 size_t msg_len, size_t *ct_size)
78 const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
79 const int md_size = EVP_MD_get_size(digest);
82 if (field_size == 0 || md_size < 0)
85 /* Integer and string are simple type; set constructed = 0, means primitive and definite length encoding. */
86 sz = 2 * ASN1_object_size(0, field_size + 1, V_ASN1_INTEGER)
87 + ASN1_object_size(0, md_size, V_ASN1_OCTET_STRING)
88 + ASN1_object_size(0, msg_len, V_ASN1_OCTET_STRING);
89 /* Sequence is structured type; set constructed = 1, means constructed and definite length encoding. */
90 *ct_size = ASN1_object_size(1, sz, V_ASN1_SEQUENCE);
95 int ossl_sm2_encrypt(const EC_KEY *key,
97 const uint8_t *msg, size_t msg_len,
98 uint8_t *ciphertext_buf, size_t *ciphertext_len)
100 int rc = 0, ciphertext_leni;
108 EVP_MD_CTX *hash = EVP_MD_CTX_new();
109 struct SM2_Ciphertext_st ctext_struct;
110 const EC_GROUP *group = EC_KEY_get0_group(key);
111 const BIGNUM *order = EC_GROUP_get0_order(group);
112 const EC_POINT *P = EC_KEY_get0_public_key(key);
115 uint8_t *msg_mask = NULL;
116 uint8_t *x2y2 = NULL;
119 const int C3_size = EVP_MD_get_size(digest);
120 EVP_MD *fetched_digest = NULL;
121 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
122 const char *propq = ossl_ec_key_get0_propq(key);
124 /* NULL these before any "goto done" */
125 ctext_struct.C2 = NULL;
126 ctext_struct.C3 = NULL;
128 if (hash == NULL || C3_size <= 0) {
129 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
133 field_size = ec_field_size(group);
134 if (field_size == 0) {
135 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
139 kG = EC_POINT_new(group);
140 kP = EC_POINT_new(group);
141 if (kG == NULL || kP == NULL) {
142 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
145 ctx = BN_CTX_new_ex(libctx);
147 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
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 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
163 x2y2 = OPENSSL_zalloc(2 * field_size);
164 C3 = OPENSSL_zalloc(C3_size);
166 if (x2y2 == NULL || C3 == NULL)
169 memset(ciphertext_buf, 0, *ciphertext_len);
171 if (!BN_priv_rand_range_ex(k, order, 0, ctx)) {
172 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
176 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
177 || !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
178 || !EC_POINT_mul(group, kP, NULL, P, k, ctx)
179 || !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
180 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
184 if (BN_bn2binpad(x2, x2y2, field_size) < 0
185 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
186 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
190 msg_mask = OPENSSL_zalloc(msg_len);
191 if (msg_mask == NULL)
194 /* X9.63 with no salt happens to match the KDF used in SM2 */
195 if (!ossl_ecdh_kdf_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
196 digest, libctx, propq)) {
197 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
201 for (i = 0; i != msg_len; ++i)
202 msg_mask[i] ^= msg[i];
204 fetched_digest = EVP_MD_fetch(libctx, EVP_MD_get0_name(digest), propq);
205 if (fetched_digest == NULL) {
206 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
209 if (EVP_DigestInit(hash, fetched_digest) == 0
210 || EVP_DigestUpdate(hash, x2y2, field_size) == 0
211 || EVP_DigestUpdate(hash, msg, msg_len) == 0
212 || EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
213 || EVP_DigestFinal(hash, C3, NULL) == 0) {
214 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
218 ctext_struct.C1x = x1;
219 ctext_struct.C1y = y1;
220 ctext_struct.C3 = ASN1_OCTET_STRING_new();
221 ctext_struct.C2 = ASN1_OCTET_STRING_new();
223 if (ctext_struct.C3 == NULL || ctext_struct.C2 == NULL) {
224 ERR_raise(ERR_LIB_SM2, ERR_R_ASN1_LIB);
227 if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
228 || !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
229 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
233 ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
234 /* Ensure cast to size_t is safe */
235 if (ciphertext_leni < 0) {
236 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
239 *ciphertext_len = (size_t)ciphertext_leni;
244 EVP_MD_free(fetched_digest);
245 ASN1_OCTET_STRING_free(ctext_struct.C2);
246 ASN1_OCTET_STRING_free(ctext_struct.C3);
247 OPENSSL_free(msg_mask);
250 EVP_MD_CTX_free(hash);
257 int ossl_sm2_decrypt(const EC_KEY *key,
258 const EVP_MD *digest,
259 const uint8_t *ciphertext, size_t ciphertext_len,
260 uint8_t *ptext_buf, size_t *ptext_len)
265 const EC_GROUP *group = EC_KEY_get0_group(key);
267 struct SM2_Ciphertext_st *sm2_ctext = NULL;
270 uint8_t *x2y2 = NULL;
271 uint8_t *computed_C3 = NULL;
272 const size_t field_size = ec_field_size(group);
273 const int hash_size = EVP_MD_get_size(digest);
274 uint8_t *msg_mask = NULL;
275 const uint8_t *C2 = NULL;
276 const uint8_t *C3 = NULL;
278 EVP_MD_CTX *hash = NULL;
279 OSSL_LIB_CTX *libctx = ossl_ec_key_get_libctx(key);
280 const char *propq = ossl_ec_key_get0_propq(key);
282 if (field_size == 0 || hash_size <= 0)
285 memset(ptext_buf, 0xFF, *ptext_len);
287 sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
289 if (sm2_ctext == NULL) {
290 ERR_raise(ERR_LIB_SM2, SM2_R_ASN1_ERROR);
294 if (sm2_ctext->C3->length != hash_size) {
295 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_ENCODING);
299 C2 = sm2_ctext->C2->data;
300 C3 = sm2_ctext->C3->data;
301 msg_len = sm2_ctext->C2->length;
302 if (*ptext_len < (size_t)msg_len) {
303 ERR_raise(ERR_LIB_SM2, SM2_R_BUFFER_TOO_SMALL);
307 ctx = BN_CTX_new_ex(libctx);
309 ERR_raise(ERR_LIB_SM2, ERR_R_BN_LIB);
314 x2 = BN_CTX_get(ctx);
315 y2 = BN_CTX_get(ctx);
318 ERR_raise(ERR_LIB_SM2, 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)
329 C1 = EC_POINT_new(group);
331 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
335 if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
337 || !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
339 || !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
340 ERR_raise(ERR_LIB_SM2, ERR_R_EC_LIB);
344 if (BN_bn2binpad(x2, x2y2, field_size) < 0
345 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
346 || !ossl_ecdh_kdf_X9_63(msg_mask, msg_len, x2y2, 2 * field_size,
347 NULL, 0, digest, libctx, propq)) {
348 ERR_raise(ERR_LIB_SM2, ERR_R_INTERNAL_ERROR);
352 for (i = 0; i != msg_len; ++i)
353 ptext_buf[i] = C2[i] ^ msg_mask[i];
355 hash = EVP_MD_CTX_new();
357 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
361 if (!EVP_DigestInit(hash, digest)
362 || !EVP_DigestUpdate(hash, x2y2, field_size)
363 || !EVP_DigestUpdate(hash, ptext_buf, msg_len)
364 || !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
365 || !EVP_DigestFinal(hash, computed_C3, NULL)) {
366 ERR_raise(ERR_LIB_SM2, ERR_R_EVP_LIB);
370 if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
371 ERR_raise(ERR_LIB_SM2, SM2_R_INVALID_DIGEST);
376 *ptext_len = msg_len;
380 memset(ptext_buf, 0, *ptext_len);
382 OPENSSL_free(msg_mask);
384 OPENSSL_free(computed_C3);
387 SM2_Ciphertext_free(sm2_ctext);
388 EVP_MD_CTX_free(hash);