2 * Copyright 2017-2020 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);
141 EVP_MD *fetched_digest = NULL;
142 OPENSSL_CTX *libctx = ec_key_get_libctx(key);
143 const char *propq = ec_key_get0_propq(key);
145 /* NULL these before any "goto done" */
146 ctext_struct.C2 = NULL;
147 ctext_struct.C3 = NULL;
149 if (hash == NULL || C3_size <= 0) {
150 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
154 field_size = ec_field_size(group);
155 if (field_size == 0) {
156 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
160 kG = EC_POINT_new(group);
161 kP = EC_POINT_new(group);
162 ctx = BN_CTX_new_ex(libctx);
163 if (kG == NULL || kP == NULL || ctx == NULL) {
164 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
170 x1 = BN_CTX_get(ctx);
171 x2 = BN_CTX_get(ctx);
172 y1 = BN_CTX_get(ctx);
173 y2 = BN_CTX_get(ctx);
176 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
180 x2y2 = OPENSSL_zalloc(2 * field_size);
181 C3 = OPENSSL_zalloc(C3_size);
183 if (x2y2 == NULL || C3 == NULL) {
184 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
188 memset(ciphertext_buf, 0, *ciphertext_len);
190 if (!BN_priv_rand_range(k, order)) {
191 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
195 if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
196 || !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
197 || !EC_POINT_mul(group, kP, NULL, P, k, ctx)
198 || !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
199 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
203 if (BN_bn2binpad(x2, x2y2, field_size) < 0
204 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
205 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
209 msg_mask = OPENSSL_zalloc(msg_len);
210 if (msg_mask == NULL) {
211 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
215 /* X9.63 with no salt happens to match the KDF used in SM2 */
216 if (!ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
217 digest, libctx, propq)) {
218 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
222 for (i = 0; i != msg_len; ++i)
223 msg_mask[i] ^= msg[i];
225 fetched_digest = EVP_MD_fetch(libctx, EVP_MD_name(digest), propq);
226 if (fetched_digest == NULL) {
227 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
230 if (EVP_DigestInit(hash, fetched_digest) == 0
231 || EVP_DigestUpdate(hash, x2y2, field_size) == 0
232 || EVP_DigestUpdate(hash, msg, msg_len) == 0
233 || EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
234 || EVP_DigestFinal(hash, C3, NULL) == 0) {
235 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
239 ctext_struct.C1x = x1;
240 ctext_struct.C1y = y1;
241 ctext_struct.C3 = ASN1_OCTET_STRING_new();
242 ctext_struct.C2 = ASN1_OCTET_STRING_new();
244 if (ctext_struct.C3 == NULL || ctext_struct.C2 == NULL) {
245 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
248 if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
249 || !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
250 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
254 ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
255 /* Ensure cast to size_t is safe */
256 if (ciphertext_leni < 0) {
257 SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
260 *ciphertext_len = (size_t)ciphertext_leni;
265 EVP_MD_free(fetched_digest);
266 ASN1_OCTET_STRING_free(ctext_struct.C2);
267 ASN1_OCTET_STRING_free(ctext_struct.C3);
268 OPENSSL_free(msg_mask);
271 EVP_MD_CTX_free(hash);
278 int sm2_decrypt(const EC_KEY *key,
279 const EVP_MD *digest,
280 const uint8_t *ciphertext,
281 size_t ciphertext_len, uint8_t *ptext_buf, size_t *ptext_len)
286 const EC_GROUP *group = EC_KEY_get0_group(key);
288 struct SM2_Ciphertext_st *sm2_ctext = NULL;
291 uint8_t *x2y2 = NULL;
292 uint8_t *computed_C3 = NULL;
293 const size_t field_size = ec_field_size(group);
294 const int hash_size = EVP_MD_size(digest);
295 uint8_t *msg_mask = NULL;
296 const uint8_t *C2 = NULL;
297 const uint8_t *C3 = NULL;
299 EVP_MD_CTX *hash = NULL;
300 OPENSSL_CTX *libctx = ec_key_get_libctx(key);
301 const char *propq = ec_key_get0_propq(key);
303 if (field_size == 0 || hash_size <= 0)
306 memset(ptext_buf, 0xFF, *ptext_len);
308 sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
310 if (sm2_ctext == NULL) {
311 SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
315 if (sm2_ctext->C3->length != hash_size) {
316 SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
320 C2 = sm2_ctext->C2->data;
321 C3 = sm2_ctext->C3->data;
322 msg_len = sm2_ctext->C2->length;
324 ctx = BN_CTX_new_ex(libctx);
326 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
331 x2 = BN_CTX_get(ctx);
332 y2 = BN_CTX_get(ctx);
335 SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
339 msg_mask = OPENSSL_zalloc(msg_len);
340 x2y2 = OPENSSL_zalloc(2 * field_size);
341 computed_C3 = OPENSSL_zalloc(hash_size);
343 if (msg_mask == NULL || x2y2 == NULL || computed_C3 == NULL) {
344 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
348 C1 = EC_POINT_new(group);
350 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
354 if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
356 || !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
358 || !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
359 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
363 if (BN_bn2binpad(x2, x2y2, field_size) < 0
364 || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
365 || !ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
366 digest, libctx, propq)) {
367 SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
371 for (i = 0; i != msg_len; ++i)
372 ptext_buf[i] = C2[i] ^ msg_mask[i];
374 hash = EVP_MD_CTX_new();
376 SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
380 if (!EVP_DigestInit(hash, digest)
381 || !EVP_DigestUpdate(hash, x2y2, field_size)
382 || !EVP_DigestUpdate(hash, ptext_buf, msg_len)
383 || !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
384 || !EVP_DigestFinal(hash, computed_C3, NULL)) {
385 SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
389 if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
390 SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
395 *ptext_len = msg_len;
399 memset(ptext_buf, 0, *ptext_len);
401 OPENSSL_free(msg_mask);
403 OPENSSL_free(computed_C3);
406 SM2_Ciphertext_free(sm2_ctext);
407 EVP_MD_CTX_free(hash);