/src/openssl111/crypto/sm2/sm2_crypt.c

Source (jump to first uncovered line)
/*
 * Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.
 * Copyright 2017 Ribose Inc. All Rights Reserved.
 * Ported from Ribose contributions from Botan.
 *
 * Licensed under the OpenSSL license (the "License").  You may not use
 * this file except in compliance with the License.  You can obtain a copy
 * in the file LICENSE in the source distribution or at
 * https://www.openssl.org/source/license.html
 */

#include "crypto/sm2.h"
#include "crypto/sm2err.h"
#include "crypto/ec.h" /* ecdh_KDF_X9_63() */
#include <openssl/err.h>
#include <openssl/evp.h>
#include <openssl/bn.h>
#include <openssl/asn1.h>
#include <openssl/asn1t.h>
#include <string.h>

typedef struct SM2_Ciphertext_st SM2_Ciphertext;
DECLARE_ASN1_FUNCTIONS(SM2_Ciphertext)

struct SM2_Ciphertext_st {
    BIGNUM *C1x;
    BIGNUM *C1y;
    ASN1_OCTET_STRING *C3;
    ASN1_OCTET_STRING *C2;
};

ASN1_SEQUENCE(SM2_Ciphertext) = {
    ASN1_SIMPLE(SM2_Ciphertext, C1x, BIGNUM),
    ASN1_SIMPLE(SM2_Ciphertext, C1y, BIGNUM),
    ASN1_SIMPLE(SM2_Ciphertext, C3, ASN1_OCTET_STRING),
    ASN1_SIMPLE(SM2_Ciphertext, C2, ASN1_OCTET_STRING),
} ASN1_SEQUENCE_END(SM2_Ciphertext)

IMPLEMENT_ASN1_FUNCTIONS(SM2_Ciphertext)

static size_t ec_field_size(const EC_GROUP *group)
{
    /* Is there some simpler way to do this? */
    BIGNUM *p = BN_new();
    BIGNUM *a = BN_new();
    BIGNUM *b = BN_new();
    size_t field_size = 0;

    if (p == NULL || a == NULL || b == NULL)
       goto done;

    if (!EC_GROUP_get_curve(group, p, a, b, NULL))
        goto done;
    field_size = (BN_num_bits(p) + 7) / 8;

 done:
    BN_free(p);
    BN_free(a);
    BN_free(b);

    return field_size;
}

int sm2_plaintext_size(const unsigned char *ct, size_t ct_size, size_t *pt_size)
{
    struct SM2_Ciphertext_st *sm2_ctext = NULL;

    sm2_ctext = d2i_SM2_Ciphertext(NULL, &ct, ct_size);

    if (sm2_ctext == NULL) {
        SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
        return 0;
    }

    *pt_size = sm2_ctext->C2->length;
    SM2_Ciphertext_free(sm2_ctext);

    return 1;
}

int sm2_ciphertext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len,
                        size_t *ct_size)
{
    const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
    const int md_size = EVP_MD_size(digest);
    size_t sz;

    if (field_size == 0 || md_size < 0)
        return 0;

    /* Integer and string are simple type; set constructed = 0, means primitive and definite length encoding. */
    sz = 2 * ASN1_object_size(0, field_size + 1, V_ASN1_INTEGER)
         + ASN1_object_size(0, md_size, V_ASN1_OCTET_STRING)
         + ASN1_object_size(0, msg_len, V_ASN1_OCTET_STRING);
    /* Sequence is structured type; set constructed = 1, means constructed and definite length encoding. */
    *ct_size = ASN1_object_size(1, sz, V_ASN1_SEQUENCE);

    return 1;
}

int sm2_encrypt(const EC_KEY *key,
                const EVP_MD *digest,
                const uint8_t *msg,
                size_t msg_len, uint8_t *ciphertext_buf, size_t *ciphertext_len)
{
    int rc = 0, ciphertext_leni;
    size_t i;
    BN_CTX *ctx = NULL;
    BIGNUM *k = NULL;
    BIGNUM *x1 = NULL;
    BIGNUM *y1 = NULL;
    BIGNUM *x2 = NULL;
    BIGNUM *y2 = NULL;
    EVP_MD_CTX *hash = EVP_MD_CTX_new();
    struct SM2_Ciphertext_st ctext_struct;
    const EC_GROUP *group = EC_KEY_get0_group(key);
    const BIGNUM *order = EC_GROUP_get0_order(group);
    const EC_POINT *P = EC_KEY_get0_public_key(key);
    EC_POINT *kG = NULL;
    EC_POINT *kP = NULL;
    uint8_t *msg_mask = NULL;
    uint8_t *x2y2 = NULL;
    uint8_t *C3 = NULL;
    size_t field_size;
    const int C3_size = EVP_MD_size(digest);

    /* NULL these before any "goto done" */
    ctext_struct.C2 = NULL;
    ctext_struct.C3 = NULL;

    if (hash == NULL || C3_size <= 0) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    field_size = ec_field_size(group);
    if (field_size == 0) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    kG = EC_POINT_new(group);
    kP = EC_POINT_new(group);
    ctx = BN_CTX_new();
    if (kG == NULL || kP == NULL || ctx == NULL) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
        goto done;
    }

    BN_CTX_start(ctx);
    k = BN_CTX_get(ctx);
    x1 = BN_CTX_get(ctx);
    x2 = BN_CTX_get(ctx);
    y1 = BN_CTX_get(ctx);
    y2 = BN_CTX_get(ctx);

    if (y2 == NULL) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
        goto done;
    }

    x2y2 = OPENSSL_zalloc(2 * field_size);
    C3 = OPENSSL_zalloc(C3_size);

    if (x2y2 == NULL || C3 == NULL) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
        goto done;
    }

    memset(ciphertext_buf, 0, *ciphertext_len);

    if (!BN_priv_rand_range(k, order)) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
            || !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
            || !EC_POINT_mul(group, kP, NULL, P, k, ctx)
            || !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
        goto done;
    }

    if (BN_bn2binpad(x2, x2y2, field_size) < 0
            || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    msg_mask = OPENSSL_zalloc(msg_len);
    if (msg_mask == NULL) {
       SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
       goto done;
   }

    /* X9.63 with no salt happens to match the KDF used in SM2 */
    if (!ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
                        digest)) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
        goto done;
    }

    for (i = 0; i != msg_len; ++i)
        msg_mask[i] ^= msg[i];

    if (EVP_DigestInit(hash, digest) == 0
            || EVP_DigestUpdate(hash, x2y2, field_size) == 0
            || EVP_DigestUpdate(hash, msg, msg_len) == 0
            || EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
            || EVP_DigestFinal(hash, C3, NULL) == 0) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
        goto done;
    }

    ctext_struct.C1x = x1;
    ctext_struct.C1y = y1;
    ctext_struct.C3 = ASN1_OCTET_STRING_new();
    ctext_struct.C2 = ASN1_OCTET_STRING_new();

    if (ctext_struct.C3 == NULL || ctext_struct.C2 == NULL) {
       SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
       goto done;
    }
    if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
            || !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
    /* Ensure cast to size_t is safe */
    if (ciphertext_leni < 0) {
        SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
        goto done;
    }
    *ciphertext_len = (size_t)ciphertext_leni;

    rc = 1;

 done:
    ASN1_OCTET_STRING_free(ctext_struct.C2);
    ASN1_OCTET_STRING_free(ctext_struct.C3);
    OPENSSL_free(msg_mask);
    OPENSSL_free(x2y2);
    OPENSSL_free(C3);
    EVP_MD_CTX_free(hash);
    BN_CTX_free(ctx);
    EC_POINT_free(kG);
    EC_POINT_free(kP);
    return rc;
}

int sm2_decrypt(const EC_KEY *key,
                const EVP_MD *digest,
                const uint8_t *ciphertext,
                size_t ciphertext_len, uint8_t *ptext_buf, size_t *ptext_len)
{
    int rc = 0;
    int i;
    BN_CTX *ctx = NULL;
    const EC_GROUP *group = EC_KEY_get0_group(key);
    EC_POINT *C1 = NULL;
    struct SM2_Ciphertext_st *sm2_ctext = NULL;
    BIGNUM *x2 = NULL;
    BIGNUM *y2 = NULL;
    uint8_t *x2y2 = NULL;
    uint8_t *computed_C3 = NULL;
    const size_t field_size = ec_field_size(group);
    const int hash_size = EVP_MD_size(digest);
    uint8_t *msg_mask = NULL;
    const uint8_t *C2 = NULL;
    const uint8_t *C3 = NULL;
    int msg_len = 0;
    EVP_MD_CTX *hash = NULL;

    if (field_size == 0 || hash_size <= 0)
       goto done;

    memset(ptext_buf, 0xFF, *ptext_len);

    sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);

    if (sm2_ctext == NULL) {
        SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
        goto done;
    }

    if (sm2_ctext->C3->length != hash_size) {
        SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
        goto done;
    }

    C2 = sm2_ctext->C2->data;
    C3 = sm2_ctext->C3->data;
    msg_len = sm2_ctext->C2->length;
    if (*ptext_len < (size_t)msg_len) {
        SM2err(SM2_F_SM2_DECRYPT, SM2_R_BUFFER_TOO_SMALL);
        goto done;
    }

    ctx = BN_CTX_new();
    if (ctx == NULL) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
        goto done;
    }

    BN_CTX_start(ctx);
    x2 = BN_CTX_get(ctx);
    y2 = BN_CTX_get(ctx);

    if (y2 == NULL) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
        goto done;
    }

    msg_mask = OPENSSL_zalloc(msg_len);
    x2y2 = OPENSSL_zalloc(2 * field_size);
    computed_C3 = OPENSSL_zalloc(hash_size);

    if (msg_mask == NULL || x2y2 == NULL || computed_C3 == NULL) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
        goto done;
    }

    C1 = EC_POINT_new(group);
    if (C1 == NULL) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
        goto done;
    }

    if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
                                         sm2_ctext->C1y, ctx)
            || !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
                             ctx)
            || !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
        goto done;
    }

    if (BN_bn2binpad(x2, x2y2, field_size) < 0
            || BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
            || !ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
                               digest)) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
        goto done;
    }

    for (i = 0; i != msg_len; ++i)
        ptext_buf[i] = C2[i] ^ msg_mask[i];

    hash = EVP_MD_CTX_new();
    if (hash == NULL) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
        goto done;
    }

    if (!EVP_DigestInit(hash, digest)
            || !EVP_DigestUpdate(hash, x2y2, field_size)
            || !EVP_DigestUpdate(hash, ptext_buf, msg_len)
            || !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
            || !EVP_DigestFinal(hash, computed_C3, NULL)) {
        SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
        goto done;
    }

    if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
        SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
        goto done;
    }

    rc = 1;
    *ptext_len = msg_len;

 done:
    if (rc == 0)
        memset(ptext_buf, 0, *ptext_len);

    OPENSSL_free(msg_mask);
    OPENSSL_free(x2y2);
    OPENSSL_free(computed_C3);
    EC_POINT_free(C1);
    BN_CTX_free(ctx);
    SM2_Ciphertext_free(sm2_ctext);
    EVP_MD_CTX_free(hash);

    return rc;
}

Coverage Report

Created: 2023-09-25 06:41

Line	Count	Source (jump to first uncovered line)
1		/*
2		* Copyright 2017-2021 The OpenSSL Project Authors. All Rights Reserved.
3		* Copyright 2017 Ribose Inc. All Rights Reserved.
4		* Ported from Ribose contributions from Botan.
5		*
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
10		*/
11
12		#include "crypto/sm2.h"
13		#include "crypto/sm2err.h"
14		#include "crypto/ec.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>
20		#include <string.h>
21
22		typedef struct SM2_Ciphertext_st SM2_Ciphertext;
23		DECLARE_ASN1_FUNCTIONS(SM2_Ciphertext)
24
25		struct SM2_Ciphertext_st {
26		BIGNUM *C1x;
27		BIGNUM *C1y;
28		ASN1_OCTET_STRING *C3;
29		ASN1_OCTET_STRING *C2;
30		};
31
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)
38
39		IMPLEMENT_ASN1_FUNCTIONS(SM2_Ciphertext)
40
41		static size_t ec_field_size(const EC_GROUP *group)
42	0	{
43		/* Is there some simpler way to do this? */
44	0	BIGNUM *p = BN_new();
45	0	BIGNUM *a = BN_new();
46	0	BIGNUM *b = BN_new();
47	0	size_t field_size = 0;
48
49	0	if (p == NULL \|\| a == NULL \|\| b == NULL)
50	0	goto done;
51
52	0	if (!EC_GROUP_get_curve(group, p, a, b, NULL))
53	0	goto done;
54	0	field_size = (BN_num_bits(p) + 7) / 8;
55
56	0	done:
57	0	BN_free(p);
58	0	BN_free(a);
59	0	BN_free(b);
60
61	0	return field_size;
62	0	}
63
64		int sm2_plaintext_size(const unsigned char ct, size_t ct_size, size_t pt_size)
65	0	{
66	0	struct SM2_Ciphertext_st *sm2_ctext = NULL;
67
68	0	sm2_ctext = d2i_SM2_Ciphertext(NULL, &ct, ct_size);
69
70	0	if (sm2_ctext == NULL) {
71	0	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
72	0	return 0;
73	0	}
74
75	0	*pt_size = sm2_ctext->C2->length;
76	0	SM2_Ciphertext_free(sm2_ctext);
77
78	0	return 1;
79	0	}
80
81		int sm2_ciphertext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
82		size_t *ct_size)
83	0	{
84	0	const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
85	0	const int md_size = EVP_MD_size(digest);
86	0	size_t sz;
87
88	0	if (field_size == 0 \|\| md_size < 0)
89	0	return 0;
90
91		/* Integer and string are simple type; set constructed = 0, means primitive and definite length encoding. */
92	0	sz = 2 * ASN1_object_size(0, field_size + 1, V_ASN1_INTEGER)
93	0	+ ASN1_object_size(0, md_size, V_ASN1_OCTET_STRING)
94	0	+ ASN1_object_size(0, msg_len, V_ASN1_OCTET_STRING);
95		/* Sequence is structured type; set constructed = 1, means constructed and definite length encoding. */
96	0	*ct_size = ASN1_object_size(1, sz, V_ASN1_SEQUENCE);
97
98	0	return 1;
99	0	}
100
101		int sm2_encrypt(const EC_KEY *key,
102		const EVP_MD *digest,
103		const uint8_t *msg,
104		size_t msg_len, uint8_t ciphertext_buf, size_t ciphertext_len)
105	0	{
106	0	int rc = 0, ciphertext_leni;
107	0	size_t i;
108	0	BN_CTX *ctx = NULL;
109	0	BIGNUM *k = NULL;
110	0	BIGNUM *x1 = NULL;
111	0	BIGNUM *y1 = NULL;
112	0	BIGNUM *x2 = NULL;
113	0	BIGNUM *y2 = NULL;
114	0	EVP_MD_CTX *hash = EVP_MD_CTX_new();
115	0	struct SM2_Ciphertext_st ctext_struct;
116	0	const EC_GROUP *group = EC_KEY_get0_group(key);
117	0	const BIGNUM *order = EC_GROUP_get0_order(group);
118	0	const EC_POINT *P = EC_KEY_get0_public_key(key);
119	0	EC_POINT *kG = NULL;
120	0	EC_POINT *kP = NULL;
121	0	uint8_t *msg_mask = NULL;
122	0	uint8_t *x2y2 = NULL;
123	0	uint8_t *C3 = NULL;
124	0	size_t field_size;
125	0	const int C3_size = EVP_MD_size(digest);
126
127		/* NULL these before any "goto done" */
128	0	ctext_struct.C2 = NULL;
129	0	ctext_struct.C3 = NULL;
130
131	0	if (hash == NULL \|\| C3_size <= 0) {
132	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
133	0	goto done;
134	0	}
135
136	0	field_size = ec_field_size(group);
137	0	if (field_size == 0) {
138	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
139	0	goto done;
140	0	}
141
142	0	kG = EC_POINT_new(group);
143	0	kP = EC_POINT_new(group);
144	0	ctx = BN_CTX_new();
145	0	if (kG == NULL \|\| kP == NULL \|\| ctx == NULL) {
146	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
147	0	goto done;
148	0	}
149
150	0	BN_CTX_start(ctx);
151	0	k = BN_CTX_get(ctx);
152	0	x1 = BN_CTX_get(ctx);
153	0	x2 = BN_CTX_get(ctx);
154	0	y1 = BN_CTX_get(ctx);
155	0	y2 = BN_CTX_get(ctx);
156
157	0	if (y2 == NULL) {
158	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
159	0	goto done;
160	0	}
161
162	0	x2y2 = OPENSSL_zalloc(2 * field_size);
163	0	C3 = OPENSSL_zalloc(C3_size);
164
165	0	if (x2y2 == NULL \|\| C3 == NULL) {
166	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
167	0	goto done;
168	0	}
169
170	0	memset(ciphertext_buf, 0, *ciphertext_len);
171
172	0	if (!BN_priv_rand_range(k, order)) {
173	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
174	0	goto done;
175	0	}
176
177	0	if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
178	0	\|\| !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
179	0	\|\| !EC_POINT_mul(group, kP, NULL, P, k, ctx)
180	0	\|\| !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
181	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
182	0	goto done;
183	0	}
184
185	0	if (BN_bn2binpad(x2, x2y2, field_size) < 0
186	0	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
187	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
188	0	goto done;
189	0	}
190
191	0	msg_mask = OPENSSL_zalloc(msg_len);
192	0	if (msg_mask == NULL) {
193	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
194	0	goto done;
195	0	}
196
197		/* X9.63 with no salt happens to match the KDF used in SM2 */
198	0	if (!ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
199	0	digest)) {
200	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
201	0	goto done;
202	0	}
203
204	0	for (i = 0; i != msg_len; ++i)
205	0	msg_mask[i] ^= msg[i];
206
207	0	if (EVP_DigestInit(hash, digest) == 0
208	0	\|\| EVP_DigestUpdate(hash, x2y2, field_size) == 0
209	0	\|\| EVP_DigestUpdate(hash, msg, msg_len) == 0
210	0	\|\| EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
211	0	\|\| EVP_DigestFinal(hash, C3, NULL) == 0) {
212	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
213	0	goto done;
214	0	}
215
216	0	ctext_struct.C1x = x1;
217	0	ctext_struct.C1y = y1;
218	0	ctext_struct.C3 = ASN1_OCTET_STRING_new();
219	0	ctext_struct.C2 = ASN1_OCTET_STRING_new();
220
221	0	if (ctext_struct.C3 == NULL \|\| ctext_struct.C2 == NULL) {
222	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
223	0	goto done;
224	0	}
225	0	if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
226	0	\|\| !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
227	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
228	0	goto done;
229	0	}
230
231	0	ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
232		/* Ensure cast to size_t is safe */
233	0	if (ciphertext_leni < 0) {
234	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
235	0	goto done;
236	0	}
237	0	*ciphertext_len = (size_t)ciphertext_leni;
238
239	0	rc = 1;
240
241	0	done:
242	0	ASN1_OCTET_STRING_free(ctext_struct.C2);
243	0	ASN1_OCTET_STRING_free(ctext_struct.C3);
244	0	OPENSSL_free(msg_mask);
245	0	OPENSSL_free(x2y2);
246	0	OPENSSL_free(C3);
247	0	EVP_MD_CTX_free(hash);
248	0	BN_CTX_free(ctx);
249	0	EC_POINT_free(kG);
250	0	EC_POINT_free(kP);
251	0	return rc;
252	0	}
253
254		int sm2_decrypt(const EC_KEY *key,
255		const EVP_MD *digest,
256		const uint8_t *ciphertext,
257		size_t ciphertext_len, uint8_t ptext_buf, size_t ptext_len)
258	0	{
259	0	int rc = 0;
260	0	int i;
261	0	BN_CTX *ctx = NULL;
262	0	const EC_GROUP *group = EC_KEY_get0_group(key);
263	0	EC_POINT *C1 = NULL;
264	0	struct SM2_Ciphertext_st *sm2_ctext = NULL;
265	0	BIGNUM *x2 = NULL;
266	0	BIGNUM *y2 = NULL;
267	0	uint8_t *x2y2 = NULL;
268	0	uint8_t *computed_C3 = NULL;
269	0	const size_t field_size = ec_field_size(group);
270	0	const int hash_size = EVP_MD_size(digest);
271	0	uint8_t *msg_mask = NULL;
272	0	const uint8_t *C2 = NULL;
273	0	const uint8_t *C3 = NULL;
274	0	int msg_len = 0;
275	0	EVP_MD_CTX *hash = NULL;
276
277	0	if (field_size == 0 \|\| hash_size <= 0)
278	0	goto done;
279
280	0	memset(ptext_buf, 0xFF, *ptext_len);
281
282	0	sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
283
284	0	if (sm2_ctext == NULL) {
285	0	SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
286	0	goto done;
287	0	}
288
289	0	if (sm2_ctext->C3->length != hash_size) {
290	0	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
291	0	goto done;
292	0	}
293
294	0	C2 = sm2_ctext->C2->data;
295	0	C3 = sm2_ctext->C3->data;
296	0	msg_len = sm2_ctext->C2->length;
297	0	if (*ptext_len < (size_t)msg_len) {
298	0	SM2err(SM2_F_SM2_DECRYPT, SM2_R_BUFFER_TOO_SMALL);
299	0	goto done;
300	0	}
301
302	0	ctx = BN_CTX_new();
303	0	if (ctx == NULL) {
304	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
305	0	goto done;
306	0	}
307
308	0	BN_CTX_start(ctx);
309	0	x2 = BN_CTX_get(ctx);
310	0	y2 = BN_CTX_get(ctx);
311
312	0	if (y2 == NULL) {
313	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
314	0	goto done;
315	0	}
316
317	0	msg_mask = OPENSSL_zalloc(msg_len);
318	0	x2y2 = OPENSSL_zalloc(2 * field_size);
319	0	computed_C3 = OPENSSL_zalloc(hash_size);
320
321	0	if (msg_mask == NULL \|\| x2y2 == NULL \|\| computed_C3 == NULL) {
322	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
323	0	goto done;
324	0	}
325
326	0	C1 = EC_POINT_new(group);
327	0	if (C1 == NULL) {
328	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
329	0	goto done;
330	0	}
331
332	0	if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
333	0	sm2_ctext->C1y, ctx)
334	0	\|\| !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
335	0	ctx)
336	0	\|\| !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
337	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
338	0	goto done;
339	0	}
340
341	0	if (BN_bn2binpad(x2, x2y2, field_size) < 0
342	0	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
343	0	\|\| !ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
344	0	digest)) {
345	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
346	0	goto done;
347	0	}
348
349	0	for (i = 0; i != msg_len; ++i)
350	0	ptext_buf[i] = C2[i] ^ msg_mask[i];
351
352	0	hash = EVP_MD_CTX_new();
353	0	if (hash == NULL) {
354	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
355	0	goto done;
356	0	}
357
358	0	if (!EVP_DigestInit(hash, digest)
359	0	\|\| !EVP_DigestUpdate(hash, x2y2, field_size)
360	0	\|\| !EVP_DigestUpdate(hash, ptext_buf, msg_len)
361	0	\|\| !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
362	0	\|\| !EVP_DigestFinal(hash, computed_C3, NULL)) {
363	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
364	0	goto done;
365	0	}
366
367	0	if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
368	0	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
369	0	goto done;
370	0	}
371
372	0	rc = 1;
373	0	*ptext_len = msg_len;
374
375	0	done:
376	0	if (rc == 0)
377	0	memset(ptext_buf, 0, *ptext_len);
378
379	0	OPENSSL_free(msg_mask);
380	0	OPENSSL_free(x2y2);
381	0	OPENSSL_free(computed_C3);
382	0	EC_POINT_free(C1);
383	0	BN_CTX_free(ctx);
384	0	SM2_Ciphertext_free(sm2_ctext);
385	0	EVP_MD_CTX_free(hash);
386
387	0	return rc;
388	0	}