/src/openssl/crypto/sm2/sm2_crypt.c

Source (jump to first uncovered line)
/*
 * Copyright 2017-2018 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 "internal/sm2.h"
#include "internal/sm2err.h"
#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 EC_KEY *key, const EVP_MD *digest, size_t msg_len,
                       size_t *pt_size)
{
    const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
    const int md_size = EVP_MD_size(digest);
    size_t overhead;

    if (md_size < 0) {
        SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_DIGEST);
        return 0;
    }
    if (field_size == 0) {
        SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_FIELD);
        return 0;
    }

    overhead = 10 + 2 * field_size + (size_t)md_size;
    if (msg_len <= overhead) {
        SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
        return 0;
    }

    *pt_size = msg_len - overhead;
    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_62(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;

    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_62(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: 2018-08-29 13:53

Line	Count	Source (jump to first uncovered line)
1		/*
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.
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 "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>
19		#include <string.h>
20
21		typedef struct SM2_Ciphertext_st SM2_Ciphertext;
22		DECLARE_ASN1_FUNCTIONS(SM2_Ciphertext)
23
24		struct SM2_Ciphertext_st {
25		BIGNUM *C1x;
26		BIGNUM *C1y;
27		ASN1_OCTET_STRING *C3;
28		ASN1_OCTET_STRING *C2;
29		};
30
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)
37
38		IMPLEMENT_ASN1_FUNCTIONS(SM2_Ciphertext)
39
40		static size_t ec_field_size(const EC_GROUP *group)
41	0	{
42	0	/* Is there some simpler way to do this? */
43	0	BIGNUM *p = BN_new();
44	0	BIGNUM *a = BN_new();
45	0	BIGNUM *b = BN_new();
46	0	size_t field_size = 0;
47	0
48	0	if (p == NULL \|\| a == NULL \|\| b == NULL)
49	0	goto done;
50	0
51	0	if (!EC_GROUP_get_curve(group, p, a, b, NULL))
52	0	goto done;
53	0	field_size = (BN_num_bits(p) + 7) / 8;
54	0
55	0	done:
56	0	BN_free(p);
57	0	BN_free(a);
58	0	BN_free(b);
59	0
60	0	return field_size;
61	0	}
62
63		int sm2_plaintext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
64		size_t *pt_size)
65	0	{
66	0	const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
67	0	const int md_size = EVP_MD_size(digest);
68	0	size_t overhead;
69	0
70	0	if (md_size < 0) {
71	0	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_DIGEST);
72	0	return 0;
73	0	}
74	0	if (field_size == 0) {
75	0	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_FIELD);
76	0	return 0;
77	0	}
78	0
79	0	overhead = 10 + 2 * field_size + (size_t)md_size;
80	0	if (msg_len <= overhead) {
81	0	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
82	0	return 0;
83	0	}
84	0
85	0	*pt_size = msg_len - overhead;
86	0	return 1;
87	0	}
88
89		int sm2_ciphertext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
90		size_t *ct_size)
91	0	{
92	0	const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
93	0	const int md_size = EVP_MD_size(digest);
94	0	size_t sz;
95	0
96	0	if (field_size == 0 \|\| md_size < 0)
97	0	return 0;
98	0
99	0	/* Integer and string are simple type; set constructed = 0, means primitive and definite length encoding. */
100	0	sz = 2 * ASN1_object_size(0, field_size + 1, V_ASN1_INTEGER)
101	0	+ ASN1_object_size(0, md_size, V_ASN1_OCTET_STRING)
102	0	+ ASN1_object_size(0, msg_len, V_ASN1_OCTET_STRING);
103	0	/* Sequence is structured type; set constructed = 1, means constructed and definite length encoding. */
104	0	*ct_size = ASN1_object_size(1, sz, V_ASN1_SEQUENCE);
105	0
106	0	return 1;
107	0	}
108
109		int sm2_encrypt(const EC_KEY *key,
110		const EVP_MD *digest,
111		const uint8_t *msg,
112		size_t msg_len, uint8_t ciphertext_buf, size_t ciphertext_len)
113	0	{
114	0	int rc = 0, ciphertext_leni;
115	0	size_t i;
116	0	BN_CTX *ctx = NULL;
117	0	BIGNUM *k = NULL;
118	0	BIGNUM *x1 = NULL;
119	0	BIGNUM *y1 = NULL;
120	0	BIGNUM *x2 = NULL;
121	0	BIGNUM *y2 = NULL;
122	0	EVP_MD_CTX *hash = EVP_MD_CTX_new();
123	0	struct SM2_Ciphertext_st ctext_struct;
124	0	const EC_GROUP *group = EC_KEY_get0_group(key);
125	0	const BIGNUM *order = EC_GROUP_get0_order(group);
126	0	const EC_POINT *P = EC_KEY_get0_public_key(key);
127	0	EC_POINT *kG = NULL;
128	0	EC_POINT *kP = NULL;
129	0	uint8_t *msg_mask = NULL;
130	0	uint8_t *x2y2 = NULL;
131	0	uint8_t *C3 = NULL;
132	0	size_t field_size;
133	0	const int C3_size = EVP_MD_size(digest);
134	0
135	0	/* NULL these before any "goto done" */
136	0	ctext_struct.C2 = NULL;
137	0	ctext_struct.C3 = NULL;
138	0
139	0	if (hash == NULL \|\| C3_size <= 0) {
140	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
141	0	goto done;
142	0	}
143	0
144	0	field_size = ec_field_size(group);
145	0	if (field_size == 0) {
146	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
147	0	goto done;
148	0	}
149	0
150	0	kG = EC_POINT_new(group);
151	0	kP = EC_POINT_new(group);
152	0	ctx = BN_CTX_new();
153	0	if (kG == NULL \|\| kP == NULL \|\| ctx == NULL) {
154	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
155	0	goto done;
156	0	}
157	0
158	0	BN_CTX_start(ctx);
159	0	k = BN_CTX_get(ctx);
160	0	x1 = BN_CTX_get(ctx);
161	0	x2 = BN_CTX_get(ctx);
162	0	y1 = BN_CTX_get(ctx);
163	0	y2 = BN_CTX_get(ctx);
164	0
165	0	if (y2 == NULL) {
166	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
167	0	goto done;
168	0	}
169	0
170	0	x2y2 = OPENSSL_zalloc(2 * field_size);
171	0	C3 = OPENSSL_zalloc(C3_size);
172	0
173	0	if (x2y2 == NULL \|\| C3 == NULL) {
174	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
175	0	goto done;
176	0	}
177	0
178	0	memset(ciphertext_buf, 0, *ciphertext_len);
179	0
180	0	if (!BN_priv_rand_range(k, order)) {
181	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
182	0	goto done;
183	0	}
184	0
185	0	if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
186	0	\|\| !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
187	0	\|\| !EC_POINT_mul(group, kP, NULL, P, k, ctx)
188	0	\|\| !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
189	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
190	0	goto done;
191	0	}
192	0
193	0	if (BN_bn2binpad(x2, x2y2, field_size) < 0
194	0	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
195	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
196	0	goto done;
197	0	}
198	0
199	0	msg_mask = OPENSSL_zalloc(msg_len);
200	0	if (msg_mask == NULL) {
201	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
202	0	goto done;
203	0	}
204	0
205	0	/* X9.63 with no salt happens to match the KDF used in SM2 */
206	0	if (!ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
207	0	digest)) {
208	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
209	0	goto done;
210	0	}
211	0
212	0	for (i = 0; i != msg_len; ++i)
213	0	msg_mask[i] ^= msg[i];
214	0
215	0	if (EVP_DigestInit(hash, digest) == 0
216	0	\|\| EVP_DigestUpdate(hash, x2y2, field_size) == 0
217	0	\|\| EVP_DigestUpdate(hash, msg, msg_len) == 0
218	0	\|\| EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
219	0	\|\| EVP_DigestFinal(hash, C3, NULL) == 0) {
220	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
221	0	goto done;
222	0	}
223	0
224	0	ctext_struct.C1x = x1;
225	0	ctext_struct.C1y = y1;
226	0	ctext_struct.C3 = ASN1_OCTET_STRING_new();
227	0	ctext_struct.C2 = ASN1_OCTET_STRING_new();
228	0
229	0	if (ctext_struct.C3 == NULL \|\| ctext_struct.C2 == NULL) {
230	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
231	0	goto done;
232	0	}
233	0	if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
234	0	\|\| !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
235	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
236	0	goto done;
237	0	}
238	0
239	0	ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
240	0	/* Ensure cast to size_t is safe */
241	0	if (ciphertext_leni < 0) {
242	0	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
243	0	goto done;
244	0	}
245	0	*ciphertext_len = (size_t)ciphertext_leni;
246	0
247	0	rc = 1;
248	0
249	0	done:
250	0	ASN1_OCTET_STRING_free(ctext_struct.C2);
251	0	ASN1_OCTET_STRING_free(ctext_struct.C3);
252	0	OPENSSL_free(msg_mask);
253	0	OPENSSL_free(x2y2);
254	0	OPENSSL_free(C3);
255	0	EVP_MD_CTX_free(hash);
256	0	BN_CTX_free(ctx);
257	0	EC_POINT_free(kG);
258	0	EC_POINT_free(kP);
259	0	return rc;
260	0	}
261
262		int sm2_decrypt(const EC_KEY *key,
263		const EVP_MD *digest,
264		const uint8_t *ciphertext,
265		size_t ciphertext_len, uint8_t ptext_buf, size_t ptext_len)
266	0	{
267	0	int rc = 0;
268	0	int i;
269	0	BN_CTX *ctx = NULL;
270	0	const EC_GROUP *group = EC_KEY_get0_group(key);
271	0	EC_POINT *C1 = NULL;
272	0	struct SM2_Ciphertext_st *sm2_ctext = NULL;
273	0	BIGNUM *x2 = NULL;
274	0	BIGNUM *y2 = NULL;
275	0	uint8_t *x2y2 = NULL;
276	0	uint8_t *computed_C3 = NULL;
277	0	const size_t field_size = ec_field_size(group);
278	0	const int hash_size = EVP_MD_size(digest);
279	0	uint8_t *msg_mask = NULL;
280	0	const uint8_t *C2 = NULL;
281	0	const uint8_t *C3 = NULL;
282	0	int msg_len = 0;
283	0	EVP_MD_CTX *hash = NULL;
284	0
285	0	if (field_size == 0 \|\| hash_size <= 0)
286	0	goto done;
287	0
288	0	memset(ptext_buf, 0xFF, *ptext_len);
289	0
290	0	sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
291	0
292	0	if (sm2_ctext == NULL) {
293	0	SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
294	0	goto done;
295	0	}
296	0
297	0	if (sm2_ctext->C3->length != hash_size) {
298	0	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
299	0	goto done;
300	0	}
301	0
302	0	C2 = sm2_ctext->C2->data;
303	0	C3 = sm2_ctext->C3->data;
304	0	msg_len = sm2_ctext->C2->length;
305	0
306	0	ctx = BN_CTX_new();
307	0	if (ctx == NULL) {
308	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
309	0	goto done;
310	0	}
311	0
312	0	BN_CTX_start(ctx);
313	0	x2 = BN_CTX_get(ctx);
314	0	y2 = BN_CTX_get(ctx);
315	0
316	0	if (y2 == NULL) {
317	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
318	0	goto done;
319	0	}
320	0
321	0	msg_mask = OPENSSL_zalloc(msg_len);
322	0	x2y2 = OPENSSL_zalloc(2 * field_size);
323	0	computed_C3 = OPENSSL_zalloc(hash_size);
324	0
325	0	if (msg_mask == NULL \|\| x2y2 == NULL \|\| computed_C3 == NULL) {
326	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
327	0	goto done;
328	0	}
329	0
330	0	C1 = EC_POINT_new(group);
331	0	if (C1 == NULL) {
332	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
333	0	goto done;
334	0	}
335	0
336	0	if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
337	0	sm2_ctext->C1y, ctx)
338	0	\|\| !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
339	0	ctx)
340	0	\|\| !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
341	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
342	0	goto done;
343	0	}
344	0
345	0	if (BN_bn2binpad(x2, x2y2, field_size) < 0
346	0	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
347	0	\|\| !ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
348	0	digest)) {
349	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
350	0	goto done;
351	0	}
352	0
353	0	for (i = 0; i != msg_len; ++i)
354	0	ptext_buf[i] = C2[i] ^ msg_mask[i];
355	0
356	0	hash = EVP_MD_CTX_new();
357	0	if (hash == NULL) {
358	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
359	0	goto done;
360	0	}
361	0
362	0	if (!EVP_DigestInit(hash, digest)
363	0	\|\| !EVP_DigestUpdate(hash, x2y2, field_size)
364	0	\|\| !EVP_DigestUpdate(hash, ptext_buf, msg_len)
365	0	\|\| !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
366	0	\|\| !EVP_DigestFinal(hash, computed_C3, NULL)) {
367	0	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
368	0	goto done;
369	0	}
370	0
371	0	if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
372	0	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
373	0	goto done;
374	0	}
375	0
376	0	rc = 1;
377	0	*ptext_len = msg_len;
378	0
379	0	done:
380	0	if (rc == 0)
381	0	memset(ptext_buf, 0, *ptext_len);
382	0
383	0	OPENSSL_free(msg_mask);
384	0	OPENSSL_free(x2y2);
385	0	OPENSSL_free(computed_C3);
386	0	EC_POINT_free(C1);
387	0	BN_CTX_free(ctx);
388	0	SM2_Ciphertext_free(sm2_ctext);
389	0	EVP_MD_CTX_free(hash);
390	0
391	0	return rc;
392	0	}