[thirdparty/openssl.git] / crypto / sm2 / sm2_crypt.c

/*
 * 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;

    EC_GROUP_get_curve_GFp(group, p, a, b, NULL);
    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);

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

    *ct_size = 10 + 2 * field_size + (size_t)md_size + msg_len;
    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;
    const size_t field_size = EC_field_size(group);
    const size_t C3_size = EVP_MD_size(digest);

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

    if (hash == NULL
            || group == NULL
            || order == NULL
            || P == NULL
            || field_size == 0
            || C3_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_GFp(group, kG, x1, y1, ctx)
            || !EC_POINT_mul(group, kP, NULL, P, k, ctx)
            || !EC_POINT_get_affine_coordinates_GFp(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_GFp(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_GFp(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;
}
Commit	Line	Data
3d328a44	1	/*
b0edda11	2	* Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved.
3d328a44 JL	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
e425f90f	12	#include "internal/sm2.h"
2398404e JL	13	#include "internal/sm2err.h"
2398404e JL	14	#include <openssl/err.h>
3d328a44 JL	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	{
	42	/* Is there some simpler way to do this? */
	43	BIGNUM *p = BN_new();
	44	BIGNUM *a = BN_new();
	45	BIGNUM *b = BN_new();
	46	size_t field_size = 0;
	47
	48	if (p == NULL \|\| a == NULL \|\| b == NULL)
	49	goto done;
	50
	51	EC_GROUP_get_curve_GFp(group, p, a, b, NULL);
	52	field_size = (BN_num_bits(p) + 7) / 8;
	53
	54	done:
	55	BN_free(p);
	56	BN_free(a);
	57	BN_free(b);
	58
	59	return field_size;
	60	}
	61
e14d6cf6 MC	62	int SM2_plaintext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
e14d6cf6 MC	63	size_t *pt_size)
4e664750 JL	64	{
4e664750 JL	65	const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
e14d6cf6 MC	66	const int md_size = EVP_MD_size(digest);
e14d6cf6 MC	67	size_t overhead;
4e664750	68
e14d6cf6	69	if (md_size < 0) {
245be530	70	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_DIGEST);
e14d6cf6 MC	71	return 0;
	72	}
	73	if (field_size == 0) {
245be530	74	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_FIELD);
e14d6cf6 MC	75	return 0;
e14d6cf6 MC	76	}
4e664750	77
e14d6cf6	78	overhead = 10 + 2 * field_size + (size_t)md_size;
245be530 MC	79	if (msg_len <= overhead) {
245be530 MC	80	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
e14d6cf6 MC	81	return 0;
	82	}
	83
	84	*pt_size = msg_len - overhead;
	85	return 1;
4e664750 JL	86	}
4e664750 JL	87
e14d6cf6 MC	88	int SM2_ciphertext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
e14d6cf6 MC	89	size_t *ct_size)
3d328a44	90	{
4e664750	91	const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
e14d6cf6 MC	92	const int md_size = EVP_MD_size(digest);
	93
	94	if (field_size == 0 \|\| md_size < 0)
	95	return 0;
	96
	97	ct_size = 10 + 2 field_size + (size_t)md_size + msg_len;
	98	return 1;
3d328a44 JL	99	}
	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	{
44d3845d	106	int rc = 0, ciphertext_leni;
3d328a44 JL	107	size_t i;
	108	BN_CTX *ctx = NULL;
	109	BIGNUM *k = NULL;
	110	BIGNUM *x1 = NULL;
	111	BIGNUM *y1 = NULL;
	112	BIGNUM *x2 = NULL;
	113	BIGNUM *y2 = NULL;
3d328a44	114	EVP_MD_CTX *hash = EVP_MD_CTX_new();
3d328a44 JL	115	struct SM2_Ciphertext_st ctext_struct;
	116	const EC_GROUP *group = EC_KEY_get0_group(key);
	117	const BIGNUM *order = EC_GROUP_get0_order(group);
	118	const EC_POINT *P = EC_KEY_get0_public_key(key);
	119	EC_POINT *kG = NULL;
	120	EC_POINT *kP = NULL;
	121	uint8_t *msg_mask = NULL;
3d328a44 JL	122	uint8_t *x2y2 = NULL;
3d328a44 JL	123	uint8_t *C3 = NULL;
3d328a44 JL	124	const size_t field_size = EC_field_size(group);
	125	const size_t C3_size = EVP_MD_size(digest);
	126
44d3845d MC	127	/* NULL these before any "goto done" */
	128	ctext_struct.C2 = NULL;
	129	ctext_struct.C3 = NULL;
	130
	131	if (hash == NULL
	132	\|\| group == NULL
	133	\|\| order == NULL
	134	\|\| P == NULL
	135	\|\| field_size == 0
	136	\|\| C3_size == 0) {
	137	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	138	goto done;
	139	}
3d328a44 JL	140
	141	kG = EC_POINT_new(group);
	142	kP = EC_POINT_new(group);
3d328a44	143	ctx = BN_CTX_new();
44d3845d MC	144	if (kG == NULL \|\| kP == NULL \|\| ctx == NULL) {
	145	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
	146	goto done;
	147	}
3d328a44 JL	148
	149	BN_CTX_start(ctx);
	150	k = BN_CTX_get(ctx);
	151	x1 = BN_CTX_get(ctx);
	152	x2 = BN_CTX_get(ctx);
	153	y1 = BN_CTX_get(ctx);
	154	y2 = BN_CTX_get(ctx);
	155
44d3845d	156	if (y2 == NULL) {
2398404e JL	157	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
2398404e JL	158	goto done;
44d3845d	159	}
3d328a44 JL	160
	161	x2y2 = OPENSSL_zalloc(2 * field_size);
	162	C3 = OPENSSL_zalloc(C3_size);
	163
44d3845d	164	if (x2y2 == NULL \|\| C3 == NULL) {
2398404e JL	165	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	166	goto done;
44d3845d	167	}
3d328a44 JL	168
	169	memset(ciphertext_buf, 0, *ciphertext_len);
	170
44d3845d MC	171	if (!BN_priv_rand_range(k, order)) {
44d3845d MC	172	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	173	goto done;
44d3845d	174	}
3d328a44	175
44d3845d MC	176	if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
	177	\|\| !EC_POINT_get_affine_coordinates_GFp(group, kG, x1, y1, ctx)
	178	\|\| !EC_POINT_mul(group, kP, NULL, P, k, ctx)
	179	\|\| !EC_POINT_get_affine_coordinates_GFp(group, kP, x2, y2, ctx)) {
2398404e	180	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
3d328a44	181	goto done;
44d3845d	182	}
3d328a44	183
44d3845d MC	184	if (BN_bn2binpad(x2, x2y2, field_size) < 0
	185	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
	186	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	187	goto done;
44d3845d	188	}
3d328a44 JL	189
3d328a44 JL	190	msg_mask = OPENSSL_zalloc(msg_len);
44d3845d	191	if (msg_mask == NULL) {
2398404e	192	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
3d328a44	193	goto done;
44d3845d	194	}
3d328a44 JL	195
3d328a44 JL	196	/* X9.63 with no salt happens to match the KDF used in SM2 */
44d3845d MC	197	if (!ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
	198	digest)) {
	199	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
3d328a44	200	goto done;
44d3845d	201	}
3d328a44 JL	202
	203	for (i = 0; i != msg_len; ++i)
	204	msg_mask[i] ^= msg[i];
	205
44d3845d MC	206	if (EVP_DigestInit(hash, digest) == 0
	207	\|\| EVP_DigestUpdate(hash, x2y2, field_size) == 0
	208	\|\| EVP_DigestUpdate(hash, msg, msg_len) == 0
	209	\|\| EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
	210	\|\| EVP_DigestFinal(hash, C3, NULL) == 0) {
2398404e	211	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
3d328a44	212	goto done;
44d3845d	213	}
3d328a44 JL	214
	215	ctext_struct.C1x = x1;
	216	ctext_struct.C1y = y1;
	217	ctext_struct.C3 = ASN1_OCTET_STRING_new();
3d328a44	218	ctext_struct.C2 = ASN1_OCTET_STRING_new();
3d328a44	219
44d3845d MC	220	if (ctext_struct.C3 == NULL \|\| ctext_struct.C2 == NULL) {
	221	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
	222	goto done;
	223	}
	224	if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
	225	\|\| !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
	226	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	227	goto done;
	228	}
3d328a44	229
44d3845d MC	230	ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
	231	/* Ensure cast to size_t is safe */
	232	if (ciphertext_leni < 0) {
	233	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	234	goto done;
	235	}
	236	*ciphertext_len = (size_t)ciphertext_leni;
3d328a44 JL	237
	238	rc = 1;
	239
	240	done:
44d3845d MC	241	ASN1_OCTET_STRING_free(ctext_struct.C2);
44d3845d MC	242	ASN1_OCTET_STRING_free(ctext_struct.C3);
3d328a44 JL	243	OPENSSL_free(msg_mask);
	244	OPENSSL_free(x2y2);
	245	OPENSSL_free(C3);
	246	EVP_MD_CTX_free(hash);
	247	BN_CTX_free(ctx);
	248	EC_POINT_free(kG);
	249	EC_POINT_free(kP);
	250	return rc;
	251	}
	252
	253	int SM2_decrypt(const EC_KEY *key,
	254	const EVP_MD *digest,
	255	const uint8_t *ciphertext,
	256	size_t ciphertext_len, uint8_t ptext_buf, size_t ptext_len)
	257	{
	258	int rc = 0;
	259	int i;
3d328a44 JL	260	BN_CTX *ctx = NULL;
	261	const EC_GROUP *group = EC_KEY_get0_group(key);
	262	EC_POINT *C1 = NULL;
	263	struct SM2_Ciphertext_st *sm2_ctext = NULL;
	264	BIGNUM *x2 = NULL;
	265	BIGNUM *y2 = NULL;
3d328a44 JL	266	uint8_t *x2y2 = NULL;
3d328a44 JL	267	uint8_t *computed_C3 = NULL;
3d328a44 JL	268	const size_t field_size = EC_field_size(group);
3d328a44 JL	269	const int hash_size = EVP_MD_size(digest);
3d328a44 JL	270	uint8_t *msg_mask = NULL;
	271	const uint8_t *C2 = NULL;
	272	const uint8_t *C3 = NULL;
	273	int msg_len = 0;
	274	EVP_MD_CTX *hash = NULL;
	275
	276	if (field_size == 0 \|\| hash_size == 0)
	277	goto done;
	278
	279	memset(ptext_buf, 0xFF, *ptext_len);
	280
	281	sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
	282
245be530	283	if (sm2_ctext == NULL) {
2398404e	284	SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
3d328a44	285	goto done;
245be530	286	}
3d328a44	287
245be530	288	if (sm2_ctext->C3->length != hash_size) {
2398404e	289	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
3d328a44	290	goto done;
245be530	291	}
3d328a44 JL	292
	293	C2 = sm2_ctext->C2->data;
	294	C3 = sm2_ctext->C3->data;
	295	msg_len = sm2_ctext->C2->length;
	296
	297	ctx = BN_CTX_new();
245be530	298	if (ctx == NULL) {
2398404e JL	299	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	300	goto done;
245be530	301	}
3d328a44 JL	302
	303	BN_CTX_start(ctx);
	304	x2 = BN_CTX_get(ctx);
	305	y2 = BN_CTX_get(ctx);
	306
245be530	307	if (y2 == NULL) {
2398404e JL	308	SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
2398404e JL	309	goto done;
245be530	310	}
3d328a44 JL	311
	312	msg_mask = OPENSSL_zalloc(msg_len);
	313	x2y2 = OPENSSL_zalloc(2 * field_size);
	314	computed_C3 = OPENSSL_zalloc(hash_size);
	315
245be530	316	if (msg_mask == NULL \|\| x2y2 == NULL \|\| computed_C3 == NULL) {
2398404e JL	317	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	318	goto done;
245be530	319	}
3d328a44 JL	320
3d328a44 JL	321	C1 = EC_POINT_new(group);
245be530	322	if (C1 == NULL) {
2398404e	323	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
3d328a44	324	goto done;
245be530	325	}
3d328a44	326
245be530 MC	327	if (!EC_POINT_set_affine_coordinates_GFp(group, C1, sm2_ctext->C1x,
	328	sm2_ctext->C1y, ctx)
	329	\|\| !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
	330	ctx)
	331	\|\| !EC_POINT_get_affine_coordinates_GFp(group, C1, x2, y2, ctx)) {
2398404e	332	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
3d328a44	333	goto done;
245be530	334	}
3d328a44	335
245be530 MC	336	if (BN_bn2binpad(x2, x2y2, field_size) < 0
	337	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
	338	\|\| !ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
	339	digest)) {
	340	SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	341	goto done;
245be530	342	}
3d328a44 JL	343
	344	for (i = 0; i != msg_len; ++i)
	345	ptext_buf[i] = C2[i] ^ msg_mask[i];
	346
	347	hash = EVP_MD_CTX_new();
245be530	348	if (hash == NULL) {
2398404e JL	349	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	350	goto done;
245be530	351	}
3d328a44	352
245be530 MC	353	if (!EVP_DigestInit(hash, digest)
	354	\|\| !EVP_DigestUpdate(hash, x2y2, field_size)
	355	\|\| !EVP_DigestUpdate(hash, ptext_buf, msg_len)
	356	\|\| !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
	357	\|\| !EVP_DigestFinal(hash, computed_C3, NULL)) {
2398404e	358	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
3d328a44	359	goto done;
245be530	360	}
3d328a44	361
245be530 MC	362	if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
245be530 MC	363	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
3d328a44	364	goto done;
245be530	365	}
3d328a44 JL	366
3d328a44 JL	367	rc = 1;
dceb99a5	368	*ptext_len = msg_len;
3d328a44 JL	369
3d328a44 JL	370	done:
3d328a44 JL	371	if (rc == 0)
	372	memset(ptext_buf, 0, *ptext_len);
	373
	374	OPENSSL_free(msg_mask);
	375	OPENSSL_free(x2y2);
	376	OPENSSL_free(computed_C3);
	377	EC_POINT_free(C1);
	378	BN_CTX_free(ctx);
	379	SM2_Ciphertext_free(sm2_ctext);
	380	EVP_MD_CTX_free(hash);
	381
	382	return rc;
	383	}