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

/*
 * Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.
 * Copyright 2017 Ribose Inc. All Rights Reserved.
 * Ported from Ribose contributions from Botan.
 *
 * Licensed under the Apache License 2.0 (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
 */

/*
 * ECDSA low level APIs are deprecated for public use, but still ok for
 * internal use.
 */
#include "internal/deprecated.h"

#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 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_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;

    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;
}
Commit	Line	Data
3d328a44	1	/*
33388b44	2	* Copyright 2017-2020 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	*
f9f859ad	6	* Licensed under the Apache License 2.0 (the "License"). You may not use
3d328a44 JL	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
579422c8 P	12	/*
	13	* ECDSA low level APIs are deprecated for public use, but still ok for
	14	* internal use.
	15	*/
	16	#include "internal/deprecated.h"
	17
25f2138b DMSP	18	#include "crypto/sm2.h"
	19	#include "crypto/sm2err.h"
	20	#include "crypto/ec.h" /* ecdh_KDF_X9_63() */
2398404e	21	#include <openssl/err.h>
3d328a44 JL	22	#include <openssl/evp.h>
	23	#include <openssl/bn.h>
	24	#include <openssl/asn1.h>
	25	#include <openssl/asn1t.h>
	26	#include <string.h>
	27
	28	typedef struct SM2_Ciphertext_st SM2_Ciphertext;
	29	DECLARE_ASN1_FUNCTIONS(SM2_Ciphertext)
	30
	31	struct SM2_Ciphertext_st {
	32	BIGNUM *C1x;
	33	BIGNUM *C1y;
	34	ASN1_OCTET_STRING *C3;
	35	ASN1_OCTET_STRING *C2;
	36	};
	37
	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)
	44
	45	IMPLEMENT_ASN1_FUNCTIONS(SM2_Ciphertext)
	46
2167239a	47	static size_t ec_field_size(const EC_GROUP *group)
3d328a44 JL	48	{
	49	/* Is there some simpler way to do this? */
	50	BIGNUM *p = BN_new();
	51	BIGNUM *a = BN_new();
	52	BIGNUM *b = BN_new();
	53	size_t field_size = 0;
	54
	55	if (p == NULL \|\| a == NULL \|\| b == NULL)
	56	goto done;
	57
9cc570d4	58	if (!EC_GROUP_get_curve(group, p, a, b, NULL))
bdd92f4d	59	goto done;
3d328a44 JL	60	field_size = (BN_num_bits(p) + 7) / 8;
	61
	62	done:
	63	BN_free(p);
	64	BN_free(a);
	65	BN_free(b);
	66
	67	return field_size;
	68	}
	69
2167239a	70	int sm2_plaintext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
e14d6cf6	71	size_t *pt_size)
4e664750	72	{
2167239a	73	const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
e14d6cf6 MC	74	const int md_size = EVP_MD_size(digest);
e14d6cf6 MC	75	size_t overhead;
4e664750	76
e14d6cf6	77	if (md_size < 0) {
245be530	78	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_DIGEST);
e14d6cf6 MC	79	return 0;
	80	}
	81	if (field_size == 0) {
245be530	82	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_FIELD);
e14d6cf6 MC	83	return 0;
e14d6cf6 MC	84	}
4e664750	85
e14d6cf6	86	overhead = 10 + 2 * field_size + (size_t)md_size;
245be530 MC	87	if (msg_len <= overhead) {
245be530 MC	88	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
e14d6cf6 MC	89	return 0;
	90	}
	91
	92	*pt_size = msg_len - overhead;
	93	return 1;
4e664750 JL	94	}
4e664750 JL	95
2167239a	96	int sm2_ciphertext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
e14d6cf6	97	size_t *ct_size)
3d328a44	98	{
2167239a	99	const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
e14d6cf6	100	const int md_size = EVP_MD_size(digest);
307a494e	101	size_t sz;
e14d6cf6 MC	102
	103	if (field_size == 0 \|\| md_size < 0)
	104	return 0;
	105
307a494e	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);
	112
e14d6cf6	113	return 1;
3d328a44 JL	114	}
3d328a44 JL	115
2167239a	116	int sm2_encrypt(const EC_KEY *key,
3d328a44 JL	117	const EVP_MD *digest,
	118	const uint8_t *msg,
	119	size_t msg_len, uint8_t ciphertext_buf, size_t ciphertext_len)
	120	{
44d3845d	121	int rc = 0, ciphertext_leni;
3d328a44 JL	122	size_t i;
	123	BN_CTX *ctx = NULL;
	124	BIGNUM *k = NULL;
	125	BIGNUM *x1 = NULL;
	126	BIGNUM *y1 = NULL;
	127	BIGNUM *x2 = NULL;
	128	BIGNUM *y2 = NULL;
3d328a44	129	EVP_MD_CTX *hash = EVP_MD_CTX_new();
3d328a44 JL	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);
	134	EC_POINT *kG = NULL;
	135	EC_POINT *kP = NULL;
	136	uint8_t *msg_mask = NULL;
3d328a44 JL	137	uint8_t *x2y2 = NULL;
3d328a44 JL	138	uint8_t *C3 = NULL;
1829ff4b MC	139	size_t field_size;
1829ff4b MC	140	const int C3_size = EVP_MD_size(digest);
3d328a44	141
44d3845d MC	142	/* NULL these before any "goto done" */
	143	ctext_struct.C2 = NULL;
	144	ctext_struct.C3 = NULL;
	145
1829ff4b MC	146	if (hash == NULL \|\| C3_size <= 0) {
	147	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	148	goto done;
	149	}
	150
	151	field_size = ec_field_size(group);
	152	if (field_size == 0) {
44d3845d MC	153	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	154	goto done;
	155	}
3d328a44 JL	156
	157	kG = EC_POINT_new(group);
	158	kP = EC_POINT_new(group);
3d328a44	159	ctx = BN_CTX_new();
44d3845d MC	160	if (kG == NULL \|\| kP == NULL \|\| ctx == NULL) {
	161	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
	162	goto done;
	163	}
3d328a44 JL	164
	165	BN_CTX_start(ctx);
	166	k = BN_CTX_get(ctx);
	167	x1 = BN_CTX_get(ctx);
	168	x2 = BN_CTX_get(ctx);
	169	y1 = BN_CTX_get(ctx);
	170	y2 = BN_CTX_get(ctx);
	171
44d3845d	172	if (y2 == NULL) {
2398404e JL	173	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
2398404e JL	174	goto done;
44d3845d	175	}
3d328a44 JL	176
	177	x2y2 = OPENSSL_zalloc(2 * field_size);
	178	C3 = OPENSSL_zalloc(C3_size);
	179
44d3845d	180	if (x2y2 == NULL \|\| C3 == NULL) {
2398404e JL	181	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	182	goto done;
44d3845d	183	}
3d328a44 JL	184
	185	memset(ciphertext_buf, 0, *ciphertext_len);
	186
44d3845d MC	187	if (!BN_priv_rand_range(k, order)) {
44d3845d MC	188	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	189	goto done;
44d3845d	190	}
3d328a44	191
44d3845d	192	if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
9cc570d4	193	\|\| !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
44d3845d	194	\|\| !EC_POINT_mul(group, kP, NULL, P, k, ctx)
9cc570d4	195	\|\| !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
2398404e	196	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
3d328a44	197	goto done;
44d3845d	198	}
3d328a44	199
44d3845d MC	200	if (BN_bn2binpad(x2, x2y2, field_size) < 0
	201	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
	202	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	203	goto done;
44d3845d	204	}
3d328a44 JL	205
3d328a44 JL	206	msg_mask = OPENSSL_zalloc(msg_len);
44d3845d	207	if (msg_mask == NULL) {
2398404e	208	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
3d328a44	209	goto done;
44d3845d	210	}
3d328a44 JL	211
3d328a44 JL	212	/* X9.63 with no salt happens to match the KDF used in SM2 */
ffd89124	213	if (!ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
44d3845d MC	214	digest)) {
44d3845d MC	215	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
3d328a44	216	goto done;
44d3845d	217	}
3d328a44 JL	218
	219	for (i = 0; i != msg_len; ++i)
	220	msg_mask[i] ^= msg[i];
	221
44d3845d MC	222	if (EVP_DigestInit(hash, digest) == 0
	223	\|\| EVP_DigestUpdate(hash, x2y2, field_size) == 0
	224	\|\| EVP_DigestUpdate(hash, msg, msg_len) == 0
	225	\|\| EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
	226	\|\| EVP_DigestFinal(hash, C3, NULL) == 0) {
2398404e	227	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
3d328a44	228	goto done;
44d3845d	229	}
3d328a44 JL	230
	231	ctext_struct.C1x = x1;
	232	ctext_struct.C1y = y1;
	233	ctext_struct.C3 = ASN1_OCTET_STRING_new();
3d328a44	234	ctext_struct.C2 = ASN1_OCTET_STRING_new();
3d328a44	235
44d3845d MC	236	if (ctext_struct.C3 == NULL \|\| ctext_struct.C2 == NULL) {
	237	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
	238	goto done;
	239	}
	240	if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
	241	\|\| !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
	242	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	243	goto done;
	244	}
3d328a44	245
44d3845d MC	246	ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
	247	/* Ensure cast to size_t is safe */
	248	if (ciphertext_leni < 0) {
	249	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	250	goto done;
	251	}
	252	*ciphertext_len = (size_t)ciphertext_leni;
3d328a44 JL	253
	254	rc = 1;
	255
	256	done:
44d3845d MC	257	ASN1_OCTET_STRING_free(ctext_struct.C2);
44d3845d MC	258	ASN1_OCTET_STRING_free(ctext_struct.C3);
3d328a44 JL	259	OPENSSL_free(msg_mask);
	260	OPENSSL_free(x2y2);
	261	OPENSSL_free(C3);
	262	EVP_MD_CTX_free(hash);
	263	BN_CTX_free(ctx);
	264	EC_POINT_free(kG);
	265	EC_POINT_free(kP);
	266	return rc;
	267	}
	268
2167239a	269	int sm2_decrypt(const EC_KEY *key,
3d328a44 JL	270	const EVP_MD *digest,
	271	const uint8_t *ciphertext,
	272	size_t ciphertext_len, uint8_t ptext_buf, size_t ptext_len)
	273	{
	274	int rc = 0;
	275	int i;
3d328a44 JL	276	BN_CTX *ctx = NULL;
	277	const EC_GROUP *group = EC_KEY_get0_group(key);
	278	EC_POINT *C1 = NULL;
	279	struct SM2_Ciphertext_st *sm2_ctext = NULL;
	280	BIGNUM *x2 = NULL;
	281	BIGNUM *y2 = NULL;
3d328a44 JL	282	uint8_t *x2y2 = NULL;
3d328a44 JL	283	uint8_t *computed_C3 = NULL;
2167239a	284	const size_t field_size = ec_field_size(group);
3d328a44	285	const int hash_size = EVP_MD_size(digest);
3d328a44 JL	286	uint8_t *msg_mask = NULL;
	287	const uint8_t *C2 = NULL;
	288	const uint8_t *C3 = NULL;
	289	int msg_len = 0;
	290	EVP_MD_CTX *hash = NULL;
	291
1829ff4b	292	if (field_size == 0 \|\| hash_size <= 0)
3d328a44 JL	293	goto done;
	294
	295	memset(ptext_buf, 0xFF, *ptext_len);
	296
	297	sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
	298
245be530	299	if (sm2_ctext == NULL) {
2398404e	300	SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
3d328a44	301	goto done;
245be530	302	}
3d328a44	303
245be530	304	if (sm2_ctext->C3->length != hash_size) {
2398404e	305	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
3d328a44	306	goto done;
245be530	307	}
3d328a44 JL	308
	309	C2 = sm2_ctext->C2->data;
	310	C3 = sm2_ctext->C3->data;
	311	msg_len = sm2_ctext->C2->length;
	312
	313	ctx = BN_CTX_new();
245be530	314	if (ctx == NULL) {
2398404e JL	315	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	316	goto done;
245be530	317	}
3d328a44 JL	318
	319	BN_CTX_start(ctx);
	320	x2 = BN_CTX_get(ctx);
	321	y2 = BN_CTX_get(ctx);
	322
245be530	323	if (y2 == NULL) {
2398404e JL	324	SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
2398404e JL	325	goto done;
245be530	326	}
3d328a44 JL	327
	328	msg_mask = OPENSSL_zalloc(msg_len);
	329	x2y2 = OPENSSL_zalloc(2 * field_size);
	330	computed_C3 = OPENSSL_zalloc(hash_size);
	331
245be530	332	if (msg_mask == NULL \|\| x2y2 == NULL \|\| computed_C3 == NULL) {
2398404e JL	333	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	334	goto done;
245be530	335	}
3d328a44 JL	336
3d328a44 JL	337	C1 = EC_POINT_new(group);
245be530	338	if (C1 == NULL) {
2398404e	339	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
3d328a44	340	goto done;
245be530	341	}
3d328a44	342
9cc570d4 MC	343	if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
9cc570d4 MC	344	sm2_ctext->C1y, ctx)
245be530 MC	345	\|\| !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
245be530 MC	346	ctx)
9cc570d4	347	\|\| !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
2398404e	348	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
3d328a44	349	goto done;
245be530	350	}
3d328a44	351
245be530 MC	352	if (BN_bn2binpad(x2, x2y2, field_size) < 0
245be530 MC	353	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
ffd89124	354	\|\| !ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
245be530 MC	355	digest)) {
245be530 MC	356	SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	357	goto done;
245be530	358	}
3d328a44 JL	359
	360	for (i = 0; i != msg_len; ++i)
	361	ptext_buf[i] = C2[i] ^ msg_mask[i];
	362
	363	hash = EVP_MD_CTX_new();
245be530	364	if (hash == NULL) {
2398404e JL	365	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	366	goto done;
245be530	367	}
3d328a44	368
245be530 MC	369	if (!EVP_DigestInit(hash, digest)
	370	\|\| !EVP_DigestUpdate(hash, x2y2, field_size)
	371	\|\| !EVP_DigestUpdate(hash, ptext_buf, msg_len)
	372	\|\| !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
	373	\|\| !EVP_DigestFinal(hash, computed_C3, NULL)) {
2398404e	374	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
3d328a44	375	goto done;
245be530	376	}
3d328a44	377
245be530 MC	378	if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
245be530 MC	379	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
3d328a44	380	goto done;
245be530	381	}
3d328a44 JL	382
3d328a44 JL	383	rc = 1;
dceb99a5	384	*ptext_len = msg_len;
3d328a44 JL	385
3d328a44 JL	386	done:
3d328a44 JL	387	if (rc == 0)
	388	memset(ptext_buf, 0, *ptext_len);
	389
	390	OPENSSL_free(msg_mask);
	391	OPENSSL_free(x2y2);
	392	OPENSSL_free(computed_C3);
	393	EC_POINT_free(C1);
	394	BN_CTX_free(ctx);
	395	SM2_Ciphertext_free(sm2_ctext);
	396	EVP_MD_CTX_free(hash);
	397
	398	return rc;
	399	}