[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 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
 */

#include "internal/sm2.h"
#include "internal/sm2err.h"
#include "internal/ec_int.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	/*
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	*
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
e425f90f	12	#include "internal/sm2.h"
2398404e	13	#include "internal/sm2err.h"
ffd89124	14	#include "internal/ec_int.h" /* ecdh_KDF_X9_63() */
2398404e	15	#include <openssl/err.h>
3d328a44 JL	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
2167239a	41	static size_t ec_field_size(const EC_GROUP *group)
3d328a44 JL	42	{
	43	/* Is there some simpler way to do this? */
	44	BIGNUM *p = BN_new();
	45	BIGNUM *a = BN_new();
	46	BIGNUM *b = BN_new();
	47	size_t field_size = 0;
	48
	49	if (p == NULL \|\| a == NULL \|\| b == NULL)
	50	goto done;
	51
9cc570d4	52	if (!EC_GROUP_get_curve(group, p, a, b, NULL))
bdd92f4d	53	goto done;
3d328a44 JL	54	field_size = (BN_num_bits(p) + 7) / 8;
	55
	56	done:
	57	BN_free(p);
	58	BN_free(a);
	59	BN_free(b);
	60
	61	return field_size;
	62	}
	63
2167239a	64	int sm2_plaintext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
e14d6cf6	65	size_t *pt_size)
4e664750	66	{
2167239a	67	const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
e14d6cf6 MC	68	const int md_size = EVP_MD_size(digest);
e14d6cf6 MC	69	size_t overhead;
4e664750	70
e14d6cf6	71	if (md_size < 0) {
245be530	72	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_DIGEST);
e14d6cf6 MC	73	return 0;
	74	}
	75	if (field_size == 0) {
245be530	76	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_FIELD);
e14d6cf6 MC	77	return 0;
e14d6cf6 MC	78	}
4e664750	79
e14d6cf6	80	overhead = 10 + 2 * field_size + (size_t)md_size;
245be530 MC	81	if (msg_len <= overhead) {
245be530 MC	82	SM2err(SM2_F_SM2_PLAINTEXT_SIZE, SM2_R_INVALID_ENCODING);
e14d6cf6 MC	83	return 0;
	84	}
	85
	86	*pt_size = msg_len - overhead;
	87	return 1;
4e664750 JL	88	}
4e664750 JL	89
2167239a	90	int sm2_ciphertext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len,
e14d6cf6	91	size_t *ct_size)
3d328a44	92	{
2167239a	93	const size_t field_size = ec_field_size(EC_KEY_get0_group(key));
e14d6cf6	94	const int md_size = EVP_MD_size(digest);
307a494e	95	size_t sz;
e14d6cf6 MC	96
	97	if (field_size == 0 \|\| md_size < 0)
	98	return 0;
	99
307a494e	100	/* Integer and string are simple type; set constructed = 0, means primitive and definite length encoding. */
	101	sz = 2 * ASN1_object_size(0, field_size + 1, V_ASN1_INTEGER)
	102	+ ASN1_object_size(0, md_size, V_ASN1_OCTET_STRING)
	103	+ ASN1_object_size(0, msg_len, V_ASN1_OCTET_STRING);
	104	/* Sequence is structured type; set constructed = 1, means constructed and definite length encoding. */
	105	*ct_size = ASN1_object_size(1, sz, V_ASN1_SEQUENCE);
	106
e14d6cf6	107	return 1;
3d328a44 JL	108	}
3d328a44 JL	109
2167239a	110	int sm2_encrypt(const EC_KEY *key,
3d328a44 JL	111	const EVP_MD *digest,
	112	const uint8_t *msg,
	113	size_t msg_len, uint8_t ciphertext_buf, size_t ciphertext_len)
	114	{
44d3845d	115	int rc = 0, ciphertext_leni;
3d328a44 JL	116	size_t i;
	117	BN_CTX *ctx = NULL;
	118	BIGNUM *k = NULL;
	119	BIGNUM *x1 = NULL;
	120	BIGNUM *y1 = NULL;
	121	BIGNUM *x2 = NULL;
	122	BIGNUM *y2 = NULL;
3d328a44	123	EVP_MD_CTX *hash = EVP_MD_CTX_new();
3d328a44 JL	124	struct SM2_Ciphertext_st ctext_struct;
	125	const EC_GROUP *group = EC_KEY_get0_group(key);
	126	const BIGNUM *order = EC_GROUP_get0_order(group);
	127	const EC_POINT *P = EC_KEY_get0_public_key(key);
	128	EC_POINT *kG = NULL;
	129	EC_POINT *kP = NULL;
	130	uint8_t *msg_mask = NULL;
3d328a44 JL	131	uint8_t *x2y2 = NULL;
3d328a44 JL	132	uint8_t *C3 = NULL;
1829ff4b MC	133	size_t field_size;
1829ff4b MC	134	const int C3_size = EVP_MD_size(digest);
3d328a44	135
44d3845d MC	136	/* NULL these before any "goto done" */
	137	ctext_struct.C2 = NULL;
	138	ctext_struct.C3 = NULL;
	139
1829ff4b MC	140	if (hash == NULL \|\| C3_size <= 0) {
	141	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	142	goto done;
	143	}
	144
	145	field_size = ec_field_size(group);
	146	if (field_size == 0) {
44d3845d MC	147	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	148	goto done;
	149	}
3d328a44 JL	150
	151	kG = EC_POINT_new(group);
	152	kP = EC_POINT_new(group);
3d328a44	153	ctx = BN_CTX_new();
44d3845d MC	154	if (kG == NULL \|\| kP == NULL \|\| ctx == NULL) {
	155	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
	156	goto done;
	157	}
3d328a44 JL	158
	159	BN_CTX_start(ctx);
	160	k = BN_CTX_get(ctx);
	161	x1 = BN_CTX_get(ctx);
	162	x2 = BN_CTX_get(ctx);
	163	y1 = BN_CTX_get(ctx);
	164	y2 = BN_CTX_get(ctx);
	165
44d3845d	166	if (y2 == NULL) {
2398404e JL	167	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_BN_LIB);
2398404e JL	168	goto done;
44d3845d	169	}
3d328a44 JL	170
	171	x2y2 = OPENSSL_zalloc(2 * field_size);
	172	C3 = OPENSSL_zalloc(C3_size);
	173
44d3845d	174	if (x2y2 == NULL \|\| C3 == NULL) {
2398404e JL	175	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	176	goto done;
44d3845d	177	}
3d328a44 JL	178
	179	memset(ciphertext_buf, 0, *ciphertext_len);
	180
44d3845d MC	181	if (!BN_priv_rand_range(k, order)) {
44d3845d MC	182	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	183	goto done;
44d3845d	184	}
3d328a44	185
44d3845d	186	if (!EC_POINT_mul(group, kG, k, NULL, NULL, ctx)
9cc570d4	187	\|\| !EC_POINT_get_affine_coordinates(group, kG, x1, y1, ctx)
44d3845d	188	\|\| !EC_POINT_mul(group, kP, NULL, P, k, ctx)
9cc570d4	189	\|\| !EC_POINT_get_affine_coordinates(group, kP, x2, y2, ctx)) {
2398404e	190	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EC_LIB);
3d328a44	191	goto done;
44d3845d	192	}
3d328a44	193
44d3845d MC	194	if (BN_bn2binpad(x2, x2y2, field_size) < 0
	195	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0) {
	196	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	197	goto done;
44d3845d	198	}
3d328a44 JL	199
3d328a44 JL	200	msg_mask = OPENSSL_zalloc(msg_len);
44d3845d	201	if (msg_mask == NULL) {
2398404e	202	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
3d328a44	203	goto done;
44d3845d	204	}
3d328a44 JL	205
3d328a44 JL	206	/* X9.63 with no salt happens to match the KDF used in SM2 */
ffd89124	207	if (!ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
44d3845d MC	208	digest)) {
44d3845d MC	209	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
3d328a44	210	goto done;
44d3845d	211	}
3d328a44 JL	212
	213	for (i = 0; i != msg_len; ++i)
	214	msg_mask[i] ^= msg[i];
	215
44d3845d MC	216	if (EVP_DigestInit(hash, digest) == 0
	217	\|\| EVP_DigestUpdate(hash, x2y2, field_size) == 0
	218	\|\| EVP_DigestUpdate(hash, msg, msg_len) == 0
	219	\|\| EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0
	220	\|\| EVP_DigestFinal(hash, C3, NULL) == 0) {
2398404e	221	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_EVP_LIB);
3d328a44	222	goto done;
44d3845d	223	}
3d328a44 JL	224
	225	ctext_struct.C1x = x1;
	226	ctext_struct.C1y = y1;
	227	ctext_struct.C3 = ASN1_OCTET_STRING_new();
3d328a44	228	ctext_struct.C2 = ASN1_OCTET_STRING_new();
3d328a44	229
44d3845d MC	230	if (ctext_struct.C3 == NULL \|\| ctext_struct.C2 == NULL) {
	231	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_MALLOC_FAILURE);
	232	goto done;
	233	}
	234	if (!ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size)
	235	\|\| !ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len)) {
	236	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	237	goto done;
	238	}
3d328a44	239
44d3845d MC	240	ciphertext_leni = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);
	241	/* Ensure cast to size_t is safe */
	242	if (ciphertext_leni < 0) {
	243	SM2err(SM2_F_SM2_ENCRYPT, ERR_R_INTERNAL_ERROR);
	244	goto done;
	245	}
	246	*ciphertext_len = (size_t)ciphertext_leni;
3d328a44 JL	247
	248	rc = 1;
	249
	250	done:
44d3845d MC	251	ASN1_OCTET_STRING_free(ctext_struct.C2);
44d3845d MC	252	ASN1_OCTET_STRING_free(ctext_struct.C3);
3d328a44 JL	253	OPENSSL_free(msg_mask);
	254	OPENSSL_free(x2y2);
	255	OPENSSL_free(C3);
	256	EVP_MD_CTX_free(hash);
	257	BN_CTX_free(ctx);
	258	EC_POINT_free(kG);
	259	EC_POINT_free(kP);
	260	return rc;
	261	}
	262
2167239a	263	int sm2_decrypt(const EC_KEY *key,
3d328a44 JL	264	const EVP_MD *digest,
	265	const uint8_t *ciphertext,
	266	size_t ciphertext_len, uint8_t ptext_buf, size_t ptext_len)
	267	{
	268	int rc = 0;
	269	int i;
3d328a44 JL	270	BN_CTX *ctx = NULL;
	271	const EC_GROUP *group = EC_KEY_get0_group(key);
	272	EC_POINT *C1 = NULL;
	273	struct SM2_Ciphertext_st *sm2_ctext = NULL;
	274	BIGNUM *x2 = NULL;
	275	BIGNUM *y2 = NULL;
3d328a44 JL	276	uint8_t *x2y2 = NULL;
3d328a44 JL	277	uint8_t *computed_C3 = NULL;
2167239a	278	const size_t field_size = ec_field_size(group);
3d328a44	279	const int hash_size = EVP_MD_size(digest);
3d328a44 JL	280	uint8_t *msg_mask = NULL;
	281	const uint8_t *C2 = NULL;
	282	const uint8_t *C3 = NULL;
	283	int msg_len = 0;
	284	EVP_MD_CTX *hash = NULL;
	285
1829ff4b	286	if (field_size == 0 \|\| hash_size <= 0)
3d328a44 JL	287	goto done;
	288
	289	memset(ptext_buf, 0xFF, *ptext_len);
	290
	291	sm2_ctext = d2i_SM2_Ciphertext(NULL, &ciphertext, ciphertext_len);
	292
245be530	293	if (sm2_ctext == NULL) {
2398404e	294	SM2err(SM2_F_SM2_DECRYPT, SM2_R_ASN1_ERROR);
3d328a44	295	goto done;
245be530	296	}
3d328a44	297
245be530	298	if (sm2_ctext->C3->length != hash_size) {
2398404e	299	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_ENCODING);
3d328a44	300	goto done;
245be530	301	}
3d328a44 JL	302
	303	C2 = sm2_ctext->C2->data;
	304	C3 = sm2_ctext->C3->data;
	305	msg_len = sm2_ctext->C2->length;
	306
	307	ctx = BN_CTX_new();
245be530	308	if (ctx == NULL) {
2398404e JL	309	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	310	goto done;
245be530	311	}
3d328a44 JL	312
	313	BN_CTX_start(ctx);
	314	x2 = BN_CTX_get(ctx);
	315	y2 = BN_CTX_get(ctx);
	316
245be530	317	if (y2 == NULL) {
2398404e JL	318	SM2err(SM2_F_SM2_DECRYPT, ERR_R_BN_LIB);
2398404e JL	319	goto done;
245be530	320	}
3d328a44 JL	321
	322	msg_mask = OPENSSL_zalloc(msg_len);
	323	x2y2 = OPENSSL_zalloc(2 * field_size);
	324	computed_C3 = OPENSSL_zalloc(hash_size);
	325
245be530	326	if (msg_mask == NULL \|\| x2y2 == NULL \|\| computed_C3 == NULL) {
2398404e JL	327	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	328	goto done;
245be530	329	}
3d328a44 JL	330
3d328a44 JL	331	C1 = EC_POINT_new(group);
245be530	332	if (C1 == NULL) {
2398404e	333	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
3d328a44	334	goto done;
245be530	335	}
3d328a44	336
9cc570d4 MC	337	if (!EC_POINT_set_affine_coordinates(group, C1, sm2_ctext->C1x,
9cc570d4 MC	338	sm2_ctext->C1y, ctx)
245be530 MC	339	\|\| !EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key),
245be530 MC	340	ctx)
9cc570d4	341	\|\| !EC_POINT_get_affine_coordinates(group, C1, x2, y2, ctx)) {
2398404e	342	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EC_LIB);
3d328a44	343	goto done;
245be530	344	}
3d328a44	345
245be530 MC	346	if (BN_bn2binpad(x2, x2y2, field_size) < 0
245be530 MC	347	\|\| BN_bn2binpad(y2, x2y2 + field_size, field_size) < 0
ffd89124	348	\|\| !ecdh_KDF_X9_63(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0,
245be530 MC	349	digest)) {
245be530 MC	350	SM2err(SM2_F_SM2_DECRYPT, ERR_R_INTERNAL_ERROR);
3d328a44	351	goto done;
245be530	352	}
3d328a44 JL	353
	354	for (i = 0; i != msg_len; ++i)
	355	ptext_buf[i] = C2[i] ^ msg_mask[i];
	356
	357	hash = EVP_MD_CTX_new();
245be530	358	if (hash == NULL) {
2398404e JL	359	SM2err(SM2_F_SM2_DECRYPT, ERR_R_MALLOC_FAILURE);
2398404e JL	360	goto done;
245be530	361	}
3d328a44	362
245be530 MC	363	if (!EVP_DigestInit(hash, digest)
	364	\|\| !EVP_DigestUpdate(hash, x2y2, field_size)
	365	\|\| !EVP_DigestUpdate(hash, ptext_buf, msg_len)
	366	\|\| !EVP_DigestUpdate(hash, x2y2 + field_size, field_size)
	367	\|\| !EVP_DigestFinal(hash, computed_C3, NULL)) {
2398404e	368	SM2err(SM2_F_SM2_DECRYPT, ERR_R_EVP_LIB);
3d328a44	369	goto done;
245be530	370	}
3d328a44	371
245be530 MC	372	if (CRYPTO_memcmp(computed_C3, C3, hash_size) != 0) {
245be530 MC	373	SM2err(SM2_F_SM2_DECRYPT, SM2_R_INVALID_DIGEST);
3d328a44	374	goto done;
245be530	375	}
3d328a44 JL	376
3d328a44 JL	377	rc = 1;
dceb99a5	378	*ptext_len = msg_len;
3d328a44 JL	379
3d328a44 JL	380	done:
3d328a44 JL	381	if (rc == 0)
	382	memset(ptext_buf, 0, *ptext_len);
	383
	384	OPENSSL_free(msg_mask);
	385	OPENSSL_free(x2y2);
	386	OPENSSL_free(computed_C3);
	387	EC_POINT_free(C1);
	388	BN_CTX_free(ctx);
	389	SM2_Ciphertext_free(sm2_ctext);
	390	EVP_MD_CTX_free(hash);
	391
	392	return rc;
	393	}