crypto/sm2/sm2_crypt.c - third_party/openssl - Git at Google

 /*
  * 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 <openssl/sm2.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;
 }

 size_t SM2_plaintext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len)
 {
     const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
     const size_t md_size = EVP_MD_size(digest);

     const size_t overhead = 10 + 2 * field_size + md_size;
     if(msg_len <= overhead)
        return 0;

     return msg_len - overhead;
 }

 size_t SM2_ciphertext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len)
 {
     const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
     const size_t md_size = EVP_MD_size(digest);
     return 10 + 2 * field_size + md_size + msg_len;
 }

 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;
     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);

     if (field_size == 0 || C3_size == 0)
        goto done;

     kG = EC_POINT_new(group);
     kP = EC_POINT_new(group);
     if (kG == NULL || kP == NULL)
        goto done;

     ctx = BN_CTX_new();
     if (ctx == NULL)
        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)
        goto done;

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

     if (x2y2 == NULL || C3 == NULL)
        goto done;

     memset(ciphertext_buf, 0, *ciphertext_len);

     BN_priv_rand_range(k, order);

     if (EC_POINT_mul(group, kG, k, NULL, NULL, ctx) == 0)
         goto done;

     if (EC_POINT_get_affine_coordinates_GFp(group, kG, x1, y1, ctx) == 0)
         goto done;

     if (EC_POINT_mul(group, kP, NULL, P, k, ctx) == 0)
         goto done;

     if (EC_POINT_get_affine_coordinates_GFp(group, kP, x2, y2, ctx) == 0)
         goto done;

     BN_bn2binpad(x2, x2y2, field_size);
     BN_bn2binpad(y2, x2y2 + field_size, field_size);

     msg_mask = OPENSSL_zalloc(msg_len);
     if (msg_mask == NULL)
        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)
         == 0)
         goto done;

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

     if (EVP_DigestInit(hash, digest) == 0)
         goto done;

     if (EVP_DigestUpdate(hash, x2y2, field_size) == 0)
         goto done;

     if (EVP_DigestUpdate(hash, msg, msg_len) == 0)
         goto done;

     if (EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0)
         goto done;

     if (EVP_DigestFinal(hash, C3, NULL) == 0)
         goto done;

     ctext_struct.C1x = x1;
     ctext_struct.C1y = y1;
     ctext_struct.C3 = ASN1_OCTET_STRING_new();
     ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size);
     ctext_struct.C2 = ASN1_OCTET_STRING_new();
     ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len);

     *ciphertext_len = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);

     ASN1_OCTET_STRING_free(ctext_struct.C2);
     ASN1_OCTET_STRING_free(ctext_struct.C3);

     rc = 1;

  done:
     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)
         goto done;

     if (sm2_ctext->C3->length != hash_size)
         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)
        goto done;

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

     if(y2 == NULL)
        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)
        goto done;

     C1 = EC_POINT_new(group);
     if (C1 == NULL)
         goto done;

     if (EC_POINT_set_affine_coordinates_GFp
         (group, C1, sm2_ctext->C1x, sm2_ctext->C1y, ctx) == 0)
         goto done;

     if (EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key), ctx) ==
         0)
         goto done;

     if (EC_POINT_get_affine_coordinates_GFp(group, C1, x2, y2, ctx) == 0)
         goto done;

     BN_bn2binpad(x2, x2y2, field_size);
     BN_bn2binpad(y2, x2y2 + field_size, field_size);

     if (ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0, digest)
         == 0)
         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)
        goto done;

     if (EVP_DigestInit(hash, digest) == 0)
         goto done;

     if (EVP_DigestUpdate(hash, x2y2, field_size) == 0)
         goto done;

     if (EVP_DigestUpdate(hash, ptext_buf, msg_len) == 0)
         goto done;

     if (EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0)
         goto done;

     if (EVP_DigestFinal(hash, computed_C3, NULL) == 0)
         goto done;

     if (memcmp(computed_C3, C3, hash_size) != 0)
         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;
 }
	/*
	* 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 <openssl/sm2.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;
	}

	size_t SM2_plaintext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len)
	{
	const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
	const size_t md_size = EVP_MD_size(digest);

	const size_t overhead = 10 + 2 * field_size + md_size;
	if(msg_len <= overhead)
	return 0;

	return msg_len - overhead;
	}

	size_t SM2_ciphertext_size(const EC_KEY key, const EVP_MD digest, size_t msg_len)
	{
	const size_t field_size = EC_field_size(EC_KEY_get0_group(key));
	const size_t md_size = EVP_MD_size(digest);
	return 10 + 2 * field_size + md_size + msg_len;
	}

	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;
	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);

	if (field_size == 0 \|\| C3_size == 0)
	goto done;

	kG = EC_POINT_new(group);
	kP = EC_POINT_new(group);
	if (kG == NULL \|\| kP == NULL)
	goto done;

	ctx = BN_CTX_new();
	if (ctx == NULL)
	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)
	goto done;

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

	if (x2y2 == NULL \|\| C3 == NULL)
	goto done;

	memset(ciphertext_buf, 0, *ciphertext_len);

	BN_priv_rand_range(k, order);

	if (EC_POINT_mul(group, kG, k, NULL, NULL, ctx) == 0)
	goto done;

	if (EC_POINT_get_affine_coordinates_GFp(group, kG, x1, y1, ctx) == 0)
	goto done;

	if (EC_POINT_mul(group, kP, NULL, P, k, ctx) == 0)
	goto done;

	if (EC_POINT_get_affine_coordinates_GFp(group, kP, x2, y2, ctx) == 0)
	goto done;

	BN_bn2binpad(x2, x2y2, field_size);
	BN_bn2binpad(y2, x2y2 + field_size, field_size);

	msg_mask = OPENSSL_zalloc(msg_len);
	if (msg_mask == NULL)
	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)
	== 0)
	goto done;

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

	if (EVP_DigestInit(hash, digest) == 0)
	goto done;

	if (EVP_DigestUpdate(hash, x2y2, field_size) == 0)
	goto done;

	if (EVP_DigestUpdate(hash, msg, msg_len) == 0)
	goto done;

	if (EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0)
	goto done;

	if (EVP_DigestFinal(hash, C3, NULL) == 0)
	goto done;

	ctext_struct.C1x = x1;
	ctext_struct.C1y = y1;
	ctext_struct.C3 = ASN1_OCTET_STRING_new();
	ASN1_OCTET_STRING_set(ctext_struct.C3, C3, C3_size);
	ctext_struct.C2 = ASN1_OCTET_STRING_new();
	ASN1_OCTET_STRING_set(ctext_struct.C2, msg_mask, msg_len);

	*ciphertext_len = i2d_SM2_Ciphertext(&ctext_struct, &ciphertext_buf);

	ASN1_OCTET_STRING_free(ctext_struct.C2);
	ASN1_OCTET_STRING_free(ctext_struct.C3);

	rc = 1;

	done:
	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)
	goto done;

	if (sm2_ctext->C3->length != hash_size)
	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)
	goto done;

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

	if(y2 == NULL)
	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)
	goto done;

	C1 = EC_POINT_new(group);
	if (C1 == NULL)
	goto done;

	if (EC_POINT_set_affine_coordinates_GFp
	(group, C1, sm2_ctext->C1x, sm2_ctext->C1y, ctx) == 0)
	goto done;

	if (EC_POINT_mul(group, C1, NULL, C1, EC_KEY_get0_private_key(key), ctx) ==
	0)
	goto done;

	if (EC_POINT_get_affine_coordinates_GFp(group, C1, x2, y2, ctx) == 0)
	goto done;

	BN_bn2binpad(x2, x2y2, field_size);
	BN_bn2binpad(y2, x2y2 + field_size, field_size);

	if (ECDH_KDF_X9_62(msg_mask, msg_len, x2y2, 2 * field_size, NULL, 0, digest)
	== 0)
	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)
	goto done;

	if (EVP_DigestInit(hash, digest) == 0)
	goto done;

	if (EVP_DigestUpdate(hash, x2y2, field_size) == 0)
	goto done;

	if (EVP_DigestUpdate(hash, ptext_buf, msg_len) == 0)
	goto done;

	if (EVP_DigestUpdate(hash, x2y2 + field_size, field_size) == 0)
	goto done;

	if (EVP_DigestFinal(hash, computed_C3, NULL) == 0)
	goto done;

	if (memcmp(computed_C3, C3, hash_size) != 0)
	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;
	}