diff options
Diffstat (limited to 'crypto/sm2/sm2_crypt.c')
-rw-r--r-- | crypto/sm2/sm2_crypt.c | 321 |
1 files changed, 321 insertions, 0 deletions
diff --git a/crypto/sm2/sm2_crypt.c b/crypto/sm2/sm2_crypt.c new file mode 100644 index 0000000000..a450146a7b --- /dev/null +++ b/crypto/sm2/sm2_crypt.c @@ -0,0 +1,321 @@ +/* + * Copyright 2017 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_ciphertext_size(const EC_KEY *key, const EVP_MD *digest, size_t msg_len) +{ + return 10 + 2 * EC_field_size(EC_KEY_get0_group(key)) + + EVP_MD_size(digest) + 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; + + 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; +} |