diff options
Diffstat (limited to 'crypto/sm2/sm2_crypt.c')
| -rw-r--r-- | crypto/sm2/sm2_crypt.c | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/crypto/sm2/sm2_crypt.c b/crypto/sm2/sm2_crypt.c new file mode 100644 index 000000000000..9c69a4505487 --- /dev/null +++ b/crypto/sm2/sm2_crypt.c @@ -0,0 +1,392 @@ +/* + * 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; + + 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_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(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_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; +} |