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/*
* Copyright (c) 2020 Dmitry Belyavskiy <beldmit@gmail.com>
*
* Contents licensed under the terms of the OpenSSL license
* See https://www.openssl.org/source/license.html for details
*/
#include "gost_lcl.h"
#include "gost_gost2015.h"
#include "e_gost_err.h"
#include <string.h>
#include <openssl/rand.h>
int gost2015_final_call(EVP_CIPHER_CTX *ctx, EVP_MD_CTX *omac_ctx, size_t mac_size,
unsigned char *encrypted_mac,
int (*do_cipher) (EVP_CIPHER_CTX *ctx,
unsigned char *out,
const unsigned char *in,
size_t inl))
{
unsigned char calculated_mac[KUZNYECHIK_MAC_MAX_SIZE];
memset(calculated_mac, 0, KUZNYECHIK_MAC_MAX_SIZE);
if (EVP_CIPHER_CTX_encrypting(ctx)) {
EVP_DigestSignFinal(omac_ctx, calculated_mac, &mac_size);
if (do_cipher(ctx, encrypted_mac, calculated_mac, mac_size) <= 0) {
return -1;
}
} else {
unsigned char expected_mac[KUZNYECHIK_MAC_MAX_SIZE];
memset(expected_mac, 0, KUZNYECHIK_MAC_MAX_SIZE);
EVP_DigestSignFinal(omac_ctx, calculated_mac, &mac_size);
if (do_cipher(ctx, expected_mac, encrypted_mac, mac_size) <= 0) {
return -1;
}
if (CRYPTO_memcmp(expected_mac, calculated_mac, mac_size) != 0)
return -1;
}
return 0;
}
/*
* UKM = iv|kdf_seed
* */
#define MAX_GOST2015_UKM_SIZE 16
#define KDF_SEED_SIZE 8
int gost2015_get_asn1_params(const ASN1_TYPE *params, size_t ukm_size,
unsigned char *iv, size_t ukm_offset, unsigned char *kdf_seed)
{
int iv_len = 16;
GOST2015_CIPHER_PARAMS *gcp = NULL;
unsigned char *p = NULL;
memset(iv, 0, iv_len);
/* Проверяем тип params */
if (ASN1_TYPE_get(params) != V_ASN1_SEQUENCE) {
GOSTerr(GOST_F_GOST2015_GET_ASN1_PARAMS, GOST_R_INVALID_CIPHER_PARAMS);
return 0;
}
p = params->value.sequence->data;
/* Извлекаем структуру параметров */
gcp = d2i_GOST2015_CIPHER_PARAMS(NULL, (const unsigned char **)&p, params->value.sequence->length);
if (gcp == NULL) {
GOSTerr(GOST_F_GOST2015_GET_ASN1_PARAMS, GOST_R_INVALID_CIPHER_PARAMS);
return 0;
}
/* Проверяем длину синхропосылки */
if (gcp->ukm->length != (int)ukm_size) {
GOSTerr(GOST_F_GOST2015_GET_ASN1_PARAMS, GOST_R_INVALID_CIPHER_PARAMS);
GOST2015_CIPHER_PARAMS_free(gcp);
return 0;
}
memcpy(iv, gcp->ukm->data, ukm_offset);
memcpy(kdf_seed, gcp->ukm->data+ukm_offset, KDF_SEED_SIZE);
GOST2015_CIPHER_PARAMS_free(gcp);
return 1;
}
int gost2015_set_asn1_params(ASN1_TYPE *params,
const unsigned char *iv, size_t iv_size, const unsigned char *kdf_seed)
{
GOST2015_CIPHER_PARAMS *gcp = GOST2015_CIPHER_PARAMS_new();
int ret = 0, len = 0;
ASN1_OCTET_STRING *os = NULL;
unsigned char ukm_buf[MAX_GOST2015_UKM_SIZE];
unsigned char *buf = NULL;
if (gcp == NULL) {
GOSTerr(GOST_F_GOST2015_SET_ASN1_PARAMS, ERR_R_MALLOC_FAILURE);
return 0;
}
memcpy(ukm_buf, iv, iv_size);
memcpy(ukm_buf+iv_size, kdf_seed, KDF_SEED_SIZE);
if (ASN1_STRING_set(gcp->ukm, ukm_buf, iv_size + KDF_SEED_SIZE) == 0) {
GOSTerr(GOST_F_GOST2015_SET_ASN1_PARAMS, ERR_R_MALLOC_FAILURE);
goto end;
}
len = i2d_GOST2015_CIPHER_PARAMS(gcp, &buf);
if (len <= 0
|| (os = ASN1_OCTET_STRING_new()) == NULL
|| ASN1_OCTET_STRING_set(os, buf, len) == 0) {
goto end;
}
ASN1_TYPE_set(params, V_ASN1_SEQUENCE, os);
ret = 1;
end:
OPENSSL_free(buf);
if (ret <= 0 && os)
ASN1_OCTET_STRING_free(os);
GOST2015_CIPHER_PARAMS_free(gcp);
return ret;
}
int gost2015_process_unprotected_attributes(
STACK_OF(X509_ATTRIBUTE) *attrs,
int encryption, size_t mac_len, unsigned char *final_tag)
{
if (encryption == 0) /*Decrypting*/ {
ASN1_OCTET_STRING *osExpectedMac = X509at_get0_data_by_OBJ(attrs,
OBJ_txt2obj(OID_GOST_CMS_MAC, 1), -3, V_ASN1_OCTET_STRING);
if (!osExpectedMac || osExpectedMac->length != (int)mac_len)
return -1;
memcpy(final_tag, osExpectedMac->data, osExpectedMac->length);
} else {
if (attrs == NULL)
return -1;
return (X509at_add1_attr_by_OBJ(&attrs,
OBJ_txt2obj(OID_GOST_CMS_MAC, 1),
V_ASN1_OCTET_STRING, final_tag,
mac_len) == NULL) ? -1 : 1;
}
return 1;
}
int gost2015_acpkm_omac_init(int nid, int enc, const unsigned char *inkey,
EVP_MD_CTX *omac_ctx,
unsigned char *outkey, unsigned char *kdf_seed)
{
int ret = 0;
unsigned char keys[64];
const EVP_MD *md = EVP_get_digestbynid(nid);
EVP_PKEY *mac_key;
if (md == NULL)
return 0;
if (enc) {
if (RAND_bytes(kdf_seed, 8) != 1)
return 0;
}
if (gost_kdftree2012_256(keys, 64, inkey, 32,
(const unsigned char *)"kdf tree", 8, kdf_seed, 8, 1) <= 0)
return 0;
mac_key = EVP_PKEY_new_mac_key(nid, NULL, keys+32, 32);
if (mac_key == NULL)
goto end;
if (EVP_DigestInit_ex(omac_ctx, md, NULL) <= 0 ||
EVP_DigestSignInit(omac_ctx, NULL, md, NULL, mac_key) <= 0)
goto end;
memcpy(outkey, keys, 32);
ret = 1;
end:
EVP_PKEY_free(mac_key);
OPENSSL_cleanse(keys, sizeof(keys));
return ret;
}
int init_zero_kdf_seed(unsigned char *kdf_seed)
{
int is_zero_kdfseed = 1, i;
for (i = 0; i < 8; i++) {
if (kdf_seed[i] != 0)
is_zero_kdfseed = 0;
}
return is_zero_kdfseed ? RAND_bytes(kdf_seed, 8) : 1;
}
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