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/*
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Miroslav Lichvar 2019, 2022
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
**********************************************************************
=======================================================================
SIV ciphers using the Nettle library
*/
#include "config.h"
#include "sysincl.h"
#include <nettle/siv-cmac.h>
#ifdef HAVE_NETTLE_SIV_GCM
#include <nettle/siv-gcm.h>
#endif
#include "memory.h"
#include "siv.h"
#include "util.h"
struct SIV_Instance_Record {
SIV_Algorithm algorithm;
int key_set;
int min_nonce_length;
int max_nonce_length;
int tag_length;
union {
struct siv_cmac_aes128_ctx cmac_aes128;
#ifdef HAVE_NETTLE_SIV_GCM
struct aes128_ctx aes128;
#endif
} ctx;
};
/* ================================================== */
SIV_Instance
SIV_CreateInstance(SIV_Algorithm algorithm)
{
SIV_Instance instance;
if (SIV_GetKeyLength(algorithm) <= 0)
return NULL;
instance = MallocNew(struct SIV_Instance_Record);
instance->algorithm = algorithm;
instance->key_set = 0;
switch (algorithm) {
case AEAD_AES_SIV_CMAC_256:
instance->min_nonce_length = SIV_MIN_NONCE_SIZE;
instance->max_nonce_length = INT_MAX;
instance->tag_length = SIV_DIGEST_SIZE;
break;
#ifdef HAVE_NETTLE_SIV_GCM
case AEAD_AES_128_GCM_SIV:
instance->min_nonce_length = SIV_GCM_NONCE_SIZE;
instance->max_nonce_length = SIV_GCM_NONCE_SIZE;
instance->tag_length = SIV_GCM_DIGEST_SIZE;
break;
#endif
default:
assert(0);
}
return instance;
}
/* ================================================== */
void
SIV_DestroyInstance(SIV_Instance instance)
{
Free(instance);
}
/* ================================================== */
int
SIV_GetKeyLength(SIV_Algorithm algorithm)
{
assert(2 * AES128_KEY_SIZE <= SIV_MAX_KEY_LENGTH);
switch (algorithm) {
case AEAD_AES_SIV_CMAC_256:
return 2 * AES128_KEY_SIZE;
#ifdef HAVE_NETTLE_SIV_GCM
case AEAD_AES_128_GCM_SIV:
return AES128_KEY_SIZE;
#endif
default:
return 0;
}
}
/* ================================================== */
int
SIV_SetKey(SIV_Instance instance, const unsigned char *key, int length)
{
if (length != SIV_GetKeyLength(instance->algorithm))
return 0;
switch (instance->algorithm) {
case AEAD_AES_SIV_CMAC_256:
siv_cmac_aes128_set_key(&instance->ctx.cmac_aes128, key);
break;
#ifdef HAVE_NETTLE_SIV_GCM
case AEAD_AES_128_GCM_SIV:
aes128_set_encrypt_key(&instance->ctx.aes128, key);
break;
#endif
default:
assert(0);
}
instance->key_set = 1;
return 1;
}
/* ================================================== */
int
SIV_GetMinNonceLength(SIV_Instance instance)
{
return instance->min_nonce_length;
}
/* ================================================== */
int
SIV_GetMaxNonceLength(SIV_Instance instance)
{
return instance->max_nonce_length;
}
/* ================================================== */
int
SIV_GetTagLength(SIV_Instance instance)
{
BRIEF_ASSERT(instance->tag_length >= 1 && instance->tag_length <= SIV_MAX_TAG_LENGTH);
return instance->tag_length;
}
/* ================================================== */
int
SIV_Encrypt(SIV_Instance instance,
const unsigned char *nonce, int nonce_length,
const void *assoc, int assoc_length,
const void *plaintext, int plaintext_length,
unsigned char *ciphertext, int ciphertext_length)
{
if (!instance->key_set)
return 0;
if (nonce_length < instance->min_nonce_length ||
nonce_length > instance->max_nonce_length || assoc_length < 0 ||
plaintext_length < 0 || plaintext_length > ciphertext_length ||
plaintext_length + SIV_GetTagLength(instance) != ciphertext_length)
return 0;
assert(assoc && plaintext);
switch (instance->algorithm) {
case AEAD_AES_SIV_CMAC_256:
siv_cmac_aes128_encrypt_message(&instance->ctx.cmac_aes128,
nonce_length, nonce, assoc_length, assoc,
ciphertext_length, ciphertext, plaintext);
break;
#ifdef HAVE_NETTLE_SIV_GCM
case AEAD_AES_128_GCM_SIV:
siv_gcm_aes128_encrypt_message(&instance->ctx.aes128,
nonce_length, nonce, assoc_length, assoc,
ciphertext_length, ciphertext, plaintext);
break;
#endif
default:
assert(0);
}
return 1;
}
/* ================================================== */
int
SIV_Decrypt(SIV_Instance instance,
const unsigned char *nonce, int nonce_length,
const void *assoc, int assoc_length,
const unsigned char *ciphertext, int ciphertext_length,
void *plaintext, int plaintext_length)
{
if (!instance->key_set)
return 0;
if (nonce_length < instance->min_nonce_length ||
nonce_length > instance->max_nonce_length || assoc_length < 0 ||
plaintext_length < 0 || plaintext_length > ciphertext_length ||
plaintext_length + SIV_GetTagLength(instance) != ciphertext_length)
return 0;
assert(assoc && plaintext);
switch (instance->algorithm) {
case AEAD_AES_SIV_CMAC_256:
if (!siv_cmac_aes128_decrypt_message(&instance->ctx.cmac_aes128,
nonce_length, nonce, assoc_length, assoc,
plaintext_length, plaintext, ciphertext))
return 0;
break;
#ifdef HAVE_NETTLE_SIV_GCM
case AEAD_AES_128_GCM_SIV:
if (!siv_gcm_aes128_decrypt_message(&instance->ctx.aes128,
nonce_length, nonce, assoc_length, assoc,
plaintext_length, plaintext, ciphertext))
return 0;
break;
#endif
default:
assert(0);
}
return 1;
}
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