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/*
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Miroslav Lichvar 2021
*
* 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.
*
**********************************************************************
=======================================================================
CMAC using the GnuTLS library
*/
#include "config.h"
#include "sysincl.h"
#include <gnutls/crypto.h>
#include "cmac.h"
#include "hash.h"
#include "logging.h"
#include "memory.h"
struct CMC_Instance_Record {
gnutls_mac_algorithm_t algorithm;
gnutls_hmac_hd_t mac;
};
/* ================================================== */
static int instance_counter = 0;
static int gnutls_initialised = 0;
/* ================================================== */
static void
init_gnutls(void)
{
int r;
if (gnutls_initialised)
return;
r = gnutls_global_init();
if (r < 0)
LOG_FATAL("Could not initialise %s : %s", "gnutls", gnutls_strerror(r));
DEBUG_LOG("Initialised");
gnutls_initialised = 1;
}
/* ================================================== */
static void
deinit_gnutls(void)
{
assert(gnutls_initialised);
gnutls_global_deinit();
gnutls_initialised = 0;
DEBUG_LOG("Deinitialised");
}
/* ================================================== */
static gnutls_mac_algorithm_t
get_mac_algorithm(CMC_Algorithm algorithm)
{
switch (algorithm) {
case CMC_AES128:
return GNUTLS_MAC_AES_CMAC_128;
case CMC_AES256:
return GNUTLS_MAC_AES_CMAC_256;
default:
return GNUTLS_MAC_UNKNOWN;
}
}
/* ================================================== */
int
CMC_GetKeyLength(CMC_Algorithm algorithm)
{
gnutls_mac_algorithm_t malgo = get_mac_algorithm(algorithm);
int len;
if (malgo == GNUTLS_MAC_UNKNOWN)
return 0;
len = gnutls_hmac_get_key_size(malgo);
if (len < 0)
return 0;
return len;
}
/* ================================================== */
CMC_Instance
CMC_CreateInstance(CMC_Algorithm algorithm, const unsigned char *key, int length)
{
gnutls_hmac_hd_t handle;
CMC_Instance inst;
int r;
if (instance_counter == 0)
init_gnutls();
if (length <= 0 || length != CMC_GetKeyLength(algorithm))
goto error;
r = gnutls_hmac_init(&handle, get_mac_algorithm(algorithm), key, length);
if (r < 0) {
DEBUG_LOG("Could not initialise %s : %s", "mac", gnutls_strerror(r));
goto error;
}
inst = MallocNew(struct CMC_Instance_Record);
inst->algorithm = get_mac_algorithm(algorithm);
inst->mac = handle;
instance_counter++;
return inst;
error:
if (instance_counter == 0)
deinit_gnutls();
return NULL;
}
/* ================================================== */
int
CMC_Hash(CMC_Instance inst, const void *in, int in_len, unsigned char *out, int out_len)
{
unsigned char buf[MAX_HASH_LENGTH];
int hash_len;
if (in_len < 0 || out_len < 0)
return 0;
hash_len = gnutls_hmac_get_len(inst->algorithm);
if (out_len > hash_len)
out_len = hash_len;
if (hash_len > sizeof (buf))
return 0;
if (gnutls_hmac(inst->mac, in, in_len) < 0) {
/* Reset the state */
gnutls_hmac_output(inst->mac, buf);
return 0;
}
gnutls_hmac_output(inst->mac, buf);
memcpy(out, buf, out_len);
return out_len;
}
/* ================================================== */
void
CMC_DestroyInstance(CMC_Instance inst)
{
gnutls_hmac_deinit(inst->mac, NULL);
Free(inst);
instance_counter--;
if (instance_counter == 0)
deinit_gnutls();
}
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