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Diffstat (limited to '')
| -rw-r--r-- | cmac_gnutls.c | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/cmac_gnutls.c b/cmac_gnutls.c new file mode 100644 index 0000000..d1cd550 --- /dev/null +++ b/cmac_gnutls.c @@ -0,0 +1,189 @@ +/* + 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(); +} |