Common library for all Osmocom projects (libosmocore, libosmogsm, libosmovty, libosmogb, libosmosim, libosmousb, ...) https://osmocom.org/projects/libosmocore
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libosmocore/src/gsm/gprs_cipher_core.c

99 lines
2.7 KiB

/* GPRS LLC cipher core infrastructure */
/* (C) 2010 by Harald Welte <laforge@gnumonks.org>
*
* All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* 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.
*
*/
#include <errno.h>
#include <stdint.h>
#include <osmocore/utils.h>
#include <osmocore/linuxlist.h>
#include <osmocore/plugin.h>
#include <osmocom/crypt/gprs_cipher.h>
static LLIST_HEAD(gprs_ciphers);
static struct gprs_cipher_impl *selected_ciphers[_GPRS_ALGO_NUM];
/* register a cipher with the core */
int gprs_cipher_register(struct gprs_cipher_impl *ciph)
{
if (ciph->algo > ARRAY_SIZE(selected_ciphers))
return -ERANGE;
llist_add_tail(&ciph->list, &gprs_ciphers);
/* check if we want to select this implementation over others */
if (!selected_ciphers[ciph->algo] ||
(selected_ciphers[ciph->algo]->priority > ciph->priority))
selected_ciphers[ciph->algo] = ciph;
return 0;
}
/* load all available GPRS cipher plugins */
int gprs_cipher_load(const char *path)
{
/* load all plugins available from path */
return plugin_load_all(path);
}
/* function to be called by core code */
int gprs_cipher_run(uint8_t *out, uint16_t len, enum gprs_ciph_algo algo,
uint64_t kc, uint32_t iv, enum gprs_cipher_direction dir)
{
if (algo > ARRAY_SIZE(selected_ciphers))
return -ERANGE;
if (!selected_ciphers[algo])
return -EINVAL;
if (len > GSM0464_CIPH_MAX_BLOCK)
return -ERANGE;
/* run the actual cipher from the plugin */
return selected_ciphers[algo]->run(out, len, kc, iv, dir);
}
int gprs_cipher_supported(enum gprs_ciph_algo algo)
{
if (algo > ARRAY_SIZE(selected_ciphers))
return -ERANGE;
if (selected_ciphers[algo])
return 1;
return 0;
}
/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
uint32_t gprs_cipher_gen_input_ui(uint32_t iov_ui, uint8_t sapi, uint32_t lfn, uint32_t oc)
{
uint32_t sx = ((1<<27) * sapi) + (1<<31);
return (iov_ui ^ sx) + lfn + oc;
}
/* GSM TS 04.64 / Section A.2.1 : Generation of 'input' */
uint32_t gprs_cipher_gen_input_i(uint32_t iov_i, uint32_t lfn, uint32_t oc)
{
return iov_i + lfn + oc;
}