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Diffstat (limited to 'lib/decoding/osmocom/gsm/a5.h')
-rw-r--r-- | lib/decoding/osmocom/gsm/a5.h | 55 |
1 files changed, 55 insertions, 0 deletions
diff --git a/lib/decoding/osmocom/gsm/a5.h b/lib/decoding/osmocom/gsm/a5.h new file mode 100644 index 0000000..fa63246 --- /dev/null +++ b/lib/decoding/osmocom/gsm/a5.h @@ -0,0 +1,55 @@ +/* + * Copyright (C) 2011 Sylvain Munaut <tnt@246tNt.com> + * + * 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. + */ + +#pragma once + +#include <stdint.h> + +#include <osmocom/core/defs.h> +#include <osmocom/core/bits.h> + +/*! \defgroup a5 GSM A5 ciphering algorithm + * @{ + * \file a5.h */ + +/*! Converts a frame number into the 22 bit number used in A5/x + * \param[in] fn The true framenumber + * \return 22 bit word + */ +static inline uint32_t +osmo_a5_fn_count(uint32_t fn) +{ + int t1 = fn / (26 * 51); + int t2 = fn % 26; + int t3 = fn % 51; + return (t1 << 11) | (t3 << 5) | t2; +} + + /* Notes: + * - key must be 8 or 16 (for a5/4) bytes long (or NULL for A5/0) + * - the dl and ul pointer must be either NULL or 114 bits long + * - fn is the _real_ GSM frame number. + * (converted internally to fn_count) + */ +int osmo_a5(int n, const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul); +void osmo_a5_1(const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul) OSMO_DEPRECATED("Use generic osmo_a5() instead"); +void osmo_a5_2(const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul) OSMO_DEPRECATED("Use generic osmo_a5() instead"); + +/*! @} */ |