Sylvain Munaut | f1d3344 | 2011-04-23 15:34:11 +0200 | [diff] [blame] | 1 | /* |
| 2 | * a5.h |
| 3 | * |
| 4 | * Copyright (C) 2011 Sylvain Munaut <tnt@246tNt.com> |
| 5 | * |
| 6 | * All Rights Reserved |
| 7 | * |
| 8 | * This program is free software; you can redistribute it and/or modify |
| 9 | * it under the terms of the GNU General Public License as published by |
| 10 | * the Free Software Foundation; either version 2 of the License, or |
| 11 | * (at your option) any later version. |
| 12 | * |
| 13 | * This program is distributed in the hope that it will be useful, |
| 14 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | * GNU General Public License for more details. |
| 17 | * |
| 18 | * You should have received a copy of the GNU General Public License along |
| 19 | * with this program; if not, write to the Free Software Foundation, Inc., |
| 20 | * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. |
| 21 | */ |
| 22 | |
| 23 | #ifndef __OSMO_A5_H__ |
| 24 | #define __OSMO_A5_H__ |
| 25 | |
| 26 | #include <stdint.h> |
| 27 | |
| 28 | #include <osmocom/core/bits.h> |
| 29 | |
Sylvain Munaut | 2735ac4 | 2011-11-17 21:01:46 +0100 | [diff] [blame] | 30 | /*! \defgroup a5 GSM A5 ciphering algorithm |
| 31 | * @{ |
| 32 | */ |
| 33 | |
| 34 | /*! \file gsm/a5.h |
| 35 | * \brief Osmocom GSM A5 ciphering algorithm header |
| 36 | */ |
| 37 | |
| 38 | /*! \brief Converts a frame number into the 22 bit number used in A5/x |
| 39 | * \param[in] fn The true framenumber |
| 40 | * \return 22 bit word |
| 41 | */ |
Sylvain Munaut | f1d3344 | 2011-04-23 15:34:11 +0200 | [diff] [blame] | 42 | static inline uint32_t |
| 43 | osmo_a5_fn_count(uint32_t fn) |
| 44 | { |
| 45 | int t1 = fn / (26 * 51); |
| 46 | int t2 = fn % 26; |
| 47 | int t3 = fn % 51; |
| 48 | return (t1 << 11) | (t3 << 5) | t2; |
| 49 | } |
| 50 | |
| 51 | /* Notes: |
| 52 | * - key must be 8 bytes long (or NULL for A5/0) |
| 53 | * - the dl and ul pointer must be either NULL or 114 bits long |
| 54 | * - fn is the _real_ GSM frame number. |
| 55 | * (converted internally to fn_count) |
| 56 | */ |
Sylvain Munaut | c1e9be9 | 2012-12-06 08:23:02 +0100 | [diff] [blame] | 57 | int osmo_a5(int n, const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul); |
Sylvain Munaut | 3e387cb | 2011-11-17 19:45:42 +0100 | [diff] [blame] | 58 | void osmo_a5_1(const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul); |
| 59 | void osmo_a5_2(const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul); |
Sylvain Munaut | f1d3344 | 2011-04-23 15:34:11 +0200 | [diff] [blame] | 60 | |
Sylvain Munaut | dca7d2c | 2012-04-18 21:53:23 +0200 | [diff] [blame] | 61 | /*! @} */ |
Sylvain Munaut | 2735ac4 | 2011-11-17 21:01:46 +0100 | [diff] [blame] | 62 | |
Sylvain Munaut | f1d3344 | 2011-04-23 15:34:11 +0200 | [diff] [blame] | 63 | #endif /* __OSMO_A5_H__ */ |