1 files changed, 63 insertions, 0 deletions
diff --git a/src/shared/libosmocore/include/osmocom/gsm/a5.h b/src/shared/libosmocore/include/osmocom/gsm/a5.h
new file mode 100644
index 00000000..649dbab1
--- /dev/null
+++ b/src/shared/libosmocore/include/osmocom/gsm/a5.h
@@ -0,0 +1,63 @@
+/*
+ * a5.h
+ *
+ * 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.
+ */
+
+#ifndef __OSMO_A5_H__
+#define __OSMO_A5_H__
+
+#include <stdint.h>
+
+#include <osmocom/core/bits.h>
+
+/*! \defgroup a5 GSM A5 ciphering algorithm
+ *  @{
+ */
+
+/*! \file gsm/a5.h
+ *  \brief Osmocom GSM A5 ciphering algorithm header
+ */
+
+/*! \brief 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 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)
+	 */
+void 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);
+void osmo_a5_2(const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul);
+
+/*! @} */
+
+#endif /* __OSMO_A5_H__ */