a5.c File Reference

Osmocom GSM A5 ciphering algorithm implementation. More...

#include <errno.h>
#include <string.h>
#include <stdbool.h>
#include <osmocom/gsm/a5.h>
#include <osmocom/gsm/kasumi.h>

Macros
#define	ENOTSUP   EINVAL
#define	A5_R1_LEN   19
#define	A5_R2_LEN   22
#define	A5_R3_LEN   23
#define	A5_R4_LEN   17 /* A5/2 only */
#define	A5_R1_MASK   ((1<<A5_R1_LEN)-1)
#define	A5_R2_MASK   ((1<<A5_R2_LEN)-1)
#define	A5_R3_MASK   ((1<<A5_R3_LEN)-1)
#define	A5_R4_MASK   ((1<<A5_R4_LEN)-1)
#define	A5_R1_TAPS   0x072000 /* x^19 + x^18 + x^17 + x^14 + 1 */
#define	A5_R2_TAPS   0x300000 /* x^22 + x^21 + 1 */
#define	A5_R3_TAPS   0x700080 /* x^23 + x^22 + x^21 + x^8 + 1 */
#define	A5_R4_TAPS   0x010800 /* x^17 + x^12 + 1 */
#define	A51_R1_CLKBIT   0x000100
#define	A51_R2_CLKBIT   0x000400
#define	A51_R3_CLKBIT   0x000400
#define	A52_R4_CLKBIT0   0x000400
#define	A52_R4_CLKBIT1   0x000008
#define	A52_R4_CLKBIT2   0x000080

Functions
void	_a5_4 (const uint8_t *ck, uint32_t fn, ubit_t *dl, ubit_t *ul, bool fn_correct)
	Generate a GSM A5/4 cipher stream. More...
void	_a5_3 (const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul, bool fn_correct)
	Generate a GSM A5/3 cipher stream. More...
int	osmo_a5 (int n, const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul)
	Main method to generate a A5/x cipher stream. More...
static uint32_t	_a5_12_parity (uint32_t x)
	Computes parity of a 32-bit word. More...
static uint32_t	_a5_12_majority (uint32_t v1, uint32_t v2, uint32_t v3)
	Compute majority bit from 3 taps. More...
static uint32_t	_a5_12_clock (uint32_t r, uint32_t mask, uint32_t taps)
	Compute the next LFSR state. More...
static void	_a5_1_clock (uint32_t r[], int force)
	GSM A5/1 Clocking function. More...
static uint8_t	_a5_1_get_output (uint32_t r[])
	GSM A5/1 Output function. More...
void	osmo_a5_1 (const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul)
	Generate a GSM A5/1 cipher stream. More...
static void	_a5_2_clock (uint32_t r[], int force)
	GSM A5/2 Clocking function. More...
static uint8_t	_a5_2_get_output (uint32_t r[])
	GSM A5/2 Output function. More...
void	osmo_a5_2 (const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul)
	Generate a GSM A5/1 cipher stream. More...

Detailed Description

Osmocom GSM A5 ciphering algorithm implementation.