keysetup_reverse.c File Reference

Implementation of last attack phase on A5/2: keysetup reversal. More...

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include "utils.h"
#include "keysetup_reverse.h"

Data Structures
struct	keysetup_reverse_LFSRSet_t
	Set of all LFSR's variables. More...
Typedefs
typedef keysetup_reverse_LFSRSet_t *	keysetup_reverse_LFSRSet
	Pointer to a set of LFSR's variables.
Functions
void	keysetup_reverse_clockRegs (keysetup_reverse_LFSRSet LFSRs)
	Clock all registers (during the keysetup phase, the clocking unit is unused).
int	reverseKeysetup (const byte R1[R1_BITS], const byte R2[R2_BITS], const byte R3[R3_BITS], const byte R4[R4_BITS], const byte frameId[FRAMEID_BITS], byte secretKey[SECRETKEY_BITS])
	Performs the reversal of the keysetup, retrieving the Secret Key from the LFSRs state after keysetup.
int	keysetup_reverse_test ()
	Autotests the reversal of the keysetup on a verified set of problem/solution.

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Detailed Description

Implementation of last attack phase on A5/2: keysetup reversal.

Author:

Nicolas Paglieri & Olivier Benjamin

Version:

File Revision #8

Date:

24/06/2011

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Function Documentation

void keysetup_reverse_clockRegs

(

keysetup_reverse_LFSRSet

LFSRs

)

Clock all registers (during the keysetup phase, the clocking unit is unused).

Parameters:

[in,out]

LFSRs

Pointer to the set of LFSR's variables to clock

References keysetup_reverse_LFSRSet_t::R1, R1_BITS, keysetup_reverse_LFSRSet_t::R2, R2_BITS, keysetup_reverse_LFSRSet_t::R3, R3_BITS, keysetup_reverse_LFSRSet_t::R4, R4_BITS, SECRETKEY_BITS, and XOR_CHARARRAYS.

Referenced by reverseKeysetup().

int keysetup_reverse_test

(

)

Autotests the reversal of the keysetup on a verified set of problem/solution.

Returns:

0 if the test is successfull, non-zero otherwise

References DEBUG, DUMP_CHAR_VECTOR, FRAMEID_BITS, R1, R1_BITS, R2, R2_BITS, R3, R3_BITS, R4, R4_BITS, reverseKeysetup(), and SECRETKEY_BITS.

Referenced by main().

int reverseKeysetup	(	const byte	R1[R1_BITS],
		const byte	R2[R2_BITS],
		const byte	R3[R3_BITS],
		const byte	R4[R4_BITS],
		const byte	frameId[FRAMEID_BITS],
		byte	secretKey[SECRETKEY_BITS]
	)

Performs the reversal of the keysetup, retrieving the Secret Key from the LFSRs state after keysetup.

Parameters:

[in]	R1	Status of register R1 after keysetup
[in]	R2	Status of register R2 after keysetup
[in]	R3	Status of register R3 after keysetup
[in]	R4	Status of register R4 after keysetup
[in]	frameId	Publicly known Frame Id
[out]	secretKey	Recovered secret key if the attack succeeded, all zeros otherwise

Returns:

0 if the reversal is successful, non-zero otherwise

References DEBUG, FRAMEID_BITS, keysetup_reverse_clockRegs(), R1, keysetup_reverse_LFSRSet_t::R1, R1_BITS, R2, keysetup_reverse_LFSRSet_t::R2, R2_BITS, R3, keysetup_reverse_LFSRSet_t::R3, R3_BITS, R4, keysetup_reverse_LFSRSet_t::R4, R4_BITS, REGS_BITS, SECRETKEY_BITS, and XOR_CHARARRAYS.

Referenced by attack_decipherSecretKey(), and keysetup_reverse_test().