Design and study of a strong crypto-system model for e-Commerce
ICCC '02 Proceedings of the 15th international conference on Computer communication
On the efficiency of the clock control guessing attack
ICISC'02 Proceedings of the 5th international conference on Information security and cryptology
State convergence in the initialisation of stream ciphers
ACISP'11 Proceedings of the 16th Australasian conference on Information security and privacy
A near-practical attack against b mode of HBB
ASIACRYPT'05 Proceedings of the 11th international conference on Theory and Application of Cryptology and Information Security
Slid pairs in the initialisation of the A5/1 stream cipher
AISC '13 Proceedings of the Eleventh Australasian Information Security Conference - Volume 138
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A binary stream cipher consisting of three short linear-feedback shift registers (LFSRs) of total length 64 that are mutually clocked in the stop/go manner is cryptanalyzed in the known keystream sequence scenario. To reconstruct the internal state candidates at a known time from about 64 known keystream bits, two algorithms are developed. One is based on guessing a number of elements of the clock-control sequence and has a computational complexity of about 240 steps, where the average step complexity is comparable to the step complexity of the exhaustive search method. The other exploits a time-memory tradeoff based on the well-known birthday paradox and is successful if approximately T·M⩾264, where T is the required computational time in table lookups and M is the memory in 64-bit words. As the state-transition function is not one-to-one, to recover the initial state from the internal state candidates, two algorithms are introduced. One consists in guessing the number of clocks for each of the LFSRs. The other consists in the reversion of the internal states and is based on the theory of critical and subcritical branching processes