Decimation Attack of Stream Ciphers

This paper presents a new attack called Decimation Attack of most stream ciphers. It exploits the property that multiple clocking (or equivalently d-th decimation) of a LFSR can simulate the behavior of many other LFSRs of possible shorter length. It yields then signiicant improvements of all the previous known correlation and fast correlation attacks. A new criterion on the length of the polynomial is then deened to resist to the decimation attack. Simulation results and complexity comparison are detailed for ciphertext only attacks.