Conditional and unconditional correlation weaknesses of cascades of up/down clocked shift registers are determined. The corresponding
systematic correlation attacks are proposed and the conditions for their success are obtained.
Keywords Stream ciphers - clock-controlled shift registers - up/down and stop/go cascades - cryptanalysis - correlation attacks
This work was done while the first author was with the Information Security Research Centre, Queensland University of Technology,
Brisbane, Australia. Part of this work was carried out while the first author was on leave at the Isaac Newton Institute for
Mathematical Sciences, Cambridge, United Kingdom.