An improved attack on clock-controlled shift registers based on hardware implementation

作者：Li Lei^*; Liu XiangHui; Wang Zheng; Li FengHua

来源：Science China Information Sciences, 2013, 56(11): 112107.

DOI：10.1007/s11432-012-4682-8

• stop/go clocking
• A5/1
• state space convergence
• SMITH
• special-purpose hardware

We cryptanalyze a type of stream generator with three linear-feedback shift registers that are mutually clocked in a stop/go manner and have the property of sequences of state space convergence. By guessing the clock-controlled sequence and employing a backtracking search, we propose an algorithm attack on the type of stream generator based on hardware implementation. In particular, the time complexity of the algorithm attacking the encryption algorithm A5/1 is 2(43.869) clock periods. With our hardware architecture, we investigate the implementation of the algorithm on field programmable gate array and application-specific integrated circuit for an attack on A5/1. As a result, we can retrieve the initial states of A5/1's registers in 2 s on average without pre-computation if we have 64 known key-stream bits.

• 出版日期2013-11
• 单位中国科学院信息工程研究所; 中国科学技术信息研究所