WCSE

Improved State-Recovery Attacks on Modified KETJE JR

Abstract— KETJE, a lightweight authenticated encryption cipher is a third-round candidate of CAESAR competition whose design principles are similar to SHA-3 hash function. Fuhr et al. studied the security of KETJE JR against divide-and-conquer attacks and proposed state-recovery attacks on modified KETJE JR. In this paper, we study the relations among the algebraic representations of internal state bits, and find new guessing strategies based on Fuhr et al.'s method. With the usage of new guessing strategies, we improve the state-recovery attacks on KETJE JR v1 when r=40 and r=32. Compared with Fuhr et al.'s work, our results are more efficient. The relults do not threaten the security of KETJE in practice, but provide evidence for improving the efficiency of KETJE by increasing the rate

Index Terms— lightweight authenticated encryption cipher, cryptanalysis, KETJE JR, state-recovery attack, divide-and-conquer attack

Guo-Shuang Zhang
Institute of Information Engineering, Chinese Academy of Sciences, CHINA
School of Cyber Security, University of Chinese Academy of Sciences, CHINA
Yin Li
Dongguan University of Technology, CHINA
Xiao Chen
Institute of Information Engineering, Chinese Academy of Sciences, CHINA
School of Cyber Security, University of Chinese Academy of Sciences, CHINA

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Cite: Guo-Shuang Zhang, Yin Li, Xiao Chen , "Improved State-Recovery Attacks on Modified KETJE JR ," 2021 The 11th International Workshop on Computer Science and Engineering (WCSE 2021), pp. 265-275, Shanghai, China, June 19-21, 2021.