Improved related-key differential attacks on reduced-round lblock

Abstract

At ACNS 2011, Wu and Zhang proposed a new lightweight block cipher which is named LBlock. The design rationale of LBlock considers the trade-offs between security against cryptanalyses and performance in low-resource implementations. In this paper, we present new attacks on reduced-round LBlock using related-key differential cryptanalysis. Firstly, we construct a new related-key boomerang distinguishing attack on 16-round LBlock. Secondly, we construct a key recovery attack on 22-round LBlock based on a 16-round related-key truncated differential. In contrast to the published cryptanalysis results of reduced-round LBlock, our attacks have advantages on data and computational complexities. © 2012 Springer-Verlag.