Impossible differential attacks on reduced-round LBlock

Abstract

LBlock is a lightweight block cipher with 32 rounds, which can be implemented efficiently not only in hardware environment but also in software platforms. In this paper, by exploiting the structure of LBlock and the redundancy in its key schedule, we propose an impossible differential attack on 21-round LBlock based on a 14-round impossible differential. The data and time complexities are about 2 62.5 chosen plaintexts and 2 73.7 21-round encryptions, respectively. As far as we know, these results are the currently best results on LBlock in the single key scenario. © 2012 Springer-Verlag.