Biclique cryptanalysis on Midori block cipher

摘要

Biclique cryptanalysis is a typical key-recovery attack can significantly decrease computation and data complexity by utilising the main idea of meet-in-the-middle attack and the principle of biclique structure. In this paper, we first demonstrate the block cipher Midori64/128 and present a general method of biclique attack. Next, we describe the steps in constructing a biclique and attacking a full-round Midori block cipher. By investigating a simple key schedule, we present a full-round biclique cryptanalysis of Midori. Then, we construct a five-round biclique structure of four-dimensional and a four-round biclique structure for Midori64, with data complexity of 2~(36)and 2~(16)and computational complexity of 2~(126.45)and 2~(126.69), respectively. Moreover, we use a four-round biclique structure to attack Midori128 with data complexity of 2~(72)and computational complexity of 2~(127.01). These findings are superior to current results.