E2算法的中间相遇攻击

Meet-in-the-middle attacks on E2

作为AES的候选算法,E2算法由于其特殊的两层SP结构一直是人们研究的热点。研究了E2算法抵抗中间相遇攻击的能力。基于E2算法的结构,利用中间相遇的思想设计了一个4轮区分器,利用该区分器,对E2算法进行了5轮、6轮中间相遇攻击。研究结果表明,E2-128算法对于5轮中间相遇攻击以及E2-256算法对于6轮中间相遇攻击是不抵抗的。这是首次用中间相遇的攻击方法对E2算法进行的分析,相对于已有的结果,该方法降低了所用数据复杂度。

As a candidate of AES,E2 algorithm has attracted wide attention because of its unique two SP structures.We evaluate the security of E2 block cipher against meet-in-the-middle attacks.Based on the idea of meet-in-the-middle,by analyzing the feathers of E2 algorithm,a 4-round distinguisher is designed.Using the distinguisher,some meet-in-the-middle attacks are made on 5/6-round E2-128/256.It is shown that the E2-128 algorithm to 5-round and the E2-256 algorithm to 6-round are not immune to meet-in-the-middle attacks.This is the first time to use the meet-in-the-middle attacks to analyze the E2 algorithm.Compared with the existing results,data complexity is reduced.