轻量级可调分组密码QARMA的不可能差分攻击

Impossible Differential Attack on Lightweight Tweakable Block Cipher

QARMA是一种轻量级可调分组密码.本文使用不可能差分攻击对QARMA算法进行了分析.据我们所知,这是首次使用不可能差分攻击来分析该算法.我们提出了一个5轮的不可能差分区分器,包含了仿反射结构以及它前面的两轮和后面的三轮.通过在不可能差分区分器的前面加两轮,后面加三轮,我们对10轮的QARMA进行了攻击.另外,我们通过使用另一个不可能差分路径来进一步降低了密钥恢复的时间复杂度.我们的攻击的数据复杂度为261.9个明文,时间复杂度为265.8次10轮加密,存储复杂度为258.6个64比特序列.与现有的中间相遇攻击相比,我们的方法在时间复杂度和存储复杂度上有较大优势.

QARMA is a lightweight tweakable block cipher.In this paper,we use impossible differential attack to analyze QARMA.To our knowledge,this is the first time to analyze QARMA by using impossible differential attack.We give the first impossible differential distinguisher of QARMA block cipher.It is made up of the Pseudo-Reflector construction with two forward rounds and the three backward rounds.By adding two rounds on the top and three rounds on the bottom of the distinguisher,we achieve a 10-round key recovery attack.In addition,we put forward a method of using two distinguisher in order to reduce the time complexity.The data complexity is 2（61.9） chosen plaintexts,the time complexity is 2（65.8） encryption units and the memory complexity is 2（58.6） 64-bit space.Compared with the previous known Meet-in-the-Middle attack,our attack reduces the time complexity and memory complexity.