对简化轮数的Crypton算法的中间相遇攻击

A Meet-in-the-Middle Attack on Reduced-Round Crypton

摘要:

Crypton算法是一种SPN型分组密码，它是分组长度为128 bit的AES候选算法之一。本文借助于多重集的概念，评估了简化轮数的Crypton算法对中间相遇攻击的抵抗能力，设计出两类4/5轮区分器，对7/8/9轮的Crypton算法实施了攻击。所有的攻击实例都给出了复杂度分析，攻击结果表明9轮的Crypton算法对中间相遇攻击是不免疫的，而且新攻击有效地降低了攻击所需的数据复杂度。

Abstract: Crypton, one of AES candidates, is a 128 bit block cipher of SPN structure proposed by Lim. By means of the concept of Multiset, this paper evaluates the security of the reduced-round Crypton against meet-in-the-middle at- tack, constructs two categories of distinguishers of 4/5 round used to the attack on Crypton algorithm of 7/8/9round. All the attack instances give the complexity analysis. The results demonstrate that Crypton reduced to 9 rounds is not im- mune to meet-in-the-middle attacks, and new attacks reduced the data complexity efficiently.