用不可能差分法分析12轮ESF算法

摘要

ESF is a lightweight block cipher algorithm with generalized Feistel structure of 32 rounds of iterated block ciphers.Its round function employs SPN structure.The block size of ESF is 64-bit and the key size is 80-bit.In order to analyze impossible differential cryptanalysis on the block cipher ESF,based on one 8-round impossible differential route,according to the relationship of the round keys,through adding two rounds in the front and adding two rounds in the end,12-round ESF was attacked.Computing result shows that the attacks of 12-round ESF need O(253) data complexity,and O(260.43) time complexity,so 12-round ESF is not immune to impossible differential cryptanalysis.%轻量级分组密码算法ESF是一种具有广义Feistel结构的32轮迭代型分组密码,轮函数具有SPN结构,分组长度为64比特,密钥长度为80比特.为了研究ESF算法抵抗不可能差分攻击的能力,基于一条8轮不可能差分路径,根据轮密钥之间的关系,通过向前增加2轮、向后增加2轮的方式,对12轮ESF算法进行了攻击.计算结果表明,攻击12轮ESF算法所需的数据复杂度为O(253),时间复杂度为O(260.43),由此说明12轮的ESF算法对不可能差分密码分析是不免疫的.