SAFER++的差分分析  

Differential Analysis of SAFER++

作　　者：郑世慧[1] 王小云[1] 王美琴[1] 张国艳[1] 

机构地区：[1]山东大学数学与系统科学学院,济南250100

出　　处：《计算机工程与应用》2005年第30期21-23,共3页Computer Engineering and Applications

基　　金：国家自然科学基金资助项目(编号:90304009)

摘　　要：SAFER++是欧洲信息工程的参选算法,并且是进入第2轮的7个候选算法之一。算法的设计者称5轮SAFER++算法可以抵抗差分分析。本文利用异或差分与模减差分串连得到3.75轮的高概率特征,对4轮SAFER++进行选择明文攻击。攻击过程的计算复杂度约为298.2次加密运算,数据复杂度是296,可以恢复出12字节的密钥。而且如果存在4轮特征(设计者称已经通过搜索的方法找到),可以利用本文提出的方法得到更高轮数的特征,用于攻击5轮以上的SAFER++算法。SAFER＋＋ is submitted to the European pre-standardization project NESSIE and is one of the seven primitives-selected for the second phase of this project.The designers claim that 5-round SAFER＋＋ is secure against differential cryptanalysis.ln this paper we obtain a high probability characteristic of 3.75-round based on the concatenation of XOR-differential and minus-modulo-256-differential.It can be used in the chosen plaintext attack of 4-round SAFER＋＋ and recover 12 bytes keys.The computation complexity is 2^98.2 and the data complexity is 2^96.Furthermore,if there is a suitable 4-round characteristic（the designer had found）,the method we proposed can obtain good characteristics to attack SAFER＋＋ with at least 5-round.

关 键 词：密码分析 SAFER++ 差分分析 

分 类 号：TP309[自动化与计算机技术—计算机系统结构]