SHACAL-2算法的研究与改进  

Research and improvement of SHACAL-2 algorithm

作　　者：时阳阳[1] 黄玉划[1] 陈帮春[1] 

机构地区：[1]南京航空航天大学计算机科学与技术学院,南京210016

出　　处：《计算机应用研究》2013年第8期2520-2522,2526,共4页Application Research of Computers

基　　金：航空科学基金资助项目(20081952014;20085552021);区域光纤通信网与新型光通信系统国家重点实验室开放课题(2008SH06);南京航空航天大学基本科研业务费专项科研资助项目(NS2010097)

摘　　要：SHACAL-2是2003年当选的四个欧洲分组密码标准算法中分组长度和密钥长度均为最长的算法。为了加快SHACAL-2扩散和混乱,对其算法进行两方面的修改:一方面修改密钥扩展函数,可以避免初始密钥在全为0而扩展后依旧全为0,并且提高了加密的效率;另一方面修改迭代函数,使得上一轮的所有消息分组能同时影响到下一轮的两个消息分组。依赖性测试表明,改进后算法比改进前提前1轮开始满足完备性、雪崩效应和严格雪崩准则;模差分攻击分析表明,该算法的18步差分攻击的时间复杂度由O(214)提高到O(227)。改进方案提高了算法的效率和安全性。SHACAL-2 has the longest block length and biggest key size among the four standard block ciphers selected by New European schemes for signatures, integrity and encryption in 2003. In order to accelerate the diffusion and confusion of SHACAL- 2,this paper modified two aspects of the algorithm. On one hand, making a modification on the key extension function,which could result the keys still in 0 after expansion of the initial keys with 0, and improved the encryption efficiency. On the other hand,making a modification on iterative function, which could make all news groups in former round influence the two ones in the next group. Dependence test shows that the improved algorithm advances one round than premise to meet the completeness, the avalanche effect and the strict avalanche criteria. Differential attack presents that time complexity in the 18 steps of this algorithm improves from O（2 14） to O（2 27）. The improved programme advances the efficiency and safety of the algorithm.

关 键 词：SHACAL-2 迭代函数 密钥扩展 依赖性测试 模差分攻击 

分 类 号：TN918.1[电子电信—通信与信息系统]