Rijndael算法优化技术研究
刘丽1,2, 何加铭1,2 , 刘太君1,2, 曾兴斌1,2
(1宁波大学 通信技术研究所,浙江 宁波 315211;2.宁波市通信芯片与射频技术重点实验室,浙江 宁波 315040)
摘 要:用于保护21世纪敏感信息的AES(Advanced Encryption Standard)算法的安全性一直是研究的热点.本文通过深入分析Rijndael算法,改进了算法的几个有可能产生不安全隐患的步骤,首先是对于最可能被攻击的混列(MixColumns)进行的优化,使该步骤变成简单的查表而不是域乘,增加了非线形安全性;而对于子密钥的生成方面我们引入了随机函数使密钥的生成和选择变成随机性的,而不是原算法简单的线形选择,这样就几乎可以完全抵抗线形密码分析的攻击了.
关键字:Rijndael算法;密钥;AES;S-盒
中图分类号:TP39 文献标识码:A
Research on the optimization of Rijndael Algorithm
Liu Li1, HE Jia-ming1,2, Liu Tai-jun1,2, Zeng Xing-bin1,2
(1 Communication Technology Institute, Ningbo University, 315211, China;
2. The Ningbo Key Lab of Communication Chips & RF Technology, 315040, China)
Abstract: The security of the AES protecting the sensitive information in 21the century is always the focus of research. Through analyzing the algorithm of Rijndael thoroughly, this thesis improves several steps inhering insecurity. By optimizing the MixColumns which tends to be attracted most probably, the thesis transforms the step from the multiplication in field to looking up tables so as to increase the security of nonlinearity. In the aspect of sub-key, comparing with the simple linear selection in the original algorithm, this paper brings in the random function to generate and choose the keys randomly so that the attract of linear cryptanalysis can be resisted almost totally.
Key Words: Rijndael algorithm, cryptographic key, AES, S-box
CLC number: TP39 Document Code: A
1. 引言
1997年4月15日美国国家标准技术研究所(NIST)发起征集AES(Advanced Encryption Standard) 算法的活动,并专门成立了AES工作组.目的是为了确定一个非保密的,公开披露的,全球免费使用的分组密码算法,用于保护21世纪政府的敏感信息.1997年9月12日在联邦登记处(FR)公布了征集AES候选算法的通告.AES的要求是比三重DES快而且至少和三重DES一样安全,分组长度为128比特,密钥长度为128,192,256比特.后来,NIST从15个算法中筛选出了5个AES候选算法,它们是RC6,Mars,Rijndael,Serpent和Twofish.最终,由比利时设计者Joan Daemen和Vincent Rijmen设计的Rijndael算法胜出.
2. 算法实现
2.1 加密解密过程
Rijndael加密算法是分组长度可变,密钥长度也可变的分组密码.分组长度,密钥长度彼此独立地确定为128,192,256比特.
2.1.1 字节转换(SubBytes)

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