论文标题:分组密码的分析与设计
Analysis and Design of Block Ciphers
论文作者 张文涛
论文导师 卿斯汉,论文学位 博士,论文专业 计算机应用技术
论文单位 中国科学院研究生院（软件研究所）,点击次数 150,论文页数 109页File Size4541k
2003-11-01论文网 http://www.lw23.com/lunwen_1688512/ 分组密码,安全性分析,可证明安全性,分组密码的设计,基于混沌函数的分组密码,基于细胞自动机的分组密码
Block Ciphers;Security Analysis;Provable security;Design of Block ciphers;Block Cipher based on Chaotic Maps;Block Cipher based on Cellular Automata
现代密码学理论和密码技术是信息安全的重要基础。分组密码是密码学的一个重要分支，它具有速度快、易于标准化和便于软硬件实现等特点，通常是信息与网络安全中实现数据加密、数字签名、认证及密钥管理的核心体制。 随着AES活动的开展，分组密码成为近几年密码学研究中非常活跃的一个课题。自主性是信息安全的一个重要特点，在我国，依靠自己的力量并汲取现有的先进经验进行分组密码的研究、设计和开发也是非常必要的。 分组密码的研究内容主要包括三个方面：分组密码的设计原理、分组密码的安全性分析和分组密码的应用研究。围绕着分组密码的安全性分析和设计，本论文取得了以下五个方面的主要研究成果： 1．分别利用差分-非线性密码分析、截断差分-线性密码分析、积分密码分析三种不同的密码分析方法，对Safer++进行了密码分析； 2．在对分组密码的可证明安全性和实际安全性研究的基础上，提出了一个嵌套Feistd结构的SP型分组密码的模型。采用该模型，只需适当选取密码特性好的非线性模块和线性模块，就可以构造出具有很好地抵抗差分密码分析和线性密码分析的能力、加解密相似的分组密码算法； 3．采用上述密码模型，给出了一个用该模型构造的具体的分组密码算法SCF。并且对SCF作了一些初步的密码分析和详细的统计测试，结果表明：SCF密码足够抵抗一些已知的密码分析、具有很好的统计性能。 4．对一类基于混沌函数的分组密码结构GFS4(GFS8)的安全性做了评估，分析结果表明：从抵抗差分密码分析和线性密码分析的安全性与所需要的执行代价相比，这类密码结构不如CAST-256型密码结构和普通的Feistel型密码结构。因此在分组密码的设计中，我们不推荐使用这类密码结构。 5．利用两种方法对一个基于细胞自动机的分组密码系统CAC的变形进行了分析，结果表明：CAC的这种变形在选择明文攻击下是极不安全的。对CAC的变形进行分析的意义在于：知道CAC的具体设计细节后，借鉴对该变形的分析，有可能对CAC密码系统本身的安全性造成威胁。
Modem cryptological theory and cryptological technology are important basis of information security. Block cipher is an important branch of cryptology, it has many attractive features such as high rates, easy for standardization, and efficient for both software and hardware implementations. Block ciphers are usually core components in information and Internet security for data encryption, data signature, authentication and key management.Along with the launch of AES process, block ciphers has become a very active subject in recent years. Autonomy is a notable feature of information security. So it"s very necessary to conduct block cipher research, design and development relying on our own ability, and absorbing advanced experience at the same time.The research contents of block ciphers can be divided into three parts: design principles of block ciphers, security analysis of block ciphers and application research of block ciphers. Concentrating on security analysis and design of block ciphers, five principal achievements have been obtained in this dissertation:1.Using differential-nonlinear cryptanalysis, truncated differential-linear cryptanalysis and integral cryptanalysis respectively, three attacks of reduced-round Safer++ are given;2.Based on the survey of provable security and practical security of block ciphers, a block cipher model of SPN cipher containing Feistel structure is proposed. Adopting this model and properly selecting some nonlinear and linear modules which has good cryptographic properties, a concrete block cipher can thus be constructed, which is provably secure against differential and linear cryptanalysis, and also has self-inverse structure for encryption and decryption.3.Adopting the above model, a concrete block cipher named SCF is proposed. Some initial cryptanalysis and detailed statistical tests of SCF are given, the results show that SCF can resist some known cryptanalytic attacks and has excellent statistical properties.4.Security of a class of block ciphers based on chaotic maps against differential and linear cryptanalysis is studied. The results show that this kind of cipher structure is not good compared with some famous cipher structure such asCAST-256 cipher structure and common Feistel structure. So we don"t recommend this kind of cipher structure when designing a new cipher. 5. Security analyses of a variant of a new block cipher system (called CAC) based on cellular automata theory are given using two cryptanalytic approaches. The results show that this variant of CAC is very insecure under chosen-plaintext attacks. The importance of analysis of this variant is: using cryptanalysis of the variant for reference, attacks on the original cipher may be found when knowing some of the design details of CAC.
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