【作者】 贺筠；

【导师】 李志斌；

【作者基本信息】 华东师范大学 ， 系统理论， 2010， 博士

【摘要】 计算机技术的发展使得数字信息的存储和拷贝更加方便,而通信技术的日益完善使得数字信息的传播和应用得到了飞速的发展。因此,数字信息在互联网和无线通信网络中的安全问题日益突出。密码学是信息安全研究的理论基础。基于非线性科学的混沌理论应用于密码学是近二十年来出现的一个研究热点。混沌动力系统的一些特殊性质与传统密码学的要求非常相似,使混沌密码学研究得到了广泛关注。近年来,出现了大量的混沌加密算法,同时,又有许多学者对已经提出的混沌加密方案进行了深入细致的分析研究,促使混沌密码学一步一步向前发展。本论文在目前混沌密码学领域已经取得的研究成果的基础上,主要致力于数字混沌加密算法的分析和设计,以及消息认证码的应用研究。本论文的主要工作包括以下几个方面：1.与低维混沌相比,时空混沌有着更复杂的行为和更丰富的特性。本文提出了一个基于时空混沌模型和多混沌系统的彩色图像加密算法。时空混沌模型使图像中的各个像素相互耦合,比低维混沌有更好的扩散性能；同时,模型中嵌套了多个混沌映射,进一步增加了密钥敏感性。仿真实验说明该算法的安全性和效率较高。2.介绍了一个基于外部密钥的图像加密方案,该方案中各个像素的加密过程相互独立,容易遭受选择明文攻击。在此基础上,提出了一个基于单向耦合映射格子的彩色图像加密算法。方案中某一位置的像素值与其余多个位置的像素值按一定规则相互耦合,增强了扩散性能。实验表明该方案具有较好的安全性。3.分析了一个基于多混沌系统的分组加密方案,指出了该方案易受攻击的原因是密钥流在加密过程中未发生变化。实现了对该方案的选择明文攻击、选择密文攻击和已知明文攻击。然后提出了一个改进算法,使密钥流的产生过程与明文和密文紧密相关,弥补了原算法中存在的安全漏洞。4.提出了一个具有前向安全性质的聚集消息认证方案。该方案适用于无线传感器网络等资源受限的自适应网络环境,同时能有效降低密钥泄露带来的安全风险。然后介绍了一个基于混沌映射的HASH函数计算模型的构造方法。更多还原

【Abstract】 With the rapid development of computer technology, it becomes very convenient to store and duplicate digital information. Moreover, great progress made in telecom-munication technology also helps to spread application of digital information in a wider area. However, security issues in transmissions of digital information through internet or wireless network occur frequently. Cryptology theoretic is the foundation of information security. Chaos encryption based on nonlinear science becomes a hot topic in cryptology research in the past two decades since specific properties in chaotic dynamic systems are similar to traditional cipher. A number of chaos-based encryption schemes are proposed recently, which promote the development of chaos cryptology.This thesis focuses on design of digital chaos encryption algorithm and message authentication code scheme based on chaos. Our main contributions are as follows:1. A stream color image cryptography has been proposed based on spatiotemporal chaos system and multiple chaotic maps. One-way coupled map lattices (OCML) are used to generate pseudorandom sequences and then encrypt image pixels one by one. By iterating randomly chosen chaotic maps from a set of chaotic maps, the generated pseudorandom sequences obtain high initial-value sensitivity and good randomness. Simulation results show that the proposed scheme is efficient and useful for the security of communication system.2. An image encryption scheme based on external secret key is analyzed. Some su-perfluous operations and secure problems are pointed out. And then, an improved color image encryption is proposed, which is based on a chaotic logistic map and a one-way coupled map lattices model. The results of several experimental prove the security robustness of the proposed cryptosystem.3. Security of a scheme based on dynamic sequences of multiple chaotic systems is discussed. We found that this scheme cannot resist chosen plaintext attack, cho-sen ciphertext attack and known plaintext attack. Through some modifications, a securer cipher scheme is proposed that can resist the above three attacks with the same computation efficiency.4. A forward-secure aggregate message authentication code scheme is proposed. In view of the limited space and communication facility of wireless sensor networks, message authentication codes are aggreated. Furthermore, forward security can ensure that all previously generated MAC tags can be still considered to be valid even after the sensor is compromised. An algorithm for parallel keyed hash function construction based on chaotic maps is also introduced.更多还原