【作者】 王永；

【导师】 廖晓峰； 肖迪；

【作者基本信息】 重庆大学 ， 计算机应用技术， 2007， 博士

【摘要】 随着计算机技术、网络技术的不断发展和应用的日益普及,管理信息系统、电子商务、电子政务、电子邮件、和网络游戏等应用形式纷纷出现在人们的工作和日常生活中,并成为其中不可缺少的部分。信息安全成为了学术界和企业界共同关注的热点。研究信息安全问题具有重大的理论意义和实用价值。加密算法和Hash函数是密码学中的两项基本技术,它们在保证信息安全的过程中发挥着重要的作用。随着数字产品应用的不断深入和攻击手段的不断发展,迫切需要研究和开发出更多安全、高效、可靠的信息安全技术。将混沌理论引入信息安全领域是当前国际非线性科学和信息科学两个学科交叉融合的热门前沿课题之一。本论文主要致力于对基于混沌理论的加密算法和Hash函数构造进行深入的研究,并尝试将其用于保障信息的安全。在本论文中完成了以下的工作:①对混沌的理论和现代密码学作了论述。对基于混沌理论的密码技术的研究现状进行了详细分析。首先对比了混沌理论与密码学的关系,接着按照混沌流密码、混沌分组密码、混沌公钥密码、其它的混沌密码和混沌图像加密方法和混沌Hash函数的顺序,分别对它们进行了详细的介绍。②对一种基于迭代混沌映射的加密算法进行了安全分析,指出了该算法容易受到攻击的原因,并给出了相应的改进措施。然后对设计这类加密算法应注意的问题进行了分析,并提出了一种基于多个Logistic映射的加密算法。③对分段线性混沌映射的差分特性进行了分析,并以此为基础,提出了一种构造S盒的方法。然后利用此构造S盒的方法,设计了一种基于动态S盒的分组加密算法。理论分析和仿真实验结果表明,该算法具有可靠的安全性和加密速度快等优点。④对时空混沌中的一种常用模型——耦合映象格子进行了分析。然后从密码学应用的角度出发,对此模型在计算机有限精度下的混沌序列周期和格子之间的同步稳定性进行了论述。⑤对典型的基于时空混沌的Hash函数构造方案进行了论述。对其中一种Hash函数构造算法存在的不足进行了分析,并提出了相应的改进算法。改进后算法的效率显著提高,且弥补了原算法中存在的碰撞漏洞。⑥将传统的Hash迭代结构与二维耦合映象格子模型结合在一起,提出了一种新的Hash函数构造算法,并从理论和试验两个方面对算法进行了分析。结果表明该算法具有很好的安全性和灵活性。⑦最后对论文工作进行了全面的总结,并对今后的研究方向进行了展望。更多还原

【Abstract】 With the development and popularization of computer and network,information management system, E-commerce, E-government, E-mail and network games are being applied widely and act as a necessary part in the daily lives. Information security has become the common focus of both academia and enterprises. The research on information security has important academic meaning and practical value.Encryption algorithm and Hash function are two basic techniques in cryptography and play an important role in ensuring the security of information. With the widely use of digital products and the evolution of attacks, the research and development of more information security techniques with security, high efficiency and reliability are demanded. Currently, it is one of the hot promising projects on the combination of nonlinear science and information science to apply chaos theory to information security. In this dissertation, chaos-based encryption algorithm and Hash function have been carefully studied and applied to protect the security of information.The following tasks have been accomplished in this dissertation:①Chaos theory and modern cryptography are introduced. Detailed analysis of the state-of-the-art techniques in chaos-based cryptography is carried out. First, the relationship between chaos theory and cryptography is compared. Then, the detailed descriptions of different chaos-based ciphers are given in the order of the chaos-based stream cipher, the chaos-based block ciphers, the chaos-based public key cipher, other chaos-based cipher, the chaos-based image encryption and the chaos-based Hash functions.②The security of a cryptosystem based on iterating a chaotic map is analyzed. A loophole of this cryptosystem is pointed out and a remedial modification is suggested. Furthermore, some issues which should be considered are presented, while designing this kind of cryptosystem. Finally, an encryption algorithm based on multiple Logistic maps is proposed.③The difference of the piecewise linear chaotic map (PCLM) is analyzed. A method to generate S-box is proposed. Based on this method, a block cipher with dynamic S-boxes is presented. Theory analysis and computer simulation results show that this cryptosystem has good security and high speed.④A common used model in spatiotemporal chaotic systems, i.e. the coupled map lattice, is introduced. In order to apply this model in cryptography, two issues are analyzed, which are the periodicity in the finite computer precision and the stability of synchronization between the coupled map lattices.⑤Tow typical schemes of constructing Hash function based on spatiotemporal chaos are analyzed. Some defects of a Hash function scheme are pointed out and the corresponding improvement is proposed. The improved Hash function remedies the loophole of collision in the original one and has higher efficiency.⑥By combining the traditional iteration structure of Hash function with the two dimensional coupled map lattices, a novel Hash function construction is proposed. Theory analysis and computer test results show that it has high security and flexibility.⑦Finally, the research work of this dissertation is summarized, and the future developing direction is indicated.更多还原