基于混沌的信息加密方法研究

【作者】 陈尔东；

【导师】 胡家升；

【作者基本信息】 大连理工大学 ， 信号与信息处理， 2004， 硕士

【摘要】 混沌现象由美国气象学家洛伦兹(Lorenz)于1963年首先发现，其后迅速发展成为一门新兴科学。混沌科学与其他科学相互渗透，在各个学科领域均得到了广泛的应用，被认为是20世纪物理学的三大成就之一。混沌是指在确定性非线性系统中出现的类似随机的行为，混沌系统的最大特点在于系统的演化对初始条件十分敏感，从长期意义上讲系统的未来行为是不可预测的。混沌系统的特性恰恰符合现代密码学随机数发生器的特征，另外混沌信号的非周期性连续宽带频谱，类似噪声的特性，也使它具有天然的隐蔽性，将混沌应用于信息安全领域有着十分广泛的应用前景。 本文对基于混沌的信息加密方法进行了较为全面的研究，并针对目前的一些加密方案进行了改进。 为了选用合适的非线性系统产生混沌，并判定用于信息加密中的信号为混沌信号，本文对混沌理论及用来判定混沌系统的一些特征量进行了研究，并实现了用来计算各种混沌系统李雅普诺夫指数的工具软件。 一种序列随机特性的好坏是衡量它是否适用于加密的一个重要标准。为了测定不同混沌序列的随机特性，以便选用合适的混沌序列，本文根据美国国家标准技术研究所(NIST)制定的一套随机特性测试标准，编程实现了一套随机特性测试软件，对几种二值混沌序列进行统计分析。 混沌信号产生便捷并且具有很好的随机特性，将混沌序列用于图象信息加密有很好的加密效果，但现有的一些基于混沌的图象加密方式难以抵抗已知明文攻击。本文提出了一种新的基于混沌的图象加密方式，能够抵抗已知明文攻击，使得加密安全性得到很大提高。 基于混沌同步的保密通信方案是一种全新的保密通信方式。1990年，Pecora-Carroll首先提出了基于混沌同步的保密通信方案，方案利用了混沌信号所具有的优良特性，具有很高的安全性，之后又有很多文献对该方案进行了改进。本文对基于混沌同步的保密通信方案进行了仿真，并对该类方案的仿真结果进行了评估。更多还原

【Abstract】 Chaos was first discovered by an America meteorologist Lorenz in 1963, and turned into a new science rapidly. Chaos science merged into the other sciences, and was used abroadly in various fields. It was considered to be one of the three greatest physics achievements in twenty century. Chaos is the pseudorandom behavior that appears in confirmed no-linear system, and the greatest characteristic of a chaotic system is that the evolvement of system is very sensitive to initial value, and the future behavior of system is unforeknown in long term. The characteristic of chaotic system is just the same as that of modern cryptology. The continuous broad spectrum and the characteristic like noise make it has the nature of concealment, so chaos has abroad apllication foreground in field of information security.We carry through a complete study of the application of chaos in field of information security in this paper, and improve on some encryption scheme.To select an appropriate no-linear system for generating chaotic signals and judge whether the signals used in encryption is chaotic signals, chaotic theory and parameters for judging chaos is researched in this paper, and the software for calculating Lyapunov Exponents of various chaotic systems is also realized.The randomness of a sequence is an important standard for deciding whether it’s applicable in encryption. To mensurate the randomness of different chaotic sequences, and choose a proper chaotic sequence, a set of randomness tests described by NIST(National Institute of Standards and Technology) are used for the statistical analysis of binary chaotic sequence.Because chaotic signals are easy to generate and have good random property, the application of chaotic sequence in image encryption has good effect, but those image encryption scheme existed can’t resist plain-text attack. The new image encryption scheme based on chaos propsed in this paper can resist plain-text attack, and improve on the security of encryption greatly.Secure communication scheme based on chaotic synchronization is an entirely new secure communication scheme. Pecora and Carroll propose secure communication scheme based on chaotic synchronization first in 1990. The scheme makes use of the good characteristic of chaotic signals, and has high security. Lots of papers improve on the scheme after it has been proposed. We simulate the secure communication scheme based on chaotic synchronization in this paper, and evaluate the simulation results of these schemes.更多还原