硕士学位论文
（工程硕士）
混沌映射与流密码相结合的加密算法研究
DESIGN OF CHAOTIC STREAM CIPHER BASED ON LOGISTIC MAPPING
吴卫高
哈尔滨工业大学
2011年6月
国内图书分类号：TP309.7 学校代码：10213
国际图书分类号：681.3 密级：公开
电气工程及自动化学区房政策工程硕士学位论文
混沌映射与流密码相结合的加密算法研究
硕士研究生：吴卫高
导 师：丁宇新副教授
副导师：邓成良教授
申请学位：工程硕士
橡皮泥的玩法工程领域：计算机技术
所在单位：东莞理工学院
答辩日期：2011年6月
授予学位单位：哈尔滨工业大学
Classified Index: TP309.7
U.D.C: 681.3
Disrtation for the Master’s Degree of Engineering
DESIGN OF CHAOTIC STREAM CIPHER BASED
ON LOGISTIC MAPPING
Candidate：Wu Weigao
Supervisor：Associate Prof.Ding Yuxin Associate Supervisor：Prof.Deng Chengliang
Academic Degree Applied for：Master of Engineering Speciality：Computer Science and Technology Affiliation：DongguanUniversity of Technology Date of Defence：June, 2011
Degree-Conferring-Institution：Harbin Institute of Technology
哈尔滨工业大学工程硕士学位论文
摘要
密码学是一门古老而年轻的科学。根据明文消息的加密形式的不同，密码体制可分为分组密码和流密码。对流密码而言，其核心问题是流密码生成器的设计，流密码的强度依赖于密钥流生成器所生成密钥流的类随机性和不可预测性。如果流密码生成器生成的密钥流是一个完全随机的非周期序列，那么我们可用它实现一次一密体制，这种体制理论上具有保密性。
混沌是一种看似无规则的运动，是确定性系统中出现的类似随机的过程。但反应混沌的方程是确定的，混沌对初值和参数极端敏感，即使初值有极微小的变化，系统将引起巨大的变化。从物理上看，运动似乎是随机的。这种对初值的极端敏感性，或者说确定性系统内在的随机性是混沌的基本特征。
常规加密算法较为成熟，密钥空间确定，安全性容易评估；混沌映射具有不可预测性，混沌加密理论上具有良好的扩散和混淆性能，把混沌加密和常规加密结合起来使用，可以进一步加强加密性。本文分别用Logistic映射和Henon映射改造流密码RC4算法，构造新的加密算法，用改造算法产生的伪随机序列对BMP图像进行加解密，并对伪随机序列的加密效果进行分析。
本文主要研究工作包括：
研究了流密码RC4算法，并对其产生的序列进行性能分析；
安徒生童话有哪些童话研究了两种混沌映射Logistic映射和Henon映射；对产生的混沌序列进行分析，并研究了其混沌吸引子的特征；
研究了用Logistic映射和Henon映射分别改造流密码RC4算法，构造新的加密算法，并对改造算法产生的序列进行性能分析；研究了改造算法的吸引子的特征，并用matlab仿真实现；
凉拌洋葱的做法
实现了基于混沌映射的RC4算法的文件加密系统，并对加密系统性能进行分析，验证了本文提出的改
造算法的可行性和实用性。
关键词：流密码；混沌映射；伪随机序列；混沌吸引子
哈尔滨工业大学工程硕士学位论文
Abstract
Cryptology is an ancient and young science. The cipher system can be divided into block cipher and stream cipher according to the different encrypted plaintext mode.The core of stream cipher is the design of key generator. The intension of stream cipher completely depends on the quence's randomicity and indeterminism. If the cipher stream generate by the key generator is a complete stochastic and acylic quence, it can be ud to implement the once a cipher system.阿甘正传英文名
三上家居
Mathematically, chaos is randomness of a simple deterministic dynamical system. The equation to describe chaos is deterministic. But the chaos is nsitive to initial value. The tiny variety of initial value can make the indeterminism variety of the system later. The nsibility to initial value is, a basic character of chaos.
Conventional encryption algorithm is more mature since its encrypt space is deterministic and its saf
ety is easy to be evaluated. Chaotic map is unpredictable; therefore, chaotic encryption theory has excellent diffusion and confusion performance. In this paper the chaotic encryption and conventional encryption are combined together to further strengthen the curity of data. This paper respectively us Logistic map and Henon map to transform stream cipher RC4 algorithm, and to construct a new encryption algorithm, BMP images are encrypted and decrypted through pudo-random quences generated through reconstructing algorithm, and the encryption effect with pudo-random quence analysis is analyzed. In the paper, my studies are as follow:
(1)The paper studies on stream cipher RC4 algorithms and analyzes performance of generated quence;
(2)The paper studies on two chaotic Logistic map and Henon map, and analyzes generated chaotic quence, meanwhile study chaotic attractor characteristics;
(3)The paper studies on using Logistic map and Henon map for respectively reconstructing stream cipher RC4 algorithm, constructing new encryption algorithm, analyzing performance of quence generated through transforming algorithm; in addition, we study reconstruction algorithm to improve attractor characteristics, and u matlab for simulation;
社区志愿服务(4)In the last, I implement the image encryption system bad on chaotic map and RC4 algorithm, and analyze the performance of the encryption system. Finally I demonstrate the feasibility of transformation algorithm propod by the paper.
keywords: Stream Cipher, Chaos, Pudorandom, Chaotic Attractor
