Research On Applications Of Chaos-based Encryptions

The fascinating developments in modern cryptography and network communication during the past decade have created a great demand for secure information transmission over the Internet and wireless network. To meet this challenge, a variety of cryptographic techniques have been proposed.Chaotic systems have many good properties, such as the sensitive dependence on initial conditions and control parameters, the density of the set of all periodic points and topological transitivity which are related to some requirements such as confusion and diffusion in cryptography. Therefore, chaos-based encryption techniques play an increasing role in information security.In fact, since 1980s, the idea of using chaotic systems to design new ciphers has attracted more and more attention. The boom of research on chaotic ciphers occurred from 1989, two chaotic ciphers schemes proposed by Matthews, Pecora and Carroll, respectively and much more contributions are made to get many promising achievements. However, recently, a majority of chaotic ciphers were analyzed and proven not to be practicable, efficient and secure. How to design chaos-based encryption scheme in terms of detailed analyses is becoming a key problem that must be solved urgently.Focusing on the design and application of chaotic ciphers, this dissertation contains the following original achievements:Chaos theory is introduced in detail. First, the research history of chaos is reviewed. Second, the definition of chaos is proposed and the criterion and rules of chaos are given. Third, many typical models of chaotic dynamics systems scattering in the whole paper are aggregated. Finally, the relationship between chaos theory and cryptography is compared in detail, and some essential methods to generate random sequences by using chaotic systems are generalized.Detailed analysis of the state-of-the-art techniques in chaos-based cryptography is carried out. Three classical chaos-based encryption schemes were proposed by E. Alvarez, M.S.Baptista and G.Jakmoski respectively from 1998 to 2004. From then on, many modified schemes associated with them have been proposed. Circular cryptanalysis and improvement have been composing the evolution canto of chaos-based symmetric encryption techniques.