Study On Chaotic Block Cryptography And Its Applications

With the rapid development and extensive applications of information and communication technology, the foundation and global role of network and information systems have been progressively strengthened. As a result, the security and protection of network information are becoming increasingly a key problem that must be solved urgently.Since 1980s, the idea of using chaotic systems to design new ciphers has attracted more and more attention. The usefulness of chaos in cryptography depends on the natural relationship between the two research areas: strong dynamical properties of chaotic systems imply strong cryptographical properties of cryptosystems, and the basic way to design cryptosystems containing good strong cryptographical properties implies quasi-chaos. The boom of research on chaotic ciphers occurred from 1989, two chaotic ciphers schemes proposed by Matthews, Pecora and Carroll, and much more contributions are made to get many promising achievements. Although a number of recently proposed chaotic ciphers have been cryptanalyzed, however, many others have not been effectively attacked yet. At the same time, some systematic ways to design chaotic ciphers have been proposed with careful considerations on the security of algorithms such as, e.g., the chaotic block ciphers based on S-boxes.This dissertation focuses on the design and application of chaotic ciphers. Generally, it can be divided into three parts: the design of S-boxes based on chaotic systems (fixed or dynamic S-box), the design of various block ciphers based on chaotic systems, and the application in digital watermark of chaotic ciphers. Specifically, the main achievements and originality contained in this dissertation are as follows:1. The research status and advances of chaotic ciphers has been summarized, analyzed and overviewed. The analyzing method of chaotic block cipher has been expatiated in detail, and several existent key problems to be solved urgently have been pointed out.2. The problem how to utilize chaotic systems to construct cryptographically strong S-boxes has been studied. In traditional block cipher, the S-box is the only one nonlinear core component and it determines the strength of these cryptosystems. Therefore, the construction of cryptographically strong S-boxes is of much...