Research On Key Technologies Of Cipher Theory

With the development of the computer network technique, especially internet,problem of data confidentiality, integrity and authentication of electronic data hasalready become an important task. Cryptography is the kernel technology ofinformation security. From the foundation of morden cryptography, each ocountry inthe world has been exploring and developing the self-dependent techqiues ofcryptography to ensure benfits of society and contry during the process ofinformatization. Cellular automata(CA) is a discrete dynamic system composed of time,space and status, whose inherent characteristics of simplicity of component unit,locality of interaction, high parallelism of information processing as well ascomplicated dynamic property makes CA much suitable for cryptograph application.It becomes one of the most promising kernel techniques in the self-independentresearch of the cryptograph.According to status quo of cellular automata, this paper presents two high qualitypseudo random generators based on controllable coupled and two-Dimensional CAwith a trapezoidal structure in stream cipher. From the view of symmetric encryption,two symmetric encryption algorithms based on coupled toggle cellular automata andpairing function is proposed.From the view of public-key cryptosystem,a public-keycryptosystem based on cellular automata is proposed.Main contributions of this dissertation are summarized as follows:(1) A novel cellular automata(CA)-coupling and controllable CA(CCCA) isproposed in this paper. According to character of CCCA, a pseudo random generatingmethod based on CCCA is presented. Randomness test results on CCCApseudorandom number generators (PRNGs) show that they are better thanone-dimensional CA PRNGs and can be comparable to two-dimensional ones.Meanwhile it keeps the structure simplicity of one-dimensional CA. This novel CCCAis widely used in symmetrical cryptography.(2) A novel cellular automata(CA)- two-Dimensional controllable CA with atrapezoidal structure is proposed in this paper. According to characteristics oftwo-Dimensional controllable CA, a pseudo random generating method based ontwo-Dimensional controllable CA with a trapezoidal structure is presented. Simulationdemonstrates that pseudo random bit sequence generator based on the two- dimensional controllable CA with a trapezoidal structure is easily implemented, andcan generate high speed bit sequence and excellent statistical properties.(3) According to characters of coupled and toggle cellular automata, a novelcryptography system is constructed based on coupled toggle cellular automata, usingthe interaction with n cellular automatas. Computer simulation indicates thatcryptosystem can greatly enlarge the key space and effectively resist brute attack; Inthe meantime, the import of random numbers makes that attacker can not obtain uniqueplaintext and corresponding ciphertext, which effectively resists known-plain attackand chosn-cipher attack.(4) A public-key cryptosystem based on cellular automata is proposed. Thisalgorithm employs n one-dimensional reversible cellular automata as secret key, andthe two-dimensional Moore-neighbor irreversible cellular automata constructed byabove cellular automata is taken as the public-key. Both of these keys compose thepublic-key cryptosystem. This algorithm can be implemented simply and is suitable ofimplementation with VLSI, which efficiently solves the bottle-neck phenomenonbrought by the complicated encryption algorithm during the high speed and real timeinformation transmission.(5) According to characters of pairing function, a kind of symmetric encryptionalgorithm based on pairing function is proposed. This algorithm encrypts data byone-time one-key and multiple encryption, its key space is big to enough and defendseffectively ciphertext-only attack of network's illicit users. This algorithm is a dataencryption of safety, reliability and practial.