Design And Implementation For A Class Of Chaotic Encryption Schemes

This paper introduces the concept of the Shonnon's perfect security into chaoticcryptography and designs a class of chaotic encryption systems who is perfectsecurity in theory. In these systems, we use a class of new compound chaoticmappings, which is chaotic by Deva ney chaotic theory. Then we discuss the invariantdistribution and the good cipher quality of these mappings. It's proven that symbolicsequences generated using finite partition by these mappings have uniformdistribution and are independent of each other. The paper designs an encryptionarchitecture, which links with symbolic sequences are proven is perfect security intheory. In actual applica tion, to the limited precision computation, perfect security ofthe scheme is inaccessible . To fight the limited precision of computer, the paper addssome bit-ma nipulations in encryption algorithm process, this option can possessstrong anti-translated capability in actual applica tion. The actual encryption schemecan resist cipher text-only attack and known-pla intext attack effectively at least. Inalgorithm analysis , the scheme can resist symbolic dynamic analysis and differentialanalysis at least. Therefore, this class of the chaotic cryptographies have thepractica lly applied value . Besides, the article studies some theories about the limitedprecision of computer, establishes the limited precision model based on the schemeand discusses Lyapunov exponent in limited precision computer. At last, we apply anexample of a class of chaotic encryption systems to ima ge encryption . The statistica ltests and related analysis prove that the actual encryption scheme has high security.