Block Cipher Key Space To Expand Research And Security Chaos

At first, the studying status and development tendency of tradition block encryption and chaos encryption is summarized briefly. As the representative of tradition block encryption algorithm, DES has a deadly weakness that is too small key space to prevent exhaust attacks. AES as a new block encryption algorithm has a more large key space, but there are some difficult in carrying out and in the transition from DES to AES to let AES replace DES to become a universally acceptable encryption algorithm. And also it is needed more times to proof whether AES is security on the attacks of cryptanalysis methods of all kinds. In the aspect of chaos encryption, the principal development is in chaos security communication and chaos block encryption viz the designing methods and projects about random number generators based on chaos. At the present time, chaos encryption has become the important application domain of chaoses study.In the second, to arm at the problem that the key space of DES is too small to prevent exhaust attacks, an expanding key space method is proposed, and a chaotic transformed DES algorithm is constructed. The expanding key space method is based on 3 principles of the Shannon's idea "one-time pad", "infinite key space" and a chaotic system can make out of a determinate random number generator. In tests, DES is used as a basic encryption algorithm, Logistic map as a random number generator to generate a key block sequence. Thus, the key space of DES increases from 2~56 to 2~100. The tests also show that the expanding key space method is easily implemented technically.In the third, the five essential properties of a security chaotic system and a new chaotic system "Tangent-Delay Ellipse Reflecting Cavity map System (TD-ERCS) is introduced which is put forward by our group.And based on the TD-ERCS, a method of simple Pseudo-Random Number Generator (PRNG) is constructed;hence, a TD-ERCS sequence is engendered with the PRNG. Simulation experiments show that there are many special properties in TD-ERCS such as the maximum Lyapunov exponent over zero, unchangeable equiprobability distribution and zero correlation in total field, there exists a square chaotic attractor when tangent delays one unit, and become ergodic state when tangent delays more units than one. And it is being proofed to satisfy the security property in TD-ERCS.At last, the basic statistic characteristics of TD-ERCS sequences and PRNG are studied with statistics analysis and statistics tests. The test methods consist of uniform test, independence test and combinatory rule test. In some test items, comparing that with m-sequences, Logistic sequences, Chebyshev sequences and SCQC sequences, the experimental results show that TD-ERCS sequences have better statistic characteristics.