The Research On Chaos-base Cryptographical Algorithm And Its Key Technologies

Chaotic systems have many properties which can be connect with cryptography and chaos is a new rich source of cryptography. Nowadays, more and more researchers devote their contributions to chaos-based cryptography. But as a new interdisciplinary academic subject, chaotic cryptography is at early stage of development. Though many chaotic ciphers have been proposed, there are still many problems existing in them. This paper involves the research on employed chaotic map, chaotic stream cryptosystems, chaotic block cipher and chaos-based random number generator.At first, a new piecewise liner chaotic map (PLCM) with a segment number parameter (SNP) was advanced. The precision, SNP and the number of iteration were analyzed, and their mathematical relationship was developed. In the digital encryption system using the presented map, the larger the SNP is adopted, the smaller the number of iteration is needed, and hence the higher the encryption speed. With the incorporation of the area-time trade-off parameter, a most appropriate SNP can be achieved, through which the digital system is optimized.The chaotic output-cipher feedback mode (OCFM) stream cipher was developed. And it was resistant to attacks based on chaotic orbits. The chaotic signals were generated based on iterating the piecewise linear chaotic map (PLCM) with a segment number parameter (SNP). The odd bits were used to produce the key streams. After being incorporated, the even bits and ciphers fed back as the next state of the key stream generator. When the chaotic systems were realized with finite precise, the perturbation approach was applied remedying the finite precision effect, and the perturbation signal was m-sequence. The analysis in theory and the experimental results show that the OCFM cipher is secure, and that the encryption speed can be adjusted to meet the applications requirement at the level of algorithm.It was brought forward that a chaotic block cryptosystem is based on the searching through chaotic state space in this paper. Being different from other classical block cipher, the length of blocks of this cryptosystem varies, and there is no direct functional relation. The chaotic system in this cipher behaves as a multi-chaos- systems algorithm because of parametric variation unit, which adds the complication of analysis.The Chaotic Random Number Generator (CRNG) was developed. It was realized by analog circuit, but could be fabricated in standard digital CMOS process. So CRNG could be used for the design of systems on a chip (SOC) as the intelligent property (IP). All capacitors were realized using MOS devices operated in the depletion region, and MOSCAPS were linearized by a series compensation technique. The analysis in theory and the experimental results showed that the random numbers generated by CRNG were excellent.