关键词: 混沌系统, 伪随机序列, 有限精度效应

Abstract: Chaotic encryption has the characteristics of algorithm simplicity, efficiency and security. The finite accuracy effect in computer system leads to the degradation of chaotic dynamics and reduces the security of the system. In this regard, a new chaotic pseudo-random sequence generator is proposed by combining Logistic map and Tent map. By combining chaos, the problem of periodicity of sequence after finite length iteration of a single system is overcome. The system can retain the different effective accuracies of floating-point and fixed-point, and select different encryption strengths according to the importance of plaintexts. The spectral entropy is applied to the degradation analysis of fixed-point chaotic dynamics. The fixed-point single chaotic sequence cannot pass the NIST test, while the combined chaotic sequence under the precision of fixed-point 32 can, indicating that the randomness of the sequence can be improved by adding random scrambling to hybrid chaos. The security test results of the system show that the proposed encryption scheme has good security.

Key words: chaotic system, pseudo-random sequence, finite accuracy effect