基于物理混沌的混合图像加密系统研究

Cascaded image encryption systems based on physical chaos

初步实现了基于物理混沌的混沌和数据加密标准算法级联的混合图像加密系统,基于该系统研究了级联加密与单级加密的抗统计分析能力,以及不可预测性强弱不同的混沌信号在该系统中应用时密文特性的不同.这种利用物理混沌不可预测性的混合加密系统,不存在确定的明文密文映射关系,而且密文统计特性也应优于(或大致相当)其他加密系统.数值结果支持这一结论,同时表明不可预测性较强的混沌系统其加密产生的密文相关性较弱.

A cascaded encryption scheme using physical chaos is realized primarily, which combines chaotic encryption with data encryption standard. The difference of statistical properties of cipher text is studied for two cases. One case is that the ciphertexts come from different schemes, i.e. the cascaded and the single-stage ones, respectively. The other is that the ciphertexts are generated by chaotic signals with different unpredictability in the same scheme. Because physical chaos is adopted in this system, there is no assured relationship between plaintexts and ciphertexts, and the statistical characteristics of ciphertexts should be better than （or about equal to） that of any other encryption system. The experimental results support this conclusion, and show that the stronger unpredictability of chaotic signals causes the weaker correlation of ciphertexts.