基于迭代复数模型的多图像无损同步加密算法研究

当前的多图像加密算法都是将多个明文压缩成一幅图像,再进行加密;但压缩易产生块效应。对此,避开压缩,设计图像复数模型,将多个明文以复数形式叠加成复合图像,提出了基于迭代复数模型的多图像无损加密算法。引入DCT(discrete cosine transform)与ZigZag扫描,将多个明文演变为矩阵;设计迭代图像复数模型,将多个矩阵转变成一个复数矩阵,形成实部与虚部;借助Tent混沌映射扰乱复数矩阵的实部与虚部;通过IDCT(inverse discrete cosine transform)机制,形成复合置乱图像;再结合优化序列,构造加密函数,对复合置乱图像进行扩散。通过提取复数矩阵的实部与虚部,即可得到解密图像,彻底消除了失真现象。仿真结果显示:该加密机制高度安全,密文实部与虚部截然不同;且与当前多图像加密机制相比,算法几乎无失真,解密质量更高,显著消除了块效应。

The Study on Synchronous Lossless Encryption Algorithm for Multi-Image Based on Iteration Plural model

The current multi-image encryption algorithms were compressing several images into single image for encryption; but the block effects and crosstalk effects were induced to cause serious distortion of ciphertext by multi-image compressing. So avoiding compression, the image plural model was designed to form the composite image by the superposition of plural mode, and the synchronous lossless encryption algorithm for multi-Image based on iteration plural model. The DCT (Discrete Cosine Transform) and Zigzag scanning to transform multiple images into matrixes; and taking these matrixes into composite matrix for producing the real and imaginary parts by using the iteration image plural model; the position between real and imaginary parts of plural matrix were permutated by Tent map. Then the composite permutation image was formed by the IDCT (Inverse Discrete Cosine Transform). Finally, the double encrypt function was constructed with chaosSphaseSmask to diffusion composite permutation image. The decryption image was obtained by extracting real and imaginary parts of plural matrix to completely eliminate the distortion. Experiment results were showed that this encryption algorithm was highly secure with excellent quality; compared with current multi-image encryption algorithm, the decryption quality of the algorithm in this paper was highest to effectively eliminate the block effects.