An Algorithm For Compression And Encryption Of Image Based On Chaotic Dynamic Systems

In the paper, we devised an image encryption algorithm during the process of JPEG compression. According to the chaotic theory of dynamic systems and modern cryptography, we solved the following three types of technique. First, how to generate chaotic sequence having good randomness according to the characteristic that logistic chaotic systems are extremely sensitive to the initial condition. Second, how to create a series of one-way hash as block key from the chaotic sequences. Third, during the process of JPEG compression coding, how to realize the image compression and encryption by using the block cipher. In analysis of the algorithm, we studied detailedly the randomicity of the chaotic sequence, the randomicity, security and anti-collision property of the chaotic hash by several methods. The result implied that the algorithm completely satisfied the security requirement at the sense of cryptography. Thus it could be seen that the image encryption algorithm in the process of JPEG compression possessed the good meaning of theory and practical applied future.