An image compression encryption scheme based on chaos and SPECK-DCT hybrid coding

In recent years, image compression and encryption joint algorithms usually focus on only one kind of lossless compression or lossless compression, and the image compression coding method is relatively simple. This paper designs a hybrid image compression coding based on the frequency domain structure, combining the advantages of SPECK lossless compression and DCT lossy compression to achieve targeted compression. To further ensure the security of hybrid coding, a new four-dimensional hyperchaotic system is constructed in this paper. Based on the pseudo-random sequence generated by the hyperchaotic system and the SPECK-DCT hybrid coding characteristics, different encryption operations are embedded to enable compression and encryption to be carried out simultaneously, and an encryption algorithm for compressed data is designed. Moreover, simulation results and analysis show that the proposed compression encryption scheme balances various compression properties, including compression ratio, reconstruction quality and operation efficiency, and has good security performance with large key space, information entropy, correlation coefficient and other security indexes close to theoretical values.