A new fast image compression–encryption scheme based on compressive sensing and parallel blocks

This paper proposes a new fast image compression–encryption scheme based on compressive sensing and parallel blocks. To reduce the encryption time in the proposed algorithm, the plain image is divided into a predetermined number of blocks, where these blocks are encrypted in parallel, and each block is encrypted using the same steps. Firstly, the block is transformed into a sparse matrix using DWT. Then, a permutation of rows is applied to the sparse matrix which works by generating a vector with the same length as the number of rows of the matrix using the improved Linear Feedback Shift Register. Each row is shifted by using one value of the vector to obtain the permuted matrix. Secondly, the compressed matrix is obtained by applying the CS between the permuted matrix and the measurement matrix, where the measurement matrix is constructed using a 5D hyperchaotic system. Thirdly, all the compressed matrices are combined to obtain the compressed image. Finally, the 5D hyperchaotic system generates a mask, which is then XORed with the compressed image to get the final cipher image. Experimental and analysis results show that the proposed algorithm has good performance in terms of security and compression, as well as low time complexity, and the number of chosen blocks does not affect negatively the security of the proposed algorithm.