A Novel chaos-based Joint Compression and Encryption scheme using Normalized Conditional Bi-gram Probability

A new approach to enhance the compression performance and execution time of chaos-based joint compression and encryption schemes is proposed. Instead of finding a new method to update the Look-up Table (LUT) in each iteration or using a different method to represent the ciphertext, we use multiple LUTs based on the conditional bi-gram probabilities of two consecutive source symbols occurring in the input. This high order probability model can represent the characteristics of whole input file more accurately. As a result, it will further decrease the search time as well as the length of the resultant ciphertext. Simulation results also verify that the proposed approach does lead to better compression performance and execution efficiency.