Cryptanalyzing an Image Encryption Algorithm Underpinned by 2-D Lag-Complex Logistic Map

This paper conducts a security analysis of an image encryption algorithm that employs 2D Lag-Complex Logistic Map (LCLM) as a Pseudo-Random Number Generator (PRNG). This algorithm uses the sum of all pixel values in the plainimage as the initial value for the PRNG, thereby influencing the randomization of basic encryption operations. However, it is observed that certain factors lead to the generation of identical pseudo-random sequences for different plain images. Capitalizing on this vulnerability, we propose a chosen-plaintext attack strategy that effectively cracks the six encryption steps through a divide-and-conquer approach. By exploiting weaknesses inherent in the 2D-LCLM, the number of required chosen plain images is significantly reduced to 5 · log 2 ( MN ) + 95, where MN represents the total pixel count of the plain image.