Cryptanalysis of iterative encryption and image sharing scheme based on the VQ attack

Reversible data hiding in encrypted images (RDHEI) is widely employed to protect privacy in images stored on cloud storage. Recently, Yu et al. [22] proposed an effective image encryption scheme called iterative encryption and image sharing (IEIS), which is highly compatible with RDHEI. In this study, we analyze the characteristics of IEIS and present a cryptanalysis scheme based on vector quantization (VQ) attack. To capture the pixel-changing pattern of an image block, the concept of pixel difference matrix (PDM) is introduced. VQ attack is subsequently utilized to estimate the ciphertext block. Furthermore, we employ a well-trained convolutional neural network (CNN) based discriminator to identify the proper block permutation sequence within the secret key space. Experimental results demonstrate the efficacy of our proposed cryptanalysis scheme. Based on our study, we conclude that the IEIS scheme raises security concerns.