Cryptanalysis of an Enhanced Sub-image Encryption Method

The paper presents a cryptanalysis of an enhanced sub-image encryption method recently proposed by Wang et al. in Optics and Lasers in Engineering 86(2016). Their paper shows that a parallel sub-image encryption method proposed by Mirzaei et al. in Nonlinear Dyn. 67(2012) could be attacked by chosen plaintext attack and proposed an enhanced sub-image encryption method claimed to completely resist the chosen plaintext attack. However, the enhanced sub-image encryption method also has some weakness, such as the key streams are independent with the plain-image. In this paper, one chosen plaintext attack type of cryptanalysis is presented for the enhanced sub-image encryption method and completely broken the enhanced sub-image encryption method. The experimental results indicate that the enhanced sub-image encryption method is weak against chosen plaintext attack and should be improved for practical application.