Abstract
This paper provides break of an image encryption algorithm suggested by Xu et al. recently in [Commun Nonlinear Sci Numer Simulat 19 (10) 3735-3744 2014]. The authors realized a Laplace transformation based synchronization between two fractional-order chaotic systems to execute error-free encryption and decryption of digital images. The statistical analyses show the consistent encryption strength of Xu et al. algorithm. However, a careful probe of their algorithm uncovers underlying security shortcomings which make it vulnerable to cryptanalysis. In this paper, we analyze its security and proposed chosen plaintext-attack/known plaintext-attack to break the algorithm completely. It is shown that the plain-image can be successfully recovered without knowing secret key. The simulation of proposed cryptanalysis evidences that Xu et al. algorithm is not secure enough for practical utilization.