Security analysis of a chaos triggered image encryption scheme

A chaos triggered image encryption scheme was recently proposed [Ramalingam et al., Multimed Tools Appl, 2018, 77(10): 11669–11,692]. In this paper, this scheme was analyzed in detail, and then some shortcomings concerning the scheme were pointed out. For example, the combined chaos systems used in the scheme possess weak chaos characteristics, the scheme is insensitive with respect to cipher images, and above all, it is vulnerable to chosen plaintext attacks. After that, a well-designed chosen plaintext attack method was suggested to attack the equivalent secret keys of the scheme, and then the scheme was successfully deciphered in a short time. So, the scheme cannot be applied to actual communication systems.