Security analysis of an image encryption algorithm based on paired interpermuting planes and a modified scheme.

This paper analyzes the security issues of the recently proposed image encryption scheme based on paired interpermuting planes. The permutation process of the scheme is designed to permute the pixel values between colour channels and in the diffusion process, the function value of previous cipher is xored to the current pixel, where the function is a permutation map. For a single round encryption/decryption, the chosen plaintext/ciphertext attack is performed to find the permutation map and the keys of the permutation process. A modified scheme is proposed in which the permutation is done in two stages, within the colour channel using generalised cat map and between the colour channels that depends on the values of the pixel after the permutation within the colour channel. The diffusion process chooses the xoring value based on the previous pixel cipher value and the pixel location. These processes are designed to overcome the weaknesses identified and the to resist the chosen plaintext/ciphertext attack. [ABSTRACT FROM AUTHOR]