Known-plaintext attack (KPA) on an image encryption scheme using enhanced skew tent map (ESTM) and its improvement

Abstract

Recently, the Skew Tent Map (STM) is enhanced and used for designing the image encryption scheme based on confusion-diffusion. It is claimed that this scheme is secure against various cryptanalytical attacks. In this paper, KPA is applied to this scheme, and the cipher image is decrypted successfully with the help of only one known plain/ cipher image pair in real-time. This attack is implemented in MATLAB and the results are demonstrated. Further, the reasons for the applicability of this attack are found. Finally, the scheme is improved in such a way that it resists KPA as well as maintains the properties of the original scheme.