Security considerations for image communication

Abstract

With ever expanding world of digital gadgets and internet services, the information sharing over open networks has also increased manifolds. Thus, protection and security of crucial information from unauthentic usage is an issue of concern. In particular, the security of image information in various application domains like medical, military, biometrics or in banking services is a big challenge. The classical encryption techniques meant for data encryption like AES (Advanced encryption standard) or DES (data Encryption standard) are not suitable for image encryption due to redundancy and highly correlated adjacent image pixels that lead to data inefficiency while transmission. Another reason is that the text encryption methods lack in sufficient speed and power in confusion-diffusion of image data. The images consist of bulk data and encryption may require several rounds of confusion diffusion in order to attain a certain level of secrecy. This makes the process time consuming. Secondly, the algorithm developed for encryption should be optimized for complexity. In other words, there should be a compromise in time and complexity. Thus, the main objective of this work is to design and develop an image security algorithm that may not require several rounds of encryption and moreover it should not be too complex for its hardware implementation. Optical transforms have inherent property of high speed and massive parallelism. However optical implementation requires spatial modulators, lenses and charged coupled devices that need to be alienated very precisely for error free recovery. Therefore, mathematical modelling of these transforms has been extensively used in literature for developing various image encryption algorithms. However, there are certain limitations associated with smaller key space, blind decryption and linearity in the transforms that make the algorithm vulnerable to potential attacks. As a solution to the smaller key space, various researchers have combined chaos-based permutation or substitution or