Digital image security using Matrix and non-linear Pixel Transformation

With the increased use of digital images in numerous fields, especially sensitive ones like medicine and military where confidentiality is extremely important, their encryption has become mandatory. This paper depicts our proposed digital image encryption technique which employs two types of non-linear pixel transformation and the traditional Hill cipher which is a Matrix Transformation (MT). While the Hill cipher achieves good amount of diffusion, the two non-linear pixel transformations namely the All Pixel Transformation (APT) and the Interleaved Pixel Transformation (IPT) makes sure that confusion, avalanche effect, and completeness effect occur. The pixel transformation results in the encryption scheme being collision resistive. Simulation results show high sensitivity to key, plaintext and ciphertext changes. From the cryptanalysis point of view, it is highly resistive to known/chosen plaintext and cipher text attacks. Moreover it is a lossless encryption technique and hence apt for securing medical and military imagery.