MULTIPLE RGB IMAGE ENCRYPTION ALGORITHM WITH MULTILAYERS BY AFFINE HILL CIPHER WITH FRDCT AND ARNOLD TRANSFORM
Vandana Guleria, D. C. Mishra · Fractals · 2021
In this paper, we aim to investigate the security of multiple images based on affine hill cipher (AHC), fractional discrete cosine transform (FrDCT) and Arnold transform (AT). Three original [Formula: see text] images are encoded as a single [Formula: see text] image by first converting three [Formula: see text] images into three indexed images by extracting their color maps. These three indexed image are treated as [Formula: see text], [Formula: see text] and [Formula: see text] channel of a single [Formula: see text] image. Each channel is first encrypted using cryptographic encryption scheme AHC in time domain. The partially encoded image is transformed to frequency domain using FrDCT. In frequency domain, the partially encoded image is scrambled with the help of AT. The proposed scheme assures security in time domain, frequency domain as well as in coordinate domain. The original images can be recovered correctly by using proper arrangements of secret keys. The storage and transmission of the encrypted image is easy due to single encrypted image. The robustness of the proposed approach is proved by conducting computer simulations on standard examples.