MULTIPLE RGB IMAGE ENCRYPTION ALGORITHM WITH MULTILAYERS BY AFFINE HILL CIPHER WITH FRDCT AND ARNOLD TRANSFORM

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 RGB images are encoded as a single RGB image by first converting three RGB images into three indexed images by extracting their color maps. These three indexed image are treated as R, G and B channel of a single RGB 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.

Automated summary

This paper investigates the security of multiple images based on affine hill cipher, fractional discrete cosine transform, and Arnold transform. The proposed scheme assures security in time domain, frequency domain, and coordinate domain, with the original images recoverable through proper arrangements of secret keys. The encryption of the images simplifies storage and transmission, and computer simulations have proven the robustness of the approach on standard examples.