Image encryption and decryption using Hill cipher and RSA hybrid algorithms

The digital image is a two-dimensional representation made up of pixels with varying intensities. Certain images include sensitive confidential data, highlighting the critical need for image protection. In this research, images are secured using Hill cipher and RSA hybrid Algorithms. The Hill cipher is a symmetric key cryptographic algorithm that utilizes a matrix as its key for both encryption and decryption. It preserves the original file size and accelerates the encryption process. The Rivest-Shamir-Adleman (RSA) algorithm is an asymmetric key cryptographic technique employing a public key for encryption and a private key for decryption. Its security relies on the computational challenge of factoring large numbers into their prime components. Image encryption involves taking the Red-Green-Blue (RGB) values of each pixel in the image, encrypting them using Hill cipher by invertible matrix 3×3 under modulo 256 operation, followed by RSA encryption, resulting in an encrypted image and the RSA key matrix. Decryption involves reversing the encryption steps, which is started by decrypting using RSA algorithm then followed by using Hill cipher. The encryption and decryption are created using Python on the Google Colaboratory platform. The encryption process results in an encrypted image that exhibits a pattern that is highly challenging to discern from the original image. The decryption process effectively reverts the encrypted image back to its original form.