Image Encryption Using Modified Elliptic Curve Cryptography and Hill Cipher

Abstract

Currently, the digital communication generates millions of digital data using the digital images. These confidential images must be protected from the intruders over transmission in network channels. To protect the data, in this paper, a combination of Modified Elliptic Curve Cryptography (MECC) and Hill Cipher (HC) (MECCHC) method is proposed. Elliptic curve cryptography (ECC) is an asymmetric key encryption and enhanced further using symmetric encryption of Hill Cipher, allowing simple and fast computations over complex encryption methods of ECC. Adding a layer of Hill Cipher over ECC makes it even more difficult for the intruder attack. Hill Cipher encryption involves multiplication of 4 × 4 key matrix with 4 × 4 chunks of image pixels, where the self-invertible key matrix is derived from the elliptic curve parameters which make decryption process easier and faster without computing the matrix inverse. The MECCHC method is used to encrypt grayscale and color images. The process efficiency of the MECCHC method is evaluated using entropy, peak signal to noise ratio, number of pixels change rate, and unified average changing intensity measures.