A Gray Image Encryption Technique Using the Concept of Water Waves, Chaos and Hash Function

Abstract

In this article, an innovative encryption technique is developed by getting the inspiration from the natural up-down water wave's phenomena that changes a reflection on pond's surface. The plain image is considered as water pond and stones are throwing on the pond to diffuse the pixels. The direction of diffusion follows the pattern of natural water waves in 360 degrees. The distance traveled by the waves depend upon the weight of the stone i.e. heavier is the stone, longer will be the distance. Each layer of pixels in image represents Crest (Up) and Troughs (Down) around the hitting point of stone. The number of Crest and Troughs generated by a stone in radius are measured and are categorized into 1 to 6 or six levels (Layers). The concept of Crest and Trough in encryption are achieved by addition and subtraction of pseudo-random numbers in the pixel's intensity. The pseudo random numbers are generated from Logistic map and transformed into stones of different weights ranges from 0-255. Before substitution, the pixels are shuffled in 1-dimensional vector using the index values of random numbers. The hash value is used for modification of initial seeds of the Logistic map. The initial seeds of the Logistic map are modified by the output of 256-bit hash function. Finally, the simulated results are compiled which ascertains that the projected algorithm achieves the required security standard with large pool of secret keys.

Keywords

• Water waves substitution
• chaos
• image cryptography
• SHA-2