An innovative technique for image encryption using tri-partite graph and chaotic maps

Abstract

In this article, the concept of a complete 3-Partite graph is used to substitute the pixels of a color image to achieve encryption. Chen’s chaotic system is deployed to generate vertices of a tri-partite directed graph and then paths are established between these vertices. These paths will serve to perform the substitution of individual pixels. The seeds for the chaotic maps are manipulated by the hash value of the plain image to hinder chosen plaintext attack. The inter and intra correlation of pixels of a three color image in one-dimensional vector is distorted using the non-linear system of equations. The different chaotic maps having divergent features are employed to add up complexity in encryption technique. The extensive experiments are applied on different kinds of images and results are compiled. The results show that the proposed system has a strong robustness against different attacks and prove to be an excellent candidate to encrypt colored digital images. It has high scores for the Number of Pixel Change Rate (NPCR), Unified Average Cipher Intensity (UACI), entropy values, low values for Mean Absolute Error (MAE), Chi-Square and variance of histograms for encrypted images. The palpable lead of proposed system has resilience against transmission impairments such as Gaussian, Salt & Pepper and clipping.