Substitution box generation using Chaos: An image encryption application

摘要

There are procedures to encrypt images; however, sometimes there is a loss of information in the decryption process or the key set size is not specifically mentioned. In this research, substitution boxes are built for the Advanced Encryption Standard (AES) cryptosystem using Chaos, and generated by a non-linear differential equation. The boxes’ non-linearity is quantified using the Walsh function. One thousand twenty four boxes are chosen with a non-linearity of 106. To generate a pseudorandom permutation over 256 elements, an algorithm that defines a bijective function is employed. The AES utilized in this article uses 128 bit keys and applies a box in each round; that is, using an array of 10 boxes for each plaintext block of 128 bits. An encryption application for color images is presented. The degree of the encrypted images’ randomness is measured to quantify the cipher quality. Image encryption is performed without information loss. The aim in future is to design a device to encrypt video in a robust manner and in real time without loss of information.