Security enhancement and analysis of images using a novel Sudoku-based encryption algorithm

This paper presents a novel approach for encrypting images using a Sudoku as its encryption key. This algorithm uses both symmetric and asymmetric key cryptography. It works with any type of data, Sudoku size, and keyspace. The image undergoes the process of modified thresholding, using a pseudo-random number generated from a Sudoku as the threshold. This image is then padded with zeros or the average pixel values to ensure the dimensions are multiples of the Sudoku's size and the image rows are shuffled randomly. For each iteration, the image rows are shuffled, followed by the columns, and finally, the image is rotated clockwise by 90 degrees. The resultant image is highly encrypted and resilient to brute-forcing methods. The algorithm requires roughly 25 milliseconds per iteration for a colored square image of dimensions $512 \times 512$512x512 and has an NPCR value of 99.60% and a UACI value of 35.65%. The gargantuan keyspace offered by the Sudoku keys ensures obedience of Kirchoff's principle and Shannon's maxim.