Modified quaternion encryption for DICOM image

This paper studies and implements the existing encryption algorithm on 16-bit DICOM images using quaternions as the key, around which, the pixels of an image are rotated to get another image suitable for transmission over a network, such as internet, to the intended receiver. The existing algorithm is a strong encryption method that gives commendable results for random number sequence generation performed by various random sequence test suite. It also follows the avalanche effect by yielding 50% different result with achange of one bit in the key and effectively withstands a bruteforce and other types of decryption attacks. In this paper, authors have implemented the existing algorithm and subsequently modified it by splitting the image matrix into four smaller matrices instead of two as in the existing algorithm and performing parallel execution of those matrices in group of two to improve the execution time of the algorithm. Thus, it executes faster without affecting or compromising with the image qualityimplying that the strength of the encryption algorithm is not affected as the modification is made only to the way algorithm executes without interfering with the internal structure of the algorithm.