Joint fingerprinting and decryption method for color images based on quaternion rotation with cipher quaternion chaining

Abstract

This paper addresses the problem of unauthorized redistribution of multimedia content by malicious users (pirates). In this method three color channels of the image are considered a 3D space and each component of the image is represented as a point in this 3D space. The distribution side uses a symmetric cipher to encrypt perceptually essential components of the image with the encryption key and then sends the encrypted data via multicast transmission to all users. The encryption involves rotation, and translation of points in 3D color space using quaternion algebra. Each user has a unique decryption key which is different from the encryption key. The differences between the common encryption key and the individual user’s decryption key cause the decrypted image to contain minor changes which are user’s fingerprint. A computer-based simulation was conducted to examine the method’s robustness against noise, compression, and collusion attacks.