A secure and robust hash-based scheme for image authentication

To authenticate an image using a hash function is a challenging task since several core issues like tamper detection, security and robustness needs to be addressed. In this paper, we propose a hash-based image authentication scheme that simultaneously attempts to address these core issues. Unlike most of the existing schemes that use secret key in the feature extraction stage, we use secret key to randomly modulate image pixels to create a transformed feature space. The key-dependent transformed feature space is then used to calculate the image hash. To reduce the size of the hash, a 4-bit quantization scheme is also proposed. The experimental results reported in this paper reveals that the proposed scheme offers good robustness against JPEG compression, low-pass and high-pass filtering. Besides being robust, the proposed hashing scheme can detect minute tampering with localization of the tampered area. These results along with the receiver operating curve (ROC) and security analysis presented in this work makes the proposed technique a candidate for practical digital image signature systems where the transmitted or stored image might undergo JPEG compression, low-pass or high-pass filtering. (C) 2009 Elsevier B.V. All rights reserved.