Semi-fragile Image Authentication Using Robust Image Hashing with Localization

The great advance in image processing demands a guarantee for assuring integrity of images. In this paper, a semi-fragile image authentication technique is proposed, which can detect and localize the malicious alteration distinguishing the content-preserving manipulations, such as JPEG compression, from the content alterations. The original image is divided into large blocks (sub-images) that are also divided into 8x8 blocks. Secure image hashing is utilized to generate the sub-image hash (signature) that may slightly change when the content-preserving manipulations are applied. Then, two sub-image hash copies are embedded into relatively-distant sub-images using a doubly linked chain, which prevents the vector quantization (VQ) attack. The hash bits are robustly embedded in chosen discrete cosine transform (DCT) coefficients exploiting a property of DCT coefficients that is invariant before and after JPEG compression. The experimental results show that the proposed technique successfully detects and localizes the content alterations only. Furthermore, It can effectively resist many attacks such as vector quantization attacks.