Secure private fragile watermarking scheme with improved tampering localisation accuracy

In some applications, such as surveillance cameras, it is essential that images acquired with the same device be deemed distinct. To fulfil this requirement, many fragile watermarking methods need to employ a different key for every single image. Keeping track of the correct key associated with each image may become a challenging task as the number of images increases. An existing image index-based scheme as a suitable solution for this problem is revisited, and its security limitations in applications are highlighted where higher localisation accuracy is required. Then, a new fragile watermarking scheme that enhances the localisation accuracy is proposed, while hindering brute force attacks. Experiments demonstrate that the proposed scheme outperforms the state-of-the-art private fragile watermarking methods.