Digital image watermarking for joint ownership verification without a trusted dealer

In this paper, we propose a novel watermarking algorithm that makes use of a secret sharing scheme to address the problem of joint ownership verification for a digital image without a trusted dealer, which has not be addressed so far. Given that multiple owners create an image jointly, they collaboratively compute their own distinct keys without anyone else involved. For the watermarking detection, only when certain number of owners present their keys, can the ownership of the image be verified. Any owner alone can not verify the image ownership. In addition, experimental results show that the proposed algorithm has the desired properties such as invisibility, reliable detection and robustness against a wide range of imaging processing operations.