An improved watermarking technique for multi-user, multi-right environments

Abstract

In digital rights management, there are many instances where there is more than one user involved, with each user having different level of rights. In this paper, we develop a novel approach to the multi-user, multi-right problem, where users are tied to various rights in an arbitrary access structure. Our approach is applicable to all kinds of media and can be used with any watermarking algorithm, provided that keys are used to generate the watermarks. This flexibility also enables it to benefit from future progress in the development of watermarking algorithms, in particular that of multiple watermarking. The proposed technique uses the generalized secret sharing scheme of Benaloh and Leichter, and builds on the earlier work of Guo on the joint ownership problem. By noting that the number of rights is likely much smaller than the number of users in most practical situations, and by generating the watermarks independently, the proposed approach achieves greater fidelity and detection capability than Guo's schemes while remaining secure against colluding users.