Watermarking to Enforce Medical Image Access and Usage Control Policy

In this paper, we propose integrating watermarking technology and access control model in order to enhance the protection of medical images in distributed healthcare infrastructures. For that purpose, we consider the well known organization based access control model (OrBAC) to express policy due to the intrinsic dynamic nature of the healthcare environment. OrBAC advantage is that it can specify contextual authorizations and obligations using "context", a native notion of this model, which may be viewed as a set of conditions to be satisfied when activating a given authorization or obligation. We suggest the embedding of some useful information into one image, information that can be used for tracing or controlling the access/usage of this image. In a more general way, we discuss how loss less or reversible watermarking can be instrumented by the OrBAC model. The loss less property preserves the image diagnostic value but imposes some other constraints. We illustrate the potential of such a watermarking OrBAC access and usage rules based on a new reversible watermarking scheme we proposed. Based on its performances regarding different image modalities, we analyze how this one can be used to convey such access control elements.