Access control using authentication and authorization works well for limiting how people use digital resources in a controlled environment, such as the corporate network. But traditional access control schemes do not work as well when the people or resources are outside of the organization’s direct control.
Documents released under non-disclosure agreements illustrate this problem. Once the document has been released to someone outside your organization, that person could make unlimited copies, send the document to your competitor, and so on. Encrypting or password protecting the document does little to deter this unwanted behavior, because the person receiving the document must unlock it to use it. The authorization schemes we’ve discussed don’t address the problem either, because access control depends on a trusted environment. Absent another solution, we’re left with trust and legal remedies.
Digital rights management (DRM) is an attempt to address these problems. Rather than merely controlling the actions that an entity can perform on digital resources, DRM provides mechanisms for controlling the particular uses to which a digital resource can be put. This is a tough problem, and as we’ll see, good solutions are sufficiently draconian that they impose a significant burden on users and have raised the ire of digital rights activists.
Digital leakage is the loss, whether intentional or inadvertent, of confidential data in digital ...