Digital Signets - Self-Enforcing Protection of Digital Content

Cynthia Dwork, Jeff Lotspiech and Moni Naor


The problem of protecting digital content -- software, video, documents, music, etc., from illegal redistribution by an authorized user, is the focus of considerable industrial and academic effort. In the absence of special-purpose tamper-proof hardware, the problem has no cryptographically secure solution: once a legitimate user has purchased the content, the user, by definition, has access to the material and can therefore capture it and redistribute it. A number of techniques have been suggested or are currently employed to make redistribution either inconvenient or traceable. We introduce digital signets, a technique for protecting digital content from illegal redistribution. Under the digital signet scheme, a pirate has essentially two choices: either reveal some sensitive information (say credit card number) or employ an underground "channel" of similar bandwidth to the legitimate one, thus making the scheme "self-enforcing".

The work motivates the study of the previously unexamined class of incompressible functions, analysis of which adds a cryptographic twist to communication complexity.

Postscript , gzipped Postscript .

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