Randomized Frameproof Codes: Fingerprinting Plus Validation Minus Tracing

We propose randomized frameproof codes for content protection, which arise by studying a variation of the Boneh-Shaw fingerprinting problem. In the modified system, whenever a user tries to access his fingerprinted copy, the fingerprint is submitted to a validation algorithm to verify that it is indeed permissible before the content can be executed. We show an improvement in the achievable rates compared to deterministic frameproof codes and traditional fingerprinting codes. For coalitions of an arbitrary fixed size, we construct randomized frameproof codes which have an $O(n^2)$ complexity validation algorithm and probability of error $\exp(-\Omega(n)),$ where $n$ denotes the length of the fingerprints. Finally, we present a connection between linear frameproof codes and minimal vectors for size-2 coalitions.