Cryptology ePrint Archive: Report 2013/420
The Holey Grail: A special score function for non-binary traitor tracing
B. Skoric and J.-J. Oosterwijk and J. Doumen
Abstract: We study collusion-resistant traitor tracing in the simple decoder approach, i.e. assignment of scores for each user separately.
We introduce a new score function for non-binary bias-based traitor tracing. It has three special properties that have long been sought after:
(i) The expected score of an innocent user is zero in each content position.
(ii) The variance of an innocent user's score is~1 in each content position.
(iii) The expectation of the coalition's score does not depend on the
We also find a continuous bias distribution that optimizes the asymptotic (large coalition) performance.
In the case of a binary alphabet our scheme reduces exactly to the
symmetrized Tardos traitor tracing system.
Unfortunately, the asymptotic fingerprinting rate
of our new scheme decreases with growing alphabet size.
We regret to inform you that this grail has holes.
Category / Keywords: traitor tracing
Date: received 27 Jun 2013
Contact author: b skoric at tue nl
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Version: 20130702:185515 (All versions of this report)
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