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A CapacityAchieving Simple Decoder for BiasBased Traitor Tracing Schemes
"... Abstract—We investigate alternative suspicion functions for biasbased traitor tracing schemes, and present a practical construction of a simple decoder that attains capacity in the limit of large coalition size c. We derive optimal suspicion functions in both the RestrictedDigit Model and the Comb ..."
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Abstract—We investigate alternative suspicion functions for biasbased traitor tracing schemes, and present a practical construction of a simple decoder that attains capacity in the limit of large coalition size c. We derive optimal suspicion functions in both the RestrictedDigit Model and the CombinedDigit Model. These functions depend on information that is usually not available to the tracer – the attack strategy or the tallies of the symbols received by the colluders. We discuss how such results can be used in realistic contexts. We study several combinations of coalition attack strategy versus suspicion function optimized against some attack (another attack or the same). In many of these combinations the usual codelength scaling ℓ ∝ c 2 changes to a lower power of c, e.g. c 3/2. We find that the interleaving strategy is an especially powerful attack. The suspicion function tailored against interleaving is the key ingredient of the capacityachieving construction. Index Terms—Collusion resistance, traitor tracing. I.
Dynamic traitor tracing for arbitrary alphabets: divide and conquer
 In IEEE Workshop on Information Forensics and Security (WIFS
, 2012
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Efficient probabilistic group testing based on traitor tracing
 In preparation
, 2013
"... Abstract — Inspired by recent results from collusionresistant traitor tracing, we provide a framework for constructing efficient probabilistic group testing schemes. In the traditional group testing model, our scheme asymptotically requires T ∼ 2K lnN tests to find (with high probability) the corre ..."
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Abstract — Inspired by recent results from collusionresistant traitor tracing, we provide a framework for constructing efficient probabilistic group testing schemes. In the traditional group testing model, our scheme asymptotically requires T ∼ 2K lnN tests to find (with high probability) the correct set of K defectives out of N items. The framework is also applied to several noisy group testing and threshold group testing models, often leading to improvements over previously known results, but we emphasize that this framework can be applied to other variants of the classical model as well, both in adaptive and in nonadaptive settings. I.
Tuple decoders for traitor tracing schemes
, 2014
"... In the field of collusionresistant traitor tracing, Oosterwijk et al. recently determined the optimal suspicion function for simple decoders. Earlier, Moulin also considered another type of decoder: the generic joint decoder that compares all possible coalitions, and showed that usually the generic ..."
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Cited by 2 (2 self)
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In the field of collusionresistant traitor tracing, Oosterwijk et al. recently determined the optimal suspicion function for simple decoders. Earlier, Moulin also considered another type of decoder: the generic joint decoder that compares all possible coalitions, and showed that usually the generic joint decoder outperforms the simple decoder. Both Amiri and Tardos, and Meerwald and Furon described constructions that assign suspicion levels to ctuples, where c is the number of colluders. We investigate a novel idea: the tuple decoder, assigning a suspicion level to tuples of a fixed size. In contrast to earlier work, we use this in a novel accusation algorithm to decide for each distinct user whether or not to accuse him. We expect such a scheme to outperform simple decoders while not being as computationally intensive as the generic joint decoder. In this paper we generalize the optimal suspicion functions to tuples, and describe a family of accusation algorithms in this setting that accuses individual users using this tuplebased information.
Dynamic Traitor Tracing Schemes, Revisited
, 2014
"... We revisit recent results from the area of collusionresistant traitor tracing, and show how they can be combined and improved to obtain more efficient dynamic traitor tracing schemes. In particular, we show how the dynamic Tardos scheme of Laarhoven et al. can be combined with the optimized score ..."
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We revisit recent results from the area of collusionresistant traitor tracing, and show how they can be combined and improved to obtain more efficient dynamic traitor tracing schemes. In particular, we show how the dynamic Tardos scheme of Laarhoven et al. can be combined with the optimized score functions of Oosterwijk et al. to trace coalitions much faster. If the attack strategy is known, in many cases the order of the code length goes down from quadratic to linear in the number of colluders, while if the attack is not known, we show how the interleaving defense may be used to catch all colluders about twice as fast as in the dynamic Tardos scheme. Some of these results also apply to the static traitor tracing setting where the attack strategy is known in advance, and to group testing. 1
Discrete distributions in the Tardos scheme, revisited
 In 1st ACM Workshop on Information Hiding and Multimedia Security (IH&MMSec
, 2013
"... ABSTRACT The Tardos scheme is a wellknown traitor tracing scheme to protect copyrighted content against collusion attacks. The original scheme contained some suboptimal design choices, such as the score function and the distribution function used for generating the biases.Škorić et al. previously ..."
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ABSTRACT The Tardos scheme is a wellknown traitor tracing scheme to protect copyrighted content against collusion attacks. The original scheme contained some suboptimal design choices, such as the score function and the distribution function used for generating the biases.Škorić et al. previously showed that a symbolsymmetric score function leads to shorter codes, while Nuida et al. obtained the optimal distribution functions for arbitrary coalition sizes. Later, Nuida et al. showed that combining these results leads to even shorter codes when the coalition size is small. We extend their analysis to the case of large coalitions and prove that these optimal distributions converge to the arcsine distribution, thus showing that the arcsine distribution is asymptotically optimal in the symmetric Tardos scheme. We also present a new, practical alternative to the discrete distributions of Nuida et al. and give a comparison of the estimated lengths of the fingerprinting codes for each of these distributions.
Binary and qary Tardos codes, revisited
"... The Tardos code is a much studied collusionresistant fingerprinting code, with the special property that it has asymptotically optimal length m ∝ c 2 0, where c0 is the number of colluders. In this paper we simplify the security proofs for this code, making use of the Bernstein inequality and Benne ..."
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The Tardos code is a much studied collusionresistant fingerprinting code, with the special property that it has asymptotically optimal length m ∝ c 2 0, where c0 is the number of colluders. In this paper we simplify the security proofs for this code, making use of the Bernstein inequality and Bennett inequality instead of the typically used Markov inequality. This simplified proof technique also slightly improves the tightness of the bound on the false negative error probability. We present new results on code length optimization, for both small and asymptotically large coalition sizes.
Asymptotic fingerprinting capacity in the Combined Digit Model
, 2012
"... We study the channel capacity of qary fingerprinting in the limit of large attacker coalitions. We extend known results by considering the Combined Digit Model, an attacker model that captures signal processing attacks such as averaging and noise addition. For q = 2 we give results for various atta ..."
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We study the channel capacity of qary fingerprinting in the limit of large attacker coalitions. We extend known results by considering the Combined Digit Model, an attacker model that captures signal processing attacks such as averaging and noise addition. For q = 2 we give results for various attack parameter settings. For q ≥ 3 we present the relevant equations without providing a solution. We show how the channel capacity in the Restricted Digit Model is obtained as a limiting case of the Combined Digit Model.