Sequential and Dynamic Frameproof Codes

There are many schemes in the literature for protecting digital data from piracy by the use of digital fingerprinting, such as frameproof codes and traitor-tracing schemes. The concept of traitor tracing has been applied to a digital broadcast setting in the form of dynamic traitor-tracing schemes and sequential traitor-tracing schemes, which could be used tocombat piracy of pay-TV broadcasts, for example. In this paper we extend the properties of frameproof codes to this dynamic model, defining and constructing both l-sequential frameproof codes and l-dynamic-frameproof codes. We also give bounds on the number of users supported by such schemes

Optimal sequential fingerprinting: Wald vs. Tardos

We study sequential collusion-resistant fingerprinting, where the fingerprinting code is generated in advance but accusations may be made between rounds, and show that in this setting both the dynamic Tardos scheme and schemes building upon Wald's sequential probability ratio test (SPRT) are asymptotically optimal. We further compare these two approaches to sequential fingerprinting, highlighting differences between the two schemes. Based on these differences, we argue that Wald's scheme should in general be preferred over the dynamic Tardos scheme, even though both schemes have their merits. As a side result, we derive an optimal sequential group testing method for the classical model, which can easily be generalized to different group testing models.Comment: 12 pages, 10 figure

Dynamic Frameproof Codes

There are many schemes in the literature for protecting digital data from piracy by the use of digital fingerprinting, such as frameproof codes, which prevent traitorous users from colluding to frame an innocent user, and traitor-tracing schemes, which enable the identification of users involved in piracy. The concept of traitor tracing has been applied to a digital broadcast setting in the form of dynamic traitor-tracing schemes and sequential traitor-tracing schemes, which could be used to combat piracy of pay-TV broadcasts, for example. In this thesis we explore the possibility of extending the properties of frameproof codes to this dynamic model. We investigate the construction of l-sequential c-frameproof codes, which prevent framing without requiring information obtained from a pirate broadcast. We show that they are closely related to the ordinary frameproof codes, which enables us to construct examples of these schemes and to establish bounds on the number of users they support. We then define l-dynamic c-frameproof codes that can prevent framing more efficiently than the sequential codes through the use of the pirate broadcast information. We give constructions for schemes supporting an optimal number of users in the cases where the number c of users colluding in piracy satisfies c greater than or equal to 2 or c=1. Finally we consider sliding-window l-dynamic frameproof codes that provide ongoing protection against framing by making use of the pirate broadcast. We provide constructions of such schemes and establish bounds on the number of users they support. In the case of a binary alphabet we use geometric structures to describe constructions, and provide new bounds. We then go on to provide two families of constructions based on particular parameters, and we show that some of these constructions are optimal for the given parameters

Cost-Effective Private Linear Key Agreement With Adaptive CCA Security from Prime Order Multilinear Maps and Tracing Traitors

Private linear key agreement (PLKA) enables a group of users to agree upon a common session key in a broadcast encryption (BE) scenario, while traitor tracing (TT) system allows a tracer to identify conspiracy of a troop of colluding pirate users. This paper introduces a key encapsulation mechanism in BE that provides the functionalities of both PLKA and TT in a unified cost-effective primitive. Our PLKA based traitor tracing offers a solution to the problem of achieving full collusion resistance property and public traceability simultaneously with significant efficiency and storage compared to a sequential improvement of the PLKA based traitor tracing systems. Our PLKA builds on a prime order multilinear group setting employing indistinguishability obfuscation (iO) and pseudorandom function (PRF). The resulting scheme has a fair communication, storage and computational efficiency compared to that of composite order groups. Our PLKA is adaptively chosen ciphertext attack (CCA)-secure and based on the hardness of the multilinear assumption, namely, the Decisional Hybrid Diffie-Hellman Exponent (DHDHE) assumption in standard model and so far a plausible improvement in the literature. More precisely, our PLKA design significantly reduces the ciphertext size, public parameter size and user secret key size. We frame a traitor tracing algorithm with shorter running time which can be executed publicly

Efficient Probabilistic Group Testing Based on Traitor Tracing

Inspired by recent results from collusion-resistant traitor tracing, we provide a framework for constructing efficient probabilistic group testing schemes. In the traditional group testing model, our scheme asymptotically requires T ~ 2 K ln N 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 non-adaptive settings.Comment: 8 pages, 3 figures, 1 tabl

Towards Traitor Tracing in Black-and-White-Box DNN Watermarking with Tardos-based Codes

The growing popularity of Deep Neural Networks, which often require computationally expensive training and access to a vast amount of data, calls for accurate authorship verification methods to deter unlawful dissemination of the models and identify the source of the leak. In DNN watermarking the owner may have access to the full network (white-box) or only be able to extract information from its output to queries (black-box), but a watermarked model may include both approaches in order to gather sufficient evidence to then gain access to the network. Although there has been limited research in white-box watermarking that considers traitor tracing, this problem is yet to be explored in the black-box scenario. In this paper, we propose a black-and-white-box watermarking method that opens the door to collusion-resistant traitor tracing in black-box, exploiting the properties of Tardos codes, and making it possible to identify the source of the leak before access to the model is granted. While experimental results show that the method can successfully identify traitors, even when further attacks have been performed, we also discuss its limitations and open problems for traitor tracing in black-box.Comment: This work has been submitted to the IEEE International Workshop on Information Forensics and Security (WIFS) 2023 for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl