Properties and evaluation of fingerprinting codes

The concept of data fingerprinting is of paramount importance in the framework of digital content distribution. This project deals with fingerprinting codes, which are used to prevent dishonest users from redistributing copyrighted material. After introducing some basic notions of coding and fingerprinting theory, the project is divided in two parts. In the first part, we present and analyze some of the main existing fingerprinting codes and we also discuss some new constructions. The study is specifically focused on the estimation of the minimum length of the codes, given the design parameters of the system: number of users to allocate, maximum size of the collusions and probability of identification error. Also, we present some theoretical results about the new code construction studied. Finally, we present several simulations, comparing the different codes and estimating what is the minimum-length code in each region. The second part of the project is devoted to the study of the properties of Reed-Solomon codes in the context of fingerprinting. Codes with the traceability (TA) property are of remarkable significance, since they provide an efficient way to identify traitors. Codes with the identifiable parent property (IPP) are also capable of identifying traitors, requiring less restrictive conditions than the TA codes at the expense of not having an efficient decoding algorithm, in the general case. Other codes that have been widely studied but possess a weaker traitor-tracing capability are the secure frameproof codes (SFP). It is a well-known result that TA implies IPP and IPP implies SFP. The converse is in general false. However, it has been conjectured that for Reed-Solomon codes all three properties are equivalent. In this paper we investigate this equivalence, and provide a positive answer for families of Reed-Solomon codes when the number of traitors divide the size of the code fieldAward-winnin

Almost separating and almost secure frameproof codes over q-ary alphabets

The final publication is available at Springer via http://dx.doi.org/10.1007/s10623-015-0060-zIn this paper we discuss some variations of the notion of separating code for alphabets of arbitrary size. We show how the original definition can be relaxed in two different ways, namely almost separating and almost secure frameproof codes, yielding two different concepts. The new definitions enable us to obtain codes of higher rate, at the expense of satisfying the separating property partially. These new definitions become useful when complete separation is only required with high probability, rather than unconditionally. We also show how the codes proposed can be used to improve the rate of existing constructions of families of fingerprinting codes.Peer ReviewedPostprint (author's final draft

Cryptographic error correction

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006.Includes bibliographical references (leaves 67-71).It has been said that "cryptography is about concealing information, and coding theory is about revealing it." Despite these apparently conflicting goals, the two fields have common origins and many interesting relationships. In this thesis, we establish new connections between cryptography and coding theory in two ways: first, by applying cryptographic tools to solve classical problems from the theory of error correction; and second, by studying special kinds of codes that are motivated by cryptographic applications. In the first part of this thesis, we consider a model of error correction in which the source of errors is adversarial, but limited to feasible computation. In this model, we construct appealingly simple, general, and efficient cryptographic coding schemes which can recover from much larger error rates than schemes for classical models of adversarial noise. In the second part, we study collusion-secure fingerprinting codes, which are of fundamental importance in cryptographic applications like data watermarking and traitor tracing. We demonstrate tight lower bounds on the lengths of such codes by devising and analyzing a general collusive attack that works for any code.by Christopher Jason Peikert.Ph.D