Two-Level Fingerprinting Codes

TL;DR

This paper introduces two-level fingerprinting codes that organize users hierarchically, enabling identification of guilty users or groups even with large collusions, and provides conditions and constructions for such codes.

Contribution

The paper defines two-level fingerprinting codes, establishes conditions for their traceability, and offers constructions and rate characterizations for these hierarchical codes.

Findings

Conditions for two-level traceability established

Constructed specific two-level fingerprinting codes

Characterized achievable rates for the codes

Abstract

We introduce the notion of two-level fingerprinting and traceability codes. In this setting, the users are organized in a hierarchical manner by classifying them into various groups; for instance, by dividing the distribution area into several geographic regions, and collecting users from the same region into one group. Two-level fingerprinting and traceability codes have the following property: As in traditional (one-level) codes, when given an illegal copy produced by a coalition of users, the decoder identifies one of the guilty users if the coalition size is less than a certain threshold $t$. Moreover, even when the coalition is of a larger size $s$ $(> t)$, the decoder still provides partial information by tracing one of the groups containing a guilty user. We establish sufficient conditions for a code to possess the two-level traceability property. In addition, we also provide constructions for two-level fingerprinting codes and characterize the corresponding set of achievable rates.