Broadcast Encryption and Traitor Tracing
Résumé
Broadcast encryption and revocation schemes can be covered by more general primitives such as attribute-based encryption. However, when applying a general framework to a concrete primitive, this often results in impractical schemes. This chapter talks about recent advancements of this approach. A multi-receiver encryption scheme with the ability to trace traitors is called a traitor tracing (TT). The chapter presents an overview of the different techniques for designing broadcast encryption and TT. Combinatorial broadcast encryption schemes are mainly based on a tree structure or on a fingerprinting code. Tree-based schemes support revocation but have limited capacity dealing with tracing traitors, while code-based ones provide traceability but very few support revocation. Fingerprinting with collusion-secure codes allows one to identify a digital document among several copies of it by embedding a fingerprint.