Traitors Collaborating in Public: Pirates 2.0
Olivier Billet and Duong Hieu Phan
Abstract:
This work introduces a new concept of attack against traitor
tracing schemes. We call attacks of this type Pirates 2.0 attacks because
they result from traitors collaborating together in a public way. In other
words, traitors do not secretly collude but display part of their secret
keys in a public place; pirate decoders are then built from the public
information. The distinguishing property of Pirates 2.0 attacks is that
traitors only contribute partial information about their secret key material which suffices to produce pirate decoders while allowing them to
remain anonymous. The side-effect is that traitors can publish their contributed information without the risk of being traced; giving such strong
incentives to some of the legitimate users to become traitors allows coalitions to attain very large sizes that were not realistic in previous classical
models of coalitions.
This paper proposes a generic model for this new threat, that we use to
assess the security of some of the most famous traitor tracing schemes.
We exhibit several Pirates 2.0 attacks against these schemes, providing
new theoretical insights with respect to their security. Moreover, we also
give practical attacks against various instances of these schemes. We
eventually discuss possible variations on the Pirates 2.0 theme.
Ref: In Advances in Cryptology - Proceedings of EUROCRYPT '09, Springer-Verlag, 2009.
To appear