July 9, 2007, Wroclaw, Poland
|Catuscia Palamidessi||Information-hiding protocols as opaque channels|
I will make a brief introduction to the problem of information-hiding, and present some (randomized) protocols designed to provide this property. Then I will introduce an information-theoretic framework in which these protocols are interpreted as channels, and I will discuss various quantitative definitions of their degree of opacity, showing the relation with probabilistic definitions of information-hiding in literature. Further, I will show how the channel matrix associated to such a protocol can be used by an adversary to try to infer the secret information from the observables, using Bayesian inference, and I will discuss how the probability of error (Bayesian risk) depends on the matrix. Finally, I will show some examples of protocol specifications using a probabilistic process calculus, and discuss how to compute the matrix associated to the protocol using model checking techniques.