Published online by Cambridge University Press: 26 August 2011
In the last decade, formal methods have proved their interest whenanalyzing security protocols. Security protocols require inparticular to reason about the attacker knowledge. Two standardnotions are often considered in formal approaches: deducibility andindistinguishability relations. The first notion states whether anattacker can learn the value of a secret, while the latter stateswhether an attacker can notice some difference between protocol runswith different values of the secret. Several decision procedureshave been developed so far for both notions but none of them can beapplied in the context of e-voting protocols, which requirededicated cryptographic primitives. In this work, we show that bothdeduction and indistinguishability are decidable in polynomial timefor two theories modeling the primitives of e-voting protocols.