On the formal verification of delegation in SESAME

The objective of this paper is to present the verification of delegation in the SESAME protocol, a compatible extension version of Kerberos. For this we use the formal approach presented in Bolignano (1997). This approach is based on the use of state-based general purpose formal methods. It makes a clear separation between modeling of reliable agents and that of intruders. The SESAME protocol allows a principal in the system to delegate his rights to another principal or a group of principals. The formalization is transposed in a quite systematic manner into the Coq prover's formalism, and the complete formal proof is performed. The proof relies on the fact that confidentiality of keys shared by the multiple authorities involved in the protocol is guaranteed.