An inductive approach to strand spaces

In this paper, we develop an inductive approach to strand spaces, by introducing an inductive definition for bundles. This definition provides us not only a constructive illustration for bundles, but also an effective and rigorous technique of rule induction to reason about properties of bundles. With this induction principle, we can prove that our bundle model is sound in the sense that a bundle is a causally well-founded graph. This approach also gives an alternative to rigorously prove a generalized version of authentication tests. To illustrate the applicability of our approach, we have performed case studies on verification of secrecy and authentication properties of the Needham–Schroeder–Lowe and Otway–Rees protocols. Our approach has been mechanized using Isabelle/HOL.