Deciding cryptographic protocol adequacy with HOL

Abstract

A cryptographic protocol is an algorithm involving exchanges of encrypted information carried out by principals in a distributed environment. It is intended to produce secure communications, even if every message can be read by, or originate with, every principal. This paper gives a definitional HOL formalization of a “belief logic” based on the full Gong, Needham, and Yahalom [2] logic for analyzing whether protocols achieve desired communication conditions. This gives the “belief logic” a sound formal basis. The paper also sketches the algorithm for a possible HOL tactic automatically constructing proofs that protocols achieve desired communication conditions if they do achieve them.

The author wishes to thank Key Software, particularly Doug Weber, for providing the computing facilities used for this work. Geoffrey Hird answered questions on the Gong, Needham, Yahalom logic. Shiu-Kai Chin provided a copy of HOL90.7. This work was partially supported by Air Force Materiel Command's Electronic Systems Center/Software Center (ESC/ENS), Hanscom AFB, through the Portable, Reusable, Integrated Software Modules (PRISM) contract.