Lawrence C. Paulson

Abstract: "Informal arguments that cryptographic protocols are secure can be made rigorous using inductive definitions. The approach is based on ordinary predicate calculus and copes with infinite-state systems. Proofs are generated using Isabelle/HOL. The human effort required to analyze a protocol can be as little as a week or two, yielding a proof script that takes a few minutes to run. Protocols are inductively defined as sets of traces. A trace is a list of communication events, perhaps comprising many interleaved protocol runs. Protocol descriptions incorporate attacks and accidental losses. The model spy knows some private keys and can forge messages using components decrypted from previous traffic. Three protocols are analyzed below: Otway-Rees (which uses shared-key encryption), Needham-Schroeder (which uses public-key encryption), and a recursive protocol [9] (which is of variable length). One can prove that event ev always precedes event ev ́or that property P holds provided X remains secret. Properties can be proved from the viewpoint of the various principals: say, if A receives a final message from B then the session key it conveys is good."

The Inductive Approach to Verifying Cryptographic Protocols

Abstract: "The inductive approach to verifying security protocols, previously applied to shared-key encryption, is here applied to the public key version of the Needham-Schroeder protocol. As before, mechanized proofs are performed using Isabelle/HOL. Both the original, flawed version and Lowe's improved version are studied; the properties proved highlight the distinctions between the two versions. The results are compared with previous analyses of the same protocol. The analysis reported below required only 30 hours of the author's time. The proof scripts execute in under three mintues."

Needham-Schroeder with Public Keys

Mechanized Proofs of Security Protocols

As a generic theorem prover, Isabelle supports a variety of logics. Distinctive features include Isabelle's representation of logics within a meta-logic and the use of higher-order unification to combine inference rules. Isabelle can be applied to reasoning in pure mathematics or verification of computer systems. This volume constitutes the Isabelle documentation. It begins by outlining theoretical aspects and then demonstrates the use in practice. Virtually all Isabelle functions are described, with advice on correct usage and numerous examples. Isabelle's built-in logics are also described in detail. There is a comprehensive bebliography and index. The book addresses prospective users of Isabelle as well as researchers in logic and automated reasoning.

A Generic Theorem Prover

Isabelle

Tobias Nipkow

Markus Wenzel

This volume is a self-contained introduction to interactive proof in high- order logic (HOL), using the proof assistant Isabelle 2002. Compared with existing Isabelle documentation, it provides a direct route into higher-order logic, which most people prefer these days. It bypasses ?rst-order logic and minimizes discussion of meta-theory. It is written for potential users rather than for our colleagues in the research world. Another departure from previous documentation is that we describe Markus Wenzel’s proof script notation instead of ML tactic scripts. The l- ter make it easier to introduce new tactics on the ?y, but hardly anybody does that. Wenzel’s dedicated syntax is elegant, replacing for example eight simpli?cation tactics with a single method, namely simp, with associated - tions. The book has three parts. – The ?rst part, Elementary Techniques, shows how to model functional programs in higher-order logic. Early examples involve lists and the natural numbers. Most proofs are two steps long, consisting of induction on a chosen variable followed by the auto tactic. But even this elementary part covers such advanced topics as nested and mutual recursion. – The second part, Logic and Sets, presents a collection of lower-level tactics that you can use to apply rules selectively. It also describes I- belle/HOL’s treatment of sets, functions, and relations and explains how to de?ne sets inductively. One of the examples concerns the theory of model checking, and another is drawn from a classic textbook on formal languages.

A Proof Assistant for Higher-Order Logic

Isabelle/HOL

Matt Kaufmann

This book constitutes the refereed proceedings of the First International Conference on Interactive Theorem proving, ITP 2010, held in Edinburgh, UK, in July 2010. The 33 revised full papers presented were carefully reviewed and selected from 74 submissions. The papers are organized in topics such as counterexample generation, hybrid system verification, translations from one formalism to another, and cooperation between tools. Several verification case studies were presented, with applications to computational geometry, unification, real analysis, etc.

Lawrence C. Paulson

About

Books

Join the club