Rank Functions Based Inference System for Group Key Management Protocols Verification

Design and veri¯cation of cryptographic protocols has been under investigation for quite sometime. However, most of the attention has been paid for two parties protocols. In group key management and distribution protocols, keys are computed dynamically through cooperation of all protocol participants. Therefore regular approaches for two parties protocols veri¯cation cannot be applied on group key protocols. In this paper, we present a framework for formally verifying of group key management and distribution protocols based on the concept of rank functions. We de¯ne a class of rank functions that satisfy speci¯c requirements and prove the soundness of these rank functions. Based on the set of sound rank functions, we provide a sound and complete inference system to detect attacks in group key management protocols. The inference system provides an elegant and natural proof strategy for such protocols compared to existing approaches. The above formalizations and rank theorems were implemented using the PVS theorem prover. We illustrate our approach by applying the inference system on a generic Di±e-Hellman group protocol and prove it in PVS

How to Tolerate Half Less One Byzantine Nodes in Practical Distributed System

The application of dependability concepts and approaches to the design of secure distributed systems is raising a considerable amount of interest in both communities under the designation of intrusion tolerance. However, practical intrusion-tolerant replicated systems based on the state machine approach can handle at most f Byzantine components out of a total of n=3f+1, which is the maximum resilience in asynchronous systems. This paper extends the normal asynchronous system with a special distributed oracle called TTCB. Using this extended system we manage to implement an intrusion-tolerant service, based on the state machine approach (SMA), with 2f+1 replicas only. Albeit a few other papers in the literature present intrusion-tolerant services based on the SMA, this is the first time the number of replicas is reduced from 3f+1 to 2f+1. Another interesting characteristic of the described service is a low time complexit

Formal Specification and Verification of the Intrusion--Tolerant Enclaves Protocol

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Formal Specification and Verification of the Intrusion-Tolerant Enclaves Protocol

In this paper, we present a correctness proof of the Intrusion-tolerant Enclaves protocol [10]. Enclaves is a group-membership protocol. It assumes a Byzantine failure model, and has a maximum resiliency of one third. To carry out the proof, we adaptively combine a number of techniques, namely model checking, theorem proving and analytical mathematics. We use the..

On the Correctness of an Intrusion-Tolerant Group Communication Protocol

Abstract. Intrusion-tolerance is the technique of using fault-tolerance to achieve security properties. Assuming that faults, both benign and Byzantine, are unavoidable, the main goal of Intrusion-tolerance is to preserve an acceptable, though possibly degraded, service of the overall system despite intrusions at some of its sub-parts. In this paper, we present a correctness proof of the Intrusion-tolerant Enclaves protocol [1] via an adaptive combination of techniques, namely model checking, theorem proving and analytical mathematics. We use Murphi to verify authentication, then PVS to formally specify and prove proper Byzantine Agreement, Agreement Termination and Integrity, and finally we mathematically prove robustness of the group key management module.

Modeling and Verification of Leaders Agreement in the Intrusion-Tolerant Enclaves Using PVS

Enclaves is a group-oriented intrusion-tolerant protocol. Intrusion-tolerant protocols are cryptographic protocols that implement fault-tolerance techniques to achieve security despite possible intrusions at some parts of the system. Among the most tedious faults to handle in security are the so-called Byzantine faults, where insiders maliciously exhibit an arbitrary (possibly dishonest) behavior during executions of the protocol. This class of faults poses formidable challenges to current verification techniques and has been formally verified only in simplified forms and under restricted fault assumptions. In this paper we present our work on the formal verification of the Byzantine fault-tolerant Enclaves [1] protocol. We use PVS to formally specify and prove Proper Byzantine Agreement, Agreement Termination and Integrity

Modeling and Verification of Leaders Agreement in the Intrusion-Tolerant Enclaves Using PVS

Enclaves is a group-oriented intrusion-tolerant protocol. Intrusion-tolerant protocols are cryptographic protocols that implement fault-tolerance techniques to achieve security despite possible intrusions at some parts of the system. Among the most tedious faults to handle in security are the so-called Byzantine faults, where insiders maliciously exhibit an arbitrary (possibly dishonest) behavior during executions of the protocol. This class of faults poses formidable challenges to current verification techniques and has been formally verified only in simplified forms and under restricted fault assumptions. In this paper we present our work on the formal verification of the Byzantine fault-tolerant Enclaves [1] protocol. We use PVS to formally specify and prove Proper Byzantine Agreement, Agreement Termination and Integrity