Fairness Analysis for Multiparty Nonrepudiation Protocols Based on Improved Strand Space

Lei Li,Licheng Wang,Zhihong Zhang,Jing Chen,Ruiming Wang

doi:10.1155/2014/904717

Abstract

Aimed at the problem of the fairness analysis for multiparty nonrepudiation protocols, a new formal analysis method based on improved strand space is presented. Based on the strand space theory, signature operation is added; the set of terms, the subterm relation and the set of penetrator traces are redefined and the assumption of free encryption is extended in the new method. The formal definition of fairness in multi-party non-repudiation protocols is given and the guideline to verify it based on improved strand space is presented. Finally, the fairness of multi-party non-repudiation protocols is verified with an example of Kremer-Markowitch protocol, which indicates that the new method is suitable for analyzing the fairness of multiparty nonrepudiation protocols.

Highlights

As a crucial foundation of the realization of electronic commerce, nonrepudiation protocols provide the nonrepudiation services for the interbehavior between the network entities
The improved strand space method is a formal analysis method consisting of some key concepts, for example, the redefined term set, relations between subterms, penetrator traces, extended assumption of free encryption, and the bundles in the basic strand space, and combining with protocol traces and theorem proof
L, ER󸀠 (k)), we assume that term node n3, and we investigate the probability of positive node in the penetrator traces, respectively: (1) ⟨+w⟩, w ∈ W; it follows from the assumption of free encryption that Zck ⫅¡ w n3 is not its positive node; (2) ⟨+k⟩, k ∈ K; it follows from the assumption of free encryption that Zck ⫅¡ k; n3 is not its positive node; (3) ⟨−g, −h, +gh⟩; if n3 is its positive node, Zck ⫅ gh and we can confirm that Zck ⫅ there obviously exists positive gn∨odZeckn󸀠⫅tho

Summary

Introduction

As a crucial foundation of the realization of electronic commerce, nonrepudiation protocols provide the nonrepudiation services for the interbehavior between the network entities. The formal analysis methods based on nonrepudiation protocols can be divided into two classes. In the strand space theory, some cryptographic primitives are lack of definition, such as signature; it is not suitable for the analysis of the fairness for multi-party nonrepudiation protocols. The formal definition of fairness in multi-party nonrepudiation protocols is given and the guideline to verify it based on improved strand space is presented. (2) If n1, n2 ∈ N, n1 → n2 means that term (n1) = +a and term (n2) = −a It means that node n1 sends the message a, which is received by n2, creating a causal link between their strands. (5) I is an unsigned term set, node n ∈ N is an entry point of I, if and only if (n) = +t, and whenever n󸀠 precedes n on the same strand, t ⫅ term (n).

The Improved Strand Space

Definition of Fairness and Proof Line

Prove the Fairness of KM Protocol Based on Extended strand Method

Conclusions