Formal Analysis of Multiparty Contract Signing

Multiparty Contract Signing Over a Reliable Network

Most contract signing protocols make use of a trusted third party (TTP) to ensure fairness. It has been shown that in the crash network model, this is inevitable. However, for stronger networks, where misbehavior is allowed but failure excluded, the necessity of a TTP has not yet been debated. We consider a strong network model, that includes reliable broadcast, bounded delays and timestamps an...

Analysis of Probabilistic Contract Signing

We consider the probabilistic contract signing protocol of Ben-Or, Goldreich, Micali, and Rivest as a case study in formal verification of probabilistic security protocols. Using the probabilistic model checker PRISM, we analyse the probabilistic fairness guarantees the protocol is intended to provide. Our study demonstrates the difficulty of combining fairness with timeliness in the context of...

Analysis of Abuse-Free Contract Signing

Game Analysis of Abuse-free Contract Signing

In this paper we report on the verification of two contract signing protocols. Our verification method is based on the idea of modeling those protocols as games, and reasoning about their properties as strategies for players. We use the formal model of alternating transition systems to represent the protocols and alternating-time temporal logic to specify properties. The paper focuses on the ve...

Formal Analysis of FPH Contract Signing Protocol Using Colored Petri Nets

An electronic contract signing protocol is a fair exchange protocol where the parties exchange their signature on a contract. Some contract signing protocols have been presented, and usually they come with an informal analysis. In this paper we use Colored Petri Nets to formally verify the fairness and the resistance to five previously described attacks of FPH contract signing protocol. We have...