Generalizing Multi-party Contract Signing
Multi-party contract signing (MPCS) protocols allow a group of signers to exchange signatures on a predefined contract. Previous approaches considered either completely linear protocols or fully parallel broadcasting protocols. We introduce the new class of DAG MPCS protocols which combines parallel and linear execution and allows for parallelism even within a signer role. This generalization is useful in practical applications where the set of signers has a hierarchical structure, such as chaining of service level agreements and subcontracting.
Our novel DAG MPCS protocols are represented by directed acyclic graphs and equipped with a labeled transition system semantics. We define the notion of abort-chaining sequences and prove that a DAG MPCS protocol satisfies fairness if and only if it does not have an abort-chaining sequence. We exhibit several examples of optimistic fair DAG MPCS protocols. The fairness of these protocols follows from our theory and has additionally been verified with our automated tool.
We define two complexity measures for DAG MPCS protocols, related to execution time and total number of messages exchanged. We prove lower bounds for fair DAG MPCS protocols in terms of these measures.
KeywordsDirected Acyclic Graph Service Level Agreement Trusted Third Party Message Complexity Parallel Complexity
- 1.Asokan, N.: Fairness in electronic commerce. PhD thesis, Univ. of Waterloo (1998)Google Scholar
- 2.Baum-Waidner, B., Waidner, M.: Optimistic asynchronous multi-party contract signing. Research Report RZ 3078 (#93124), IBM Zurich Research Laboratory, Zurich, Switzerland (November 1998)Google Scholar
- 4.Chadha, R., Kremer, S., Scedrov, A.: Formal analysis of multi-party contract signing. In: CSFW 2004, p. 266. IEEE, Washington, DC (2004)Google Scholar
- 5.Even, S., Yacobi, Y.: Relations among public key signature systems. Technical Report 175, Computer Science Dept. Technion, Haifa, Isreal (March 1980)Google Scholar
- 8.Karaenke, P., Kirn, S.: Towards model checking & simulation of a multi-tier negotiation protocol for service chains. In: Int. Found. for Autonomous Agents and Multiagent Systems AAMAS 2010, pp. 1559–1560 (2010)Google Scholar
- 10.Kordy, B., Radomirović, S.: Constructing optimistic multi-party contract signing protocols. In: CSF 2012, pp. 215–229. IEEE Computer Society (2012)Google Scholar
- 11.Kraus, S.: Automated negotiation and decision making in multi-agent environments. In: ACM Multi-agent Systems and Applications, pp. 150–172 (2001)Google Scholar
- 13.Lu, K., Yahyapour, R., Yaqub, E., Kotsokalis, C.: Structural optimisation of reduced ordered binary decision diagrams for SLA negotiation in IaaS of cloud computing. In: Liu, C., Ludwig, H., Toumani, F., Yu, Q. (eds.) ICSOC 2012. LNCS, vol. 7636, pp. 268–282. Springer, Heidelberg (2012)Google Scholar
- 14.Mauw, S., Radomirović, S.: Generalizing Multi-party Contract Signing. CoRR, abs/1501.03868 (Extended version.) (2015), http://arxiv.org/abs/1501.03868
- 15.Mauw, S., Radomirović, S., Dashti, M.T.: Minimal message complexity of asynchronous multi-party contract signing. In: CSF 2009, pp. 13–25. IEEE (2009)Google Scholar
- 18.Schunter, M.: Optimistic Fair Exchange. Phd thesis, Universität des Saarlandes (2000)Google Scholar
- 20.Yaqub, E., Wieder, P., Kotsokalis, C., Mazza, V., Pasquale, L., Rueda, J., Gómez, S.G., Chimeno, A.: A generic platform for conducting SLA negotiations. In: Service Level Agreements for Cloud Computing, pp. 187–206. Springer (2011)Google Scholar