Selfish Mining in Proof-of-Work Blockchain with Multiple Miners: An Empirical Evaluation
Proof-of-Work blockchain, despite its numerous benefits, is still not an entirely secure technology due to the existence of Selfish Mining (SM) strategies that can disrupt the system and its mining economy. While the effect of SM has been studied mostly in a two-miners scenario, it has not been investigated in a more practical context where there are multiple malicious miners individually performing SM. To fill this gap, we carry out an empirical study that separately accounts for different numbers of SM miners (who always perform SM) and strategic miners (who choose either SM or Nakamoto’s mining protocol depending on which maximises their individual mining reward). Our result shows that SM is generally more effective as the number of SM miners increases, however its effectiveness does not vary in the presence of a large number of strategic miners. Under specific mining power distributions, we also demonstrate that multiple miners can perform SM and simultaneously gain higher mining rewards than they should. Surprisingly, we also show that the more strategic miners there are, the more robust the systems become. Since blockchain miners should naturally be seen as self-interested strategic miners, our findings encourage blockchain system developers and engineers to attract as many miners as possible to prevent SM and similar behaviour.
KeywordsSelfish mining Proof-of-Work blockchain Agent-based model Empirical multiplayer game
The authors gratefully acknowledge financial support from the EPSRC Doctoral Training Partnership, and the use of IRIDIS High Performance Computing Facility at the University of Southampton. We also would like to express our gratitude to all anonymous reviewers for their insightful comments.
- 1.Azaria, A., Ekblaw, A., Vieira, T., Lippman, A.: MedRec: using blockchain for medical data access and permission management. In: 2016 2nd International Conference on Open and Big Data, pp. 25–30 (2016)Google Scholar
- 2.Bitcoin Wiki: Mining (2018). https://en.bitcoin.it/wiki/Mining. Accessed 1 July 2019
- 3.Bitcoin Wiki: Pooled mining (2018). https://en.bitcoin.it/wiki/Pooled_mining. Accessed 14 June 2019
- 4.Bitcoin Wiki: Block (2019). https://en.bitcoin.it/wiki/Block. Accessed 13 June 2019
- 7.Gervais, A., Karame, G.O., Wüst, K., Glykantzis, V., Ritzdorf, H., Capkun, S.: On the security and performance of proof of work blockchains. In: Proceedings of the 2016 ACM SIGSAC Conference on Computer and Communications Security, CCS 2016, pp. 3–16. ACM, New York (2016)Google Scholar
- 9.Kiayias, A., Koutsoupias, E., Kyropoulou, M., Tselekounis, Y.: Blockchain mining games. In: Conitzer, V., Bergemann, D., Chen, Y. (eds.) Proceedings of the 2016 ACM Conference on Economics and Computation, EC 2016, pp. 365–382. ACM Press, New York (2016)Google Scholar
- 10.Liu, H., Ruan, N., Du, R., Jia, W.: On the strategy and behavior of bitcoin mining with n-attackers. In: Proceedings of the 2018 on Asia Conference on Computer and Communications Security, ASIACCS 2018, pp. 357–368. ACM, New York (2018)Google Scholar
- 11.Nakamoto, S.: Bitcoin: a peer-to-peer electronic cash system (2008). https://bitcoin.org/en/bitcoin-paper. Accessed 28 Nov 2015
- 12.Nayak, K., Kumar, S., Miller, A., Shi, E.: Stubborn mining: generalizing selfish mining and combining with an eclipse attack. In: 2016 IEEE European Symposium on Security and Privacy, pp. 305–320. IEEE Press, Los Alamitos (2016)Google Scholar
- 14.Wood, G.: Ethereum: a secure decentralised generalised transaction ledger. Ethereum Project Yellow Paper 151, 1–32 (2014)Google Scholar
- 16.Zyskind, G., Nathan, O., Pentland, A.: Decentralizing privacy: using blockchain to protect personal data. In: 2015 IEEE Security and Privacy Workshops, pp. 180–184 (2015)Google Scholar