Short Paper: An Empirical Analysis of Blockchain Forks in Bitcoin
Temporary blockchain forks are part of the regular consensus process in permissionless blockchains such as Bitcoin. As forks can be caused by numerous factors such as latency and miner behavior, their analysis provides insights into these factors, which are otherwise unknown. In this paper we provide an empirical analysis of the announcement and propagation of blocks that led to forks of the Bitcoin blockchain. By analyzing the time differences in the publication of competing blocks, we show that the block propagation delay between miners can be of similar order as the block propagation delay of the average Bitcoin peer. Furthermore, we show that the probability of a block to become part of the main chain increases roughly linearly in the time the block has been published before the competing block. Additionally, we show that the observed frequency of short block intervals between two consecutive blocks mined by the same miner after a fork is conspicuously large. While selfish mining can be a cause for this observation, other causes are also possible. Finally, we show that not only the time difference of the publication of competing blocks but also their propagation speeds vary greatly.
This work was supported by the German Federal Ministry of Education and Research within the projects KASTEL_IoE and KASTEL_ISE in the Competence Center for Applied Security Technology (KASTEL) and by the state of Baden-Württemberg through bwHPC, bwFileStorage, and LSDF. The authors would like to thank Tim Ruffing and the anonymous reviewers for their valuable comments and suggestions.
- 1.Decker, C., Wattenhofer, R.: Information propagation in the bitcoin network. In: Peer-to-Peer 2013 IEEE Thirteenth International Conference on Computing (P2P), pp. 1–10. IEEE (2013)Google Scholar
- 4.Gencer, A.E., Basu, S., Eyal, I., van Renesse, R., Sirer, E.G.: Decentralization in bitcoin and ethereum networks. arXiv preprint arXiv:1801.03998 (2018)
- 5.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 (2016)Google Scholar
- 6.Kwon, Y., Kim, D., Son, Y., Vasserman, E., Kim, Y.: Be selfish and avoid dilemmas: fork after withholding (faw) attacks on bitcoin. In: Proceedings of the 2017 ACM SIGSAC Conference on Computer and Communications Security. ACM (2017)Google Scholar
- 7.Nakamoto, S.: Bitcoin: A peer-to-peer electronic cash system (2008)Google Scholar
- 8.Narayanan, A., Bonneau, J., Felten, E., Miller, A., Goldfeder, S.: Bitcoin and Cryptocurrency Technologies: A Comprehensive Introduction. Princeton University Press, Princeton (2016). http://bitcoinbook.cs.princeton.edu/