Paper 2019/752
Fact and Fiction: Challenging the Honest Majority Assumption of Permissionless Blockchains
Runchao Han and Zhimei Sui and Jiangshan Yu and Joseph Liu and Shiping Chen
Abstract
Honest majority is the key security assumption of Proof-of-Work (PoW) based blockchains. However, the recent 51% attacks render this assumption unrealistic in practice. In this paper, we challenge this assumption against rational miners in the PoW-based blockchains in reality. In particular, we show that the current incentive mechanism may encourage rational miners to launch 51% attacks in two cases. In the first case, we consider a miner of a stronger blockchain launches 51% attacks on a weaker blockchain, where the two blockchains share the same mining algorithm. In the second case, we consider a miner rents mining power from cloud mining services to launch 51% attacks. As 51% attacks lead to double-spending, the miner can profit from these two attacks. If such double-spending is more profitable than mining, miners are more intended to launch 51% attacks rather than mine honestly. We formally model such behaviours as a series of actions through a Markov Decision Process. Our results show that, for most mainstream PoW-based blockchains, 51% attacks are feasible and profitable, so profit-driven miners are incentivised to launch 51% attacks to gain extra profit. In addition, we leverage our model to investigate the recent 51% attack on Ethereum Classic (on 07/01/2019), which is suspected to be an incident of 51% attacks. We provide insights on the attacker strategy and expected revenue, and show that the attacker’s strategy is near-optimal.
Note: All types of feedback are welcome.
Metadata
- Available format(s)
- Category
- Cryptographic protocols
- Publication info
- Published elsewhere. Minor revision. AsiaCCS'21
- DOI
- 10.1145/3433210.3453087
- Keywords
- BlockchainProof-of-Work51% Attacks
- Contact author(s)
- runchao han @ monash edu,zhimei sui1 @ monash edu,jiangshan yu @ monash edu,joseph liu @ monash edu,shiping chen @ data61 csiro au
- History
- 2021-02-28: last of 11 revisions
- 2019-06-26: received
- See all versions
- Short URL
- https://ia.cr/2019/752
- License
-
CC BY