Dice Question Streamline Icon: https://streamlinehq.com

Analyze bribery-driven liveness attacks in Proof-of-Stake ledgers

Analyze bribery attacks that target liveness in committee-based Proof-of-Stake blockchains with block-proportional rewards under the paper’s game-theoretic bribery model, determining how abstention or failure to produce/sign blocks (which causes lost rewards) alters parties’ expected utilities and the resulting strategic equilibria.

Information Square Streamline Icon: https://streamlinehq.com

Background

The paper’s analysis focuses on safety violations (e.g., double signing) under two bribery modes—guided and effective—within a formal game-theoretic framework for Proof-of-Stake ledgers. In this setting, rewards are block-proportional and exchange-rate drops are modeled upon attack success.

The authors explicitly note that bribery could also be used to violate liveness (e.g., censorship via abstention or withholding signatures). Because liveness violations directly reduce a participant’s protocol rewards, analyzing such attacks requires handling utility changes that differ from safety-focused deviations, making the problem more complex.

References

Our work also poses various open questions for future work. First, we assume the adversary only wants to break safety. However, bribes could be used to target liveness. A bribed party could try to censor a transaction by not proposing or signing blocks that include it. In this case, abstaining from participation or failing to create a block, which is a liveness violation, results in lost rewards, so the expected block rewards, hence the utility, of a party is affected by the nature of the infraction. Analyzing such liveness attacks is particularly complex and an interesting topic of further exploration.

Blockchain Bribing Attacks and the Efficacy of Counterincentives (2402.06352 - Karakostas et al., 9 Feb 2024) in Section 8 (Conclusion)