Private Attacks in Longest Chain Proof-of-stake Protocols with Single Secret Leader Elections
This work addresses security vulnerabilities in blockchain protocols, providing concrete metrics for practitioners, though it is incremental as it builds on existing leader election mechanisms.
The paper quantified the security improvement of Single Secret Leader Elections (SSLE) over Probabilistic Leader Elections (PLE) in proof-of-stake longest-chain protocols, showing that SSLE reduces settlement time by about 25% for a 33% or 25% adversary and increases the security threshold by 10% (from 0.26 to 0.36) while decreasing settlement time by roughly 70% for a 20% adversary.
Single Secret Leader Elections have recently been proposed as an improved leader election mechanism for proof-of-stake (PoS) blockchains. However, the security gain they provide has not been quantified. In this work, we present a comparison of PoS longest-chain protocols that are based on Single Secret Leader Elections (SSLE) - that elect exactly one leader per round - versus those based on Probabilistic Leader Elections (PLE) - where one leader is elected on expectation. Our analysis shows that when considering the private attack - the worst attack on longest-chain protocols - the security gained from using SSLE is substantial: the settlement time is decreased by roughly 25% for a 33% or 25% adversary. Furthermore, when considering grinding attacks, we find that the security threshold is increased by 10% (from 0.26 in the PLE case to 0.36 inthe SSLE case) and the settlement time is decreased by roughly 70% for a 20% adversary in the SSLE case.