ppLeader: Achieving the Privacy-Preserving Leaders in PoS Protocols

Abstract

The proof-of-stake (PoS) mechanism is considered to be a highly desirable alternative to the proof-of-work (PoW) in order to reduce resource consumption. Nevertheless, we identify that the energy efficient PoS-based blockchain consensus protocols bring new privacy concern that the disclosure of block issuer’s privacy (i.e., its account address and the corresponding balance) for the public verification of block.

We present a leader election protocol (named ppLeader) that aims to randomize the relation between stakeholder’s account and the corresponding success probability, such that guarantees the unpredictable leader election, and anonymous block issuing and public verification. In particular, the frequency that a stakeholder being elected cannot be used by the adversary to reveal its target stakeholder’s stakes. To showcase the usability of ppLeader, we apply it to the elegant PoS-based blockchain consensus protocol Ouroboros Praos directly to achieve the enhanced privacy property. Besides the detailed security analysis, we develop a proof-of-concept implementation of ppLeader and conduct extensive experiments to show the practicality.