Rebop: Reputation-Based Incentives in Committee-Based Blockchains

Abstract

Blockchains based on proof-of-work suffer from serious draw- backs, such as high computational overhead, long confirmation time, and forks. Committee-based blockchains provide an alternative that tackles these problems. These blockchains use a committee to approve a block at each height. However, rewarding the committee for their work is challenging. The reward mechanism must be fair and robust to attacks. In this paper, we study leader-based reward mechanisms in committee-based blockchains in the presence of rational, colluding, and Byzantine committee members. First, we study the incentives of committee members to deviate and show that an existing reward mechanism is susceptible to attacks from both colluding and Byzantine members. We then propose a reputation-based leader selection mechanism that provides sufficient incentives to coerce rational members to abide by the protocol, and significantly limits the possible gains of collusion. Additionally, our approach reduces the ability of Byzantine members to perform targeted attacks.