  Blockchain-based consensus protocols present the opportunity to develop new
protocols, due to their novel requirements of open participation and explicit
incentivization of participants. To address the first requirement, it is
necessary to consider the leader election inherent in consensus protocols,
which can be difficult to scale to a large and untrusted set of participants.
To address the second, it is important to consider ways to provide
incentivization without relying on the resource-intensive proofs-of-work used
in Bitcoin. In this paper, we propose a secure leader election protocol,
Caucus; we next fit this protocol into a broader blockchain-based consensus
protocol, Fantomette, that provides game-theoretic guarantees in addition to
traditional blockchain security properties. Fantomette is the first
proof-of-stake protocol to give formal game-theoretic proofs of security in the
presence of non-rational players.
