Round Efficient Byzantine Agreement from VDFs

Byzantine agreement (BA) is a fundamental primitive in distributed systems and has received huge interest as an important building block for blockchain systems. Classical byzantine agreement considers a setting where n parties with fixed, known identities want to agree on an output in the presence of an adversary. Motivated by blockchain systems, the assumption of fixed identities is weakened by using a resource-based model. In such models, parties do not have fixed known identities but instead have to invest some expensive resources to participate in the protocol. Prominent examples for such resources are computation (measured by, e.g., proofs-of-work) or money (measured by proofs-of-stake). Unlike in the classical setting where BA without trusted setup (e.g., a PKI or an unpredictable beacon) is impossible for $$t \ge n/3$$ corruptions, in such resource-based models, BA can be constructed for the optimal threshold of $$t