Tenderbake -Classical BFT Style Consensus for Public Blockchains

Our work has been originally motivated by Tezos, a public blockchain which focuses on software correctness and which enables formal reasoning and verification. To further strengthen the resilience of Tezos, which now depends on a consensus protocol delivering only probabilistic finality, we propose a consensus protocol that brings deterministic finality. Our solution is backward compatible with the current liquid proof-of-stake system underlying Tezos. The main contributions of this paper are the following: (i) a formal specification of the Dynamic Repeated Consensus (DRC) problem, an adaptation of the repeated consensus problem to dynamic committees, (ii) Tenderbake, a solution to the DRC problem in a Byzantine and partially synchronous system model. In contrast to recent proposals, Tenderbake works with bounded message buffers. This feature represents a countermeasure to spamming and prevents runtime memory errors. For these reasons we think that Tenderbake is suitable for blockchains aiming to guarantee deterministic finality in a public setting