Embedding a Deterministic BFT Protocol in a Block DAG

TL;DR

This paper formalizes how block DAGs can encode distributed protocols and demonstrates embedding any deterministic BFT protocol into a block DAG while preserving safety and liveness.

Contribution

It introduces a method to embed deterministic BFT protocols into block DAGs, ensuring their core properties are maintained in the new structure.

Findings

Embedding preserves safety and liveness properties.

Block DAGs serve as reliable channels for protocol interactions.

The approach enables efficient message compression.

Abstract

This work formalizes the structure and protocols underlying recent distributed systems leveraging block DAGs, which are essentially encoding Lamport's happened-before relations between blocks, as their core network primitives. We then present an embedding of any deterministic Byzantine fault tolerant protocol $\mathcal{P}$ to employ a block DAG for interpreting interactions between servers. Our main theorem proves that this embedding maintains all safety and liveness properties of $\mathcal{P}$. Technically, our theorem is based on the insight that a block DAG merely acts as an efficient reliable point-to-point channel between instances of P while also using $\mathcal{P}$ for efficient message compression.