Bullshark: DAG BFT Protocols Made Practical

01/14/2022

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by   Neil Giridharan, et al.

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We present Bullshark, the first directed acyclic graph (DAG) based Byzantine Fault tolerant (BFT) protocol that is optimized for partial synchrony. Bullshark inherits all the desired properties of its predecessor (DAG-Rider) such as optimal amortized complexity, asynchronous liveness, zero-overhead, and post-quantum safety, but at same time Bullshark provides a practical low latency fast-path that exploits synchronous periods. In addition, we introduce a stand alone partially synchronous version of Bullshark and evaluate it against the state of the art. The resulting protocol is embarrassingly simple (20 LOC on top of a DAG-based mempool implementation) and highly efficient, achieving for example, 125k transaction per second and 3 seconds latency with 50 nodes.