From Byzantine Replication to Blockchain: Consensus is only the Beginning
This addresses scalability and durability issues in blockchain systems for developers and researchers, though it is incremental as it builds on existing BFT replication libraries.
The paper tackles the limitations of Byzantine Fault-Tolerant (BFT) state machine replication in blockchains beyond consensus, such as durability and decentralized reconfiguration, by proposing SMaRtChain, which improves performance by a factor of eight over a naive implementation and outperforms Tendermint and Hyperledger Fabric in throughput.
The popularization of blockchains leads to a resurgence of interest in Byzantine Fault-Tolerant (BFT) state machine replication protocols. However, much of the work on this topic focuses on the underlying consensus protocols, with emphasis on their lack of scalability, leaving other subtle limitations unaddressed. These limitations are related to the effects of maintaining a durable blockchain instead of a write-ahead log and the requirement for reconfiguring the set of replicas in a decentralized way. We demonstrate these limitations using a digital coin blockchain application and BFT-SMaRt, a popular BFT replication library. We show how they can be addressed both at a conceptual level, in a protocol-agnostic way, and by implementing SMaRtChain, a blockchain platform based on BFT-SMaRt. SMaRtChain improves the performance of our digital coin application by a factor of eight when compared with a naive implementation on top of BFT-SMaRt. Moreover, SMaRtChain achieves a throughput $8\times$ and $33\times$ better than Tendermint and Hyperledger Fabric, respectively, when ensuring strong durability on its blockchain.