Scalable Byzantine Consensus via Hardware-assisted Secret Sharing (1612.04997v5)

Abstract: The surging interest in blockchain technology has revitalized the search for effective Byzantine consensus schemes. In particular, the blockchain community has been looking for ways to effectively integrate traditional Byzantine fault-tolerant (BFT) protocols into a blockchain consensus layer allowing various financial institutions to securely agree on the order of transactions. However, existing BFT protocols can only scale to tens of nodes due to their $O(n^2)$ message complexity. In this paper, we propose FastBFT, a fast and scalable BFT protocol. At the heart of FastBFT is a novel message aggregation technique that combines hardware-based trusted execution environments (TEEs) with lightweight secret sharing primitives. Combining this technique with several other optimizations (i.e., optimistic execution, tree topology and failure detection), FastBFT achieves low latency and high throughput even for large scale networks. Via systematic analysis and experiments, we demonstrate that FastBFT has better scalability and performance than previous BFT protocols.

• The paper introduces FastBFT, a Byzantine fault-tolerant protocol that achieves O(n) message complexity for scalable consensus by using hardware-assisted secret sharing with trusted execution environments.
• FastBFT demonstrates significantly enhanced scalability and efficiency, achieving over 100,000 transactions per second and outperforming other BFT and crash fault-tolerant protocols in experiments.
• The protocol offers a flexible design framework with substantial implications for integrating scalable BFT into blockchain applications, particularly in high-throughput sectors like finance and supply chain.

Scalable Byzantine Consensus with FastBFT

The paper "Scalable Byzantine Consensus via Hardware-assisted Secret Sharing" introduces FastBFT, a novel Byzantine fault-tolerant (BFT) protocol designed to improve scalability and performance in blockchain systems. FastBFT is developed primarily to address the limitations of existing BFT protocols, which struggle to scale efficiently beyond tens of nodes due to their O(n²) message complexity.

Key Contributions of FastBFT

FastBFT brings forth several key innovations that collectively enhance the protocol's scalability and efficiency:

1. Message Aggregation with TEEs and Secret Sharing: At the core of FastBFT is a message aggregation technique that leverages trusted execution environments (TEEs), such as Intel SGX, in conjunction with lightweight secret sharing. This significant innovation reduces the message complexity from O(n²) to O(n), making the protocol markedly more scalable.
2. Optimistic Execution: FastBFT employs an optimistic BFT paradigm, which ensures that only a subset of nodes need to participate actively in the protocol. This reduces the load on the entire network while maintaining high throughput and low latency.
3. Efficient Topology and Failure Detection: A tree topology is used to balance the communication and computation loads across nodes, and a straightforward failure detection process ensures the system can efficiently handle non-primary faults.
4. Distinct Design Framework: FastBFT presents a flexible framework allowing various design trade-offs between efficiency and resilience. By selecting alternative design paths, one can tailor different BFT variants addressing specific needs or constraints.

Performance and Comparisons

Through systematic experimentation, FastBFT demonstrates significantly enhanced scalability and efficiency compared to existing BFT protocols. Notably, FastBFT manages to sustain high throughput exceeding 100,000 transactions per second with a network size that far exceeds the typical limitations of prior BFT protocols, making it a compelling choice for next-generation blockchain applications.

Compared against Zyzzyva, MinBFT, CheapBFT, and XPaxos, FastBFT showcases superior performance, especially as the number of nodes increases. Its ability to maintain high throughput with increased node count is attributed to the protocol's innovative message aggregation and efficient topology design. Furthermore, FastBFT even outperforms crash fault-tolerant schemes like XPaxos, particularly as tolerance to faults becomes a greater requirement.

Implications and Future Directions

The introduction of FastBFT holds substantial implications for the integration of BFT protocols in blockchain technologies. Its capability to process extensive transactional volumes with high efficiency positions it as a pivotal consensus mechanism in contexts where traditional BFT protocols are rendered inadequate. Practically, this can enhance the financial and operational feasibility of blockchain systems in sectors such as finance and supply chain.

Theoretically, FastBFT opens avenues for further exploration into the amalgamation of cryptographic mechanisms like secret sharing with hardware-enhanced trust frameworks, pushing the boundaries of fault tolerance and scalability in distributed systems. Future work may focus on optimizing the communication topology further or investigating new hardware-based security constructs that could bolster BFT protocols' performance and resilience properties.

In conclusion, FastBFT addresses significant scalability challenges endemic to Byzantine consensus protocols. It stands as a testament to how leveraging trusted hardware and cryptographic techniques can coalesce to overcome complex distributed systems' limitations, ensuring robust and efficient consensus mechanisms for contemporary blockchain applications.