Revisiting blockchain consensus with trusted components

Antão, Tiago Miguel Gomes

http://hdl.handle.net/10400.5/99905

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Authors

Antão, Tiago Miguel Gomes

Advisor(s)

Bessani, Alysson Neves

Heydari, Hasan

Abstract(s)

Blockchain technology, renowned for its robustness and decentralized nature, has revolutionized the way we secure and verify digital transactions. However, most blockchain protocols are not straightforward and require moderate to advanced blockchain expertise to understand them completely. Therefore, simplicity is essential for better comprehending the scope of such protocols, as it improves the verification of their correctness and reduces the possibility of bugs during implementation. Streamlet fills this gap by presenting a simple blockchain protocol that is easy to understand and implement. Nevertheless, some of the design choices hinder the protocol’s efficiency and scalability, leaving room for improvement. Streamlet lacks responsiveness, requires six communication steps to finalize a block, and has a message complexity of O(n3) due to the mechanism of implicit echo. For these reasons, we introduce MINSTREAMLET+, a novel protocol to address the limitations of Streamlet. Specifically, MINSTREAMLET+ is responsive and lowers the message complexity to O(n2) by removing the echo messages. Additionally, this variant of Streamlet employs a local trusted service to improve resilience and block finalization latency. Streamlet and MINSTREAMLET+’s prototypes were developed and evaluated in terms of software metrics and throughput. Cyclomatic complexity analysis demonstrates that MINSTREAMLET+ is 14% more complex than Streamlet with scores of 2.80 and 2.45, respectively. Results from the experimental evaluation show that MINSTREAMLET+ exhibits better performance than Streamlet with an average increase of approximately 215% in throughput. This increase can primarily be attributed to the protocol’s responsiveness, which allows the system to progress optimistically at a faster pace.