Transaction Capacity, Security and Latency in Blockchains

2024-02-15

arXiv.org

AI Summary

This paper addresses the intrinsic coupling among block confirmation depth (k), security, latency, and throughput in Nakamoto consensus. We establish a batch-service queuing model under exponential network delay and, for the first time under this assumption, rigorously derive the security–latency trade-off boundary. Methodologically, we unify consensus security analysis, queuing-theoretic modeling, and an extended selfish mining attack framework to jointly quantify transaction confirmation security, sustainable transaction rate, and average confirmation latency. Our key contributions are: (1) an explicit closed-form threshold for the minimal confirmation depth (k) required to guarantee a target security probability; (2) a tight upper bound on the sustainable transaction rate; and (3) a characterization of how latency distribution shape fundamentally governs the “capacity–security–latency” trilemma, along with a quantitative assessment of selfish mining’s detrimental impact on system throughput.

Technology Category

• Multiagent Systems: Mechanism Design
• Data Mining & Knowledge Management: Representing, Reasoning, and Using Provenance, Trust
• Search and Optimization: Other Foundations of Search & Optimization

Application Category

• Security and Privacy: Large-scale security measurements
• Web Mining and Content Analysis: Content-based information diffusion
• Economics, Online Markets and Human Computation: Economic aspects of blockchain and cryptocurrencies

Abstract

We analyze how secure a block is after the block becomes k-deep, i.e., security-latency, for Nakamoto consensus under an exponential network delay model. We give parameter regimes for which transactions are safe when sufficiently deep in the chain. We compare our results for Nakamoto consensus under bounded network delay models and obtain analogous bounds for safety violation threshold. Next, modeling the blockchain system as a batch service queue with exponential network delay, we connect the security-latency analysis to sustainable transaction rate of the queue system. As our model assumes exponential network delay, batch service queue models give a meaningful trade-off between transaction capacity, security and latency. As adversary can attack the queue service to hamper the service process, we consider two different attacks for adversary. In an extreme scenario, we modify the selfish-mining attack for this purpose and consider its effect on the sustainable transaction rate of the queue.

Problem

• Analyzing blockchain security-latency trade-offs under network delays
• Modeling transaction capacity via batch service queue with delays
• Evaluating adversarial impact on throughput and security guarantees

Innovation

• Modeled blockchain as batch service queue system
• Analyzed security-latency trade-off with exponential delays
• Proposed k=7 confirmation rule to increase throughput