ECE Seminar: Fundamental Limits of Blockchain

Nov 27

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Monday, November 27, 2023 – 12:00PM to 1:00PM

Dongning Guo


Dongning Guo, Northwestern University

Blockchain technologies have revolutionized our understanding of consensus and decentralized trust. In this talk, I will explain the fundamental challenge of reaching consensus on a distributed ledger in the presence of adversaries and network delays. I will then use a pair of closed-form "finite-blocklength" achievability and converse theorems to answer the following questions about the Nakamoto consensus protocol: What fraction of mining power must be honest for transactions to be eventually safe? Assuming a given sufficient majority of honest mining, how deep must transactions be in a blockchain to satisfy a given safety threshold? I will also discuss the practical implications of these theorems on the fundamental trade-off between transaction throughput, confirmation latency, and safety.