Wide And Shallow Double-Spend Attacks On Bitcoin (+ Why Hardware Cost Is Not A Reliable Deterrent)

Joe Kelly
11 min readOct 8, 2019

This is a follow-up to my last post which was about understanding how double-spend attacks work in practice and why they matter.

tl;dr — 1) Nakamoto consensus via proof-of-work doesn’t provide meaningful assurances around double-spends. The proof-of-work your full node sees guarantees almost nothing about the finality of transactions. 2) It’s not a safe assumption that the sunk cost of ASICs (non-repurposable mining equipment) represents a fixed deterrent to

Joe Kelly