Reorg Scenarios: Binance Hack Edition

A Disagreement

In this tweet, you can see Ari Paul and Adam Back come to a bit of a disagreement:

A Simplistic Model

Let’s assume a very simple model where 100% of the hash power helps Binance.

A More Contentious Alternative

This would be a contentious fork and a race to be the longer chain. Overtaking with 55% of the hash power for a 100 block reorg means that it would take on average 1000 blocks (~2 weeks in this scenario). The variance on that is also fairly high, with 500 blocks and 1500 blocks being fairly common in that scenario. Even at 99%, it would take 101 blocks (~20 hours) to overtake.


There are more complicated scenarios, especially with all the offline mining equipment out there, but all of them are pretty easy to analyze. The thief can incentivize miners, so it’s a losing battle for Binance, where they’ll have to pay for each block reorganized plus whatever they lost in the theft.



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Jimmy Song

Jimmy Song

Bitcoin Educator, Developer and Entrepreneur. Book: PGP Fingerprint: C1D7 97BE 7D10 5291 228C D70C FAA6 17E3 2679 E455