Unit 4 · Level 2 · The multichain world
Bridge risk
A multichain world needs bridges, and bridges became crypto's most expensive crime scene. March 2022: the Ronin bridge (behind the game Axie Infinity) lost roughly $600M when attackers compromised 5 of its 9 validator keys. A month earlier, Wormhole lost about $320M to a signature-verification bug. Bridges concentrate enormous locked funds behind one piece of code or one small key set. Honeypots, in other words.
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What you get asked
Why are bridges such juicy targets for hackers?
A bridge is a vault holding everyone's deposits at once. Crack the code or the keys guarding it, and the entire pool is yours, which is why the record-setting hacks are bridge hacks.
How did the roughly $600M Ronin bridge hack of March 2022 happen?
Five keys out of nine was the whole security model, and it stayed breached for days before anyone noticed. Small key sets are a bridge's soft underbelly.
Match each item to its lesson from 2022
Nearly a billion dollars across two bridges in two months. If unit 3's bridging lesson felt theoretical, 2022 made it very concrete.
A wrapped token is an IOU, only as good as the ___ locked on the other side of the bridge.
When a bridge is drained, the wrapped tokens it issued lose their backing. Always ask what's actually behind the token in your wallet.
Given the history, what's the sane approach to bridges?
Bridge what you need, know who holds the keys, and don't park your life savings mid-span. Respect for risk beats fear of it. 🐜
The rest of this unit
Alt-L1s, bridge hacks, and the honest fight over crypto's endgame.