Computational cryptography › Live on mainnet today
Trust or structural assumption

≥ 1 honest challenger

In plain words

Not math: optimistic rollups assume someone honest is watching and will challenge a false claim in time.

Why it matters: If nobody challenges, a false claim goes through.

The details

On the map: disputes a bad claim within the window (not cryptographic)

Optimistic rollups post state claims to Ethereum without proving them. During a challenge window, usually about a week, anyone can dispute a false claim with a fault proof[1].

The security assumption is that at least one honest party is watching, able to submit a challenge in time and can't be censored long enough. It isn't cryptographic: if nobody challenges, a false claim is accepted.

Rests on

If any of these breaks, this breaks too.

If it falls

If this breaks, these break with it.

References

  1. Harry Kalodner, Steven Goldfeder, Xiaoqi Chen et al. Arbitrum: Scalable, private smart contracts. USENIX Security 2018. usenix.org/conference/usenixsecurity18/presentation/kalodner