🔍 Fraud Proofs: Catch Malicious Sequencers
Learn how optimistic rollups detect and punish invalid transactions
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0 / 5 completed🛡️ Fraud Proofs: Optimistic Security
Fraud proofs are the security backbone of optimistic rollups. Unlike ZK-rollups that prove every transaction is valid, optimistic rollups assume transactions are valid unless proven otherwise. This creates a powerful challenge system where validators can dispute fraudulent state transitions.
Trust, then verify
Time to dispute
Of sequencer bond
🔍 Interactive Block Explorer: Spot the Fraud
Click on each block to examine its state transition. Can you identify which block contains fraudulent data?
🔐 The Optimistic Assumption
Assume Validity
Optimistic rollups assume all submitted state transitions are valid by default. This allows for fast processing without expensive on-chain validation.
Challenge Window
A challenge period (typically 7 days) allows anyone to dispute invalid state transitions. During this time, withdrawals are delayed.
Dispute Resolution
If fraud is detected, validators submit a fraud proof to L1. The dispute is resolved on-chain, and the malicious sequencer loses their bond.
✅ Advantages
- •Lower gas costs (no ZK proof generation)
- •EVM compatibility (easier migration)
- •Simpler technology (less cryptographic overhead)
- •Economic security through bonds
⚠️ Trade-offs
- •Long withdrawal delays (7 day challenge period)
- •Requires active validator monitoring
- •Dispute resolution can be complex
- •Security depends on at least 1 honest validator
💡 Key Insight
Fraud proofs flip the security model: instead of proving everything is correct (ZK-rollups), optimistic rollups only prove when something is wrong. This makes them more efficient but requires a waiting period for withdrawals. The system relies on economic incentives—honest validators earn rewards for catching fraud, while malicious sequencers lose their bonds.