Fraud Proofs Under Real Attack Conditions

A fraud proof is useless if the required data to construct it is withheld. This is the core attack vector against optimistic rollups like Arbitrum and Optimism.

• Liveness vs. Safety: Forces a trade-off; full data publication guarantees safety but kills scalability.
• The Blob Solution: EIP-4844 proto-danksharding reduces cost but doesn't eliminate the fundamental data withholding attack.

The security of an optimistic rollup depends on at least one honest actor being funded and online to submit a fraud proof. This creates a single point of failure.

• Watchtower Incentives: Models for Altlayer and Arbitrum BOLD rely on staking rewards that may not cover attack opportunity costs.
• Time-Bound Attacks: Adversaries can coordinate attacks to overwhelm or outspend watchtowers during the challenge period.

Validity proofs (ZK-SNARKs/STARKs) shift the security burden. zkSync, Starknet, and Polygon zkEVM provide cryptographic finality without relying on network liveness.

• No Challenge Period: State updates are verified, not disputed. User withdrawals are instant.
• Hardware is the Bottleneck: Prover costs and latency are the new constraints, not social consensus.

Fraud proofs don't travel well. Bridging assets between an optimistic rollup and another chain reintroduces the full trust assumption of the bridge validator set.

• LayerZero & Wormhole: These messaging layers become critical trust points, often centralized.
• Shared Security Models: Projects like EigenLayer and Babylon attempt to re-stake economic security for interop, creating new systemic risks.

Fraud proofs require data to be available to be proven. Attackers can censor data for a single honest validator, paralyzing the system. This is the core vulnerability that Optimistic Rollups like Arbitrum and Optimism must mitigate.

• Attack Vector: Withhold state data from the one honest party.
• Result: Invalid state transitions become final, enabling theft of $10B+ TVL.
• Mitigation: Data Availability Committees (DACs) or full Ethereum calldata posting.

An attacker can spam the chain with fraudulent state updates, forcing honest validators into a continuous, costly fraud proof generation loop. This exhausts resources and creates a Denial-of-Service condition.

• Cost Asymmetry: Generating fake fraud is cheap; proving it is ~1000x more expensive in compute.
• Target: Overwhelm OP Stack sequencers or Arbitrum validators.
• Outcome: Network halts or forces expensive centralized intervention.

The 7-day challenge window is a systemic risk vector, not just a user inconvenience. It creates a massive, liquid target for market manipulation and lending protocol exploits.

• Mechanics: Attack bridge, mint infinite assets on L2, drain LayerZero or Across liquidity pools on L1 during the window.
• Amplifier: Composable DeFi (Aave, Compound) can be drained before fraud is proven.
• Reality: This window is a $Billion+ option sold to attackers.

Fraud proof systems assume at least one honest validator. In practice, validator sets trend towards re-staking pools like EigenLayer and professional operators. This creates a small, colludable set. The security model devolves to a Proof-of-Authority system.

• Entity Risk: Lido, Coinbase, Figment control critical validation roles.
• Incentive: Collusion payoff can exceed $100M+ for a single coordinated attack.
• Result: The "1-of-N honest" assumption is a social, not cryptographic, guarantee.

Fraud proofs are useless if the sequencer withholds the transaction data needed to construct them. This is the core vulnerability of optimistic rollups like Arbitrum and Optimism.\n- Solution: EigenDA, Celestia, and Avail act as external DA layers, but add complexity and latency.\n- Reality: Full data publication on L1 (Ethereum) remains the gold standard, costing ~$0.25 per tx in blobs.

Optimistic systems rely on altruistic 'watchers' to submit fraud proofs. In practice, this creates a public goods problem.\n- Why it fails: No direct profit for proving fraud, leading to apathy. A malicious sequencer could bribe watchers to stay silent.\n- Emerging Fix: Projects like Espresso Systems and Astria are building shared sequencer networks with slashing for provable malfeasance, aligning incentives.

ZK-rollups like zkSync and Starknet use validity proofs, eliminating the fraud window. But their 'prover' is a centralized bottleneck.\n- The Gap: Generating a SNARK/STARK proof for a large block can take minutes, forcing a trade-off between decentralization and finality.\n- The Frontier: Risc Zero, SP1, and Succinct Labs are racing to create generalized provers to break this bottleneck and reduce costs.

Polygon Avail is a modular DA layer built for this specific threat model. It uses data availability sampling (DAS) and KZG commitments.\n- Core Innovation: Light clients can probabilistically verify data is available without downloading the entire block.\n- Trade-off Accepted: It provides ~12s finality and cheaper DA than Ethereum, but sacrifices the shared security of L1 settlement.