Arbitrum’s fraud proofs haven’t been used in the two years since it launched

Ed Felten, co-founder and chief scientist of Offchain Labs, which built Arbitrum, said that no evidence of fraud has been submitted on Arbitrum since the mainnet was first launched with built-in security features in August 2021.

Running as Ethereum Layer 2, Arbitrum’s interactive, multi-round Proof of fraud Works by allowing the layer 1 validator contract to decide whether a challenger’s fraud-proof submission is valid. If so, fraudulent validators’ stakes will be slashed.

A fraud proof is submitted when a challenging validator believes that another validator fraudulently or otherwise incorrectly assembled a batch of incoming transactions into the next block.

However, Felten told Cointelegraph at Korea Blockchain Week on September 4 that Arbitrum’s mainnet has yet to see fraud-proof attempts, let alone successful challenges:

“Not on mainnet. We do have one or two projects on Ethereum Proof of Work (POW). After the merger, (…) there was an Arbitrum version running on the Ethereum POW fork, and someone did try to steal all the data, And there was a successful challenge that beat it.”

Felten said there are few attempts at fraud proofing because a malicious validator could lose their entire stake.

Felten added: “If someone notices this and disputes your claim, you’re guaranteed to lose your stake, so the incentive to try is even stronger.”

Felten said there is currently a group of licensed verifiers (around 12) participating in the fraud proof game.

He also added that Arbitrum is launching a new version of fraud proof called the “BOLD” protocol (Bounded Liquidity Delay), which he said provides Arbitrum with the guarantee of responding to challenges faster.

“In the current version (…) an adversary willing to sacrifice multiple stakes can arrange to cause “N” weeks of delay (if they are willing to sacrifice “N” stakes) (…) but the BOLD protocol says not to do so regardless of their No matter how much stakes you sacrifice, they will be defeated in about eight days.”

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Arbitrum’s BOLD protocol was launched on August 4 by Offchain Labs.

Felten said Arbitrum’s fraud-proof functionality will soon be permissionless, allowing anyone to push to ensure the correctness of the chain when challenged.

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