By Margaux Nijkerk, CoinDesk; Translated by Tao Zhu, Golden Finance
Optimism is the leading Layer 2 blockchain designed to help Ethereum users transact quickly and with low fees. Its technology underlies some of the biggest names in the blockchain space, including Coinbase exchange’s popular Base blockchain and Worldcoin’s World Chain (built by OpenAI founder Sam Altman).
But for years, Optimism has had a problem. All blockchains using Optimism technology are built on a core underlying premise: they “borrow” Ethereum’s security apparatus. But in fact, this is not the case.
Until now, a core feature has been missing from Optimism’s security design: “fault proofs.” On Monday, this long-promised technology finally landed on Optimism’s mainnet.
Fault proofs are designed to ensure the honesty of Layer-2 chains based on Optimism. They help prevent Layer-2 chain operators from passing inaccurate transaction data to Ethereum's Layer-1 transaction ledger and provide support for the Layer-2 chain's "decentralized" withdrawal mechanism.
All Layer 2 Rollup networks use similar "proof" technology, including Optimism's competitor Arbitrum. It is designed to ensure that Rollup users (whether NFT traders, retail investors or well-known financial institutions) can trust Ethereum's vast network of operators, rather than Rollup's own internal systems, to accurately record their transactions and withdrawals.
As Layer 2 chains such as Arbitrum roll out proofs of their systems, Optimism lags behind. Over the years, this has made Optimism the target of criticism from its peers, who claim their technology is more secure and advanced.
Now that proofs of failure are finally live on Optimism’s mainnet, the network’s developers — and a growing ecosystem of other teams using its technology — are hoping to put the past behind them.
How do “proofs of failure” work?
Over the past two years, Layer 2 Rollup networks like Optimism’s have become the go-to method for running on the notoriously expensive Ethereum blockchain.
When a user submits a transaction to a Rollup network, it’s bundled with other users’ transactions before being passed to Ethereum. These bundles are written to Ethereum’s transaction ledger all at once, a setup that allows users to transact faster and for a fraction of the fees.
In theory, Rollup transactions are protected by “proofs,” a cryptographic method that allows observers on Ethereum to check that transaction details are being accurately recorded.
This is most important when it comes to withdrawals, which allows users to trust Ethereum (rather than the rollup network) to pull their funds out of the Layer 2 chain.
Without fault proofs, users who deposit funds into Optimism need to trust the rollup’s “security committee” to return the funds — a system that exposes the rollup to potential human error or bias. With fault proofs, these users only need to trust Ethereum.
Optimism, which takes its name from its “Optimism” proof system, launched a version of the technology when it first launched in 2021 but quickly scrapped it after discovering problems.
“We actually removed the entire system, redesigned it, and rewrote the entire thing,” OP Labs CEO Karl Floersch said in an interview. “It was brutal, but it was absolutely the right decision.”
The Optimism team previously shared in March that they were testing its error proof system on their Sepolia testnet. Since then, they were audited by blockchain security firm Sherlock, which found a number of bugs that they were able to patch.
“So we fixed all the issues that were found, and we feel confident that it’s ready for prime time for the actual implementation,” Floersch said.
Starting this week, the network will once again rely on the error proof system to power withdrawals, but it will still retain the “training wheels” to ensure everything runs smoothly. The safety committee will remain intact and intervene in the event that the error proof system fails. The combination of these two entities is what Optimism calls “phase one decentralization.”
The goal is to eventually achieve phase two decentralization, when the network will not have to rely on the safety committee at all.
“Phase 2 is a multi-failure proofing system that is sufficient to enable the system to operate in a certain way, such as autonomous driving. The safety board does not have the ability to intervene at the last minute,” Floersch said.
Floersch added that the team is working hard to achieve the goals of Phase 2, but he did not give a timeline for achieving this ultimate vision.
As the proofs of failure eventually make their way to Optimism’s mainnet, other blockchains using the Optimism OP Stack will also gain access to the technology. (According to DefiLlama, the two blockchains currently using the Optimism OP Stack, Blast and Base, have surpassed Optimism’s mainnet in terms of total locked value.)
“We will start with the OP mainnet for this upgrade, which is a pretty big upgrade,” Floersch noted. “However, it should not take too long for Coinbase’s Base chain to implement the proof-of-failure system,” Floersch added.
Alex
