Optimism Bridge
Optimism bridge is the canonical smart contract to move assets from Ethereum mainnet to Optimism Layer-2 (L2). Assets are locked on mainnet and minted on Optimism.
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- Documentation
- Auditors
- Please see our FAQ on experienced auditors
- Website
- Token: OP
- Tags: Bridging
- Code reviewed by several experienced auditors including OpenZeppelin and Trail of Bits
- Public team promotes accountability
- No documented protocol hacks since launch
- Core protocol launched in 2021; maturity over one year minimizes technical risk as smart contracts are well battle-tested
- Top 5% by total value locked reduces risk
- Multisig wallet controls protocol upgrades
- Multisig consists of at least 4 signers, which means the protocol is less susceptible to centralization risks
- No timelock exists or no information documented, which mean a malicious actor could approve upgrades without any delay
- Low voting power concentration reduces risk
- No death spiral concerns
- Bridge messages are validated by smart contracts on Ethereum, thus inheriting security of the L1 network
- The Optimism Bridge is managed by the Optimism chain team, which increases how much oversight the bridge receives as it is key to the well-functioning of the Optimism chain
What is Optimism?
Optimism is a Layer-2 (L2) blockchain for the Ethereum mainnet that uses optimistic rollups as its scaling method. Rollups are a general method to scaling transactions above the means of the Layer-1 (L1) by essentially 'rolling up' all the transaction on Arbitrum into one transaction recorded on the L1 to save gas fees. Optimism is built on top of and secured by the Ethereum blockchain as it processes all transaction on its own sidechain and posts the updated chain state back to the Ethereum mainnet. The Optimism rollup is optimistic because the transactions are always assumed to be correct and validators are incentivized to submit only valid transactions. The validity of a transaction can be challenged for up to seven days.
How Optimism bridge works
The Optimism bridge allows users to transfer native (or canonical) assets directly from Ethereum to Optimism via its two-way messaging system. To use the chain, users execute a deposit transaction which transfers funds to the bridge contract on the L1 and credits the same funds to you on the Optimism L2 at the specified user address. Withdrawing back from Optimism to Ethereum involves burning the asset on L2 and subsequently releasing the locked funds on the L1.
Risks of using the Optimism bridge
Due to the inherent design of optimistic rollups, all withdrawals back to the Ethereum mainnet must wait the duration of the challenge period of seven days. The use of a centralized sequencer in the initial stages can influence transaction ordering, and if there are no honest validators, then a malicious actor can steal funds by posting invalid blocks and state commitments.