Arbitrum Bridge is the canonical smart contract to move assets to and from the Arbitrum Layer-2 (L2) network. Assets are locked on the source chain and minted on Arbitrum.

Bridge

Arbitrum Bridge

Protocol Code Quality

Protocol Maturity

Protocol Design

Risk Rating

yellow

Average

* [Documentation](https://developer.offchainlabs.com/docs/bridging_assets)

Exploit/Hacks

Unknown

* [Website](https://bridge.arbitrum.io/)  
 * Tags: Bridge

Info

Key Metrics

Information


- Code reviewed by at least one experienced auditor; Trail of Bits audited but report is not public
- Public team promotes accountability
- No documented protocol hacks since launch

green


- Core protocol launched in 2021; maturity less than 1 year increases technical risk as smart contracts are less battle-tested
- Top 1% by total value locked reduces risk
- Centralized governance increases risk
- Low voting power concentration reduces risk


- No concerns identified
- Natively verified bridge that relies on the chain's own verifiers for bridging, and is considered the most trustless system
- The Arbitrum Bridge is managed by the Arbitrum chain team, which increases how much oversight the bridge receives as it is key to the well-functioning of the Arbitrum chain

Risk Assessment

The Arbitrum bridge has the ability to send messages between the Layer-1 (Ethereum mainnet) and Layer-2 (Arbitrum network), which allows for trustless moving of assets between the two networks.

What we like

Arbitrum currently uses a centralized sequencer that is operated by Offchain Labs. It has the ability to control the ordering of transactions which could lead to the sequencer front-running transactions and profiting at the user's expense.

What we like less

The Arbitrum canonical bridge is one of the safest bridges for you to transfer your crypto assets from Ethereum to Arbitrum in a simple and relatively fast manner.

What it means for you

Summary

#### What is Arbitrum?
Arbitrum 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. Arbitrum 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 Arbitrum 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 Arbitrum bridge works
The Arbitrum bridge allows users to transfer native (or canonical) assets directly from Ethereum to Arbitrum 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 Arbitrum L2 at the specified user address. Withdrawing back from Arbitrum to Ethereum involves burning the asset on L2 and subsequently releasing the locked funds on the L1.
#### Risks of using the Arbitrum 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.