Arbitrum One
...
Tokens:
Milestones
Nitro Upgrade
2022 Aug 31st
Upgrade is live, introducing new architecture, increased throughput and lower fees.
Learn moreOdyssey paused
2022 Jun 29th
Due of the heavy load being put on the chain, Odyssey program got paused.
Learn moreMainnet for everyone
2021 Aug 31st
Whitelist got removed, there are no restrictions on who can transact with the network.
Learn moreKnowledge Nuggets
Description
Arbitrum One is an Optimistic Rollup that aims to feel exactly like interacting with Ethereum, but with transactions costing a fraction of what they do on L1. Centralized Sequencer receives users' transactions and regularly sends the transaction batch to mainnet Ethereum. Independent Proposers (currently whitelisted) read transaction batches from L1, execute them and submit a resulting L2 state root to L1. Any Validator (currently whitelisted) can challenge the state root within the challenge window (6d 8h 43m 36s). The challenge will result in an interactive fraud proof game that will be eventually settled by L1. As long as there is at least one honest Validator, users are guaranteed that eventually correct L2 state root will be published to L1. If Sequencer is censoring users transactions, it is possible to force the transaction via L1 queue. If no Proposer publishes L2 state root within 6d 8h 43m 36s (45818 blocks), the whitelist is dropped and anyone can take over as a new Proposer or Validator.
If you find something wrong on this page you can submit an issue or edit the information.
Risk Analysis
State validation
Fraud proofs (INT)Fraud proofs allow WHITELISTED actors watching the chain to prove that the state is incorrect. Interactive proofs (INT) require multiple transactions over time to resolve.
Data availability
On chainAll of the data needed for proof construction is published on chain.
Upgradeability
~12d 9h or no delayThere is a 12d 8h 43m 36s delay for upgrades initiated by the DAO that can be canceled by the Security Council multisig. This multisig can also upgrade with no delay.
Sequencer failure
Self sequenceIn the event of a sequencer failure, users can force transactions to be included in the L2 chain by sending them to L1. There is a 1d delay on this operation.
Proposer failure
Self proposeAnyone can become a Proposer after 6d 8h 43m 36s of inactivity from the currently whitelisted Proposers.
Technology
Fraud proofs ensure state correctness
After some period of time, the published state root is assumed to be correct. For a certain time period, one of the whitelisted actors can submit a fraud proof that shows that the state was incorrect.
Funds can be stolen if none of the whitelisted verifiers checks the published state. Fraud proofs assume at least one honest and able validator (CRITICAL).
All transaction data is recorded on chain
All executed transactions are submitted to an on chain smart contract. The execution of the rollup is based entirely on the submitted transactions, so anyone monitoring the contract can know the correct state of the rollup chain.
Operator
The system has a centralized sequencer
While proposing blocks is open to anyone the system employs a privileged sequencer that has priority for submitting transaction batches and ordering transactions.
MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.
Users can force any transaction
Because the state of the system is based on transactions submitted on-chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract directly. Anyone can become a Proposer after approximately 6d 8h 43m 36s (45818 blocks) of inactivity from the currently whitelisted Proposers.
Withdrawals
Regular exit
The user initiates the withdrawal by submitting a transaction on L2. When the block containing that transaction is finalized the funds become available for withdrawal on L1. The process of block finalization usually takes several days to complete. Finally the user submits an L1 transaction to claim the funds. This transaction requires a merkle proof.
Tradeable Bridge Exit
When a user initiates a regular withdrawal a third party verifying the chain can offer to buy this withdrawal by paying the user on L1. The user will get the funds immediately, however the third party has to wait for the block to be finalized. This is implemented as a first party functionality inside Arbitrum's token bridge.
Other considerations
EVM compatible smart contracts are supported
Arbitrum One uses Nitro technology that allows running fraud proofs by executing EVM code on top of WASM.
Funds can be lost if there are mistakes in the highly complex Nitro and WASM one-step prover implementation.
Arbitrum DAO is in charge of upgrades
Arbitrum DAO allows $ARB token holders to propose and vote on changes to the organization and the technologies it governs. The governance smart contracts are implemented on Arbitrum One rollup chain. The DAO can upgrade the Arbitrum One contracts on L2 with 3d delay and - using L2 --> L1 Governance Relay, update contracts on L1 with additional 3d delay + 6d 8h 43m 36s delay for all L2 --> L1 messages (in total a delay of 12d 8h 43m 36s). The Security Council can upgrade the contracts without any delay. It can also cancel any upgrades initiated by the DAO.
Funds can be stolen if a contract receives a malicious code upgrade. There is a 12d 8h 43m 36s delay on code upgrades.
Permissions
The system uses the following set of permissioned addresses:
The admin of all contracts in the system, capable of issuing upgrades without notice and delay. This allows it to censor transactions, upgrade bridge implementation potentially gaining access to all funds stored in a bridge and change the sequencer or any other system component (unlimited upgrade power). It is also the admin of the special purpose smart contracts used by validators. This is a Gnosis Safe with 9 / 12 threshold.
Those are the participants of the SecurityCouncil.
This contract is an admin of SequencerInbox, RollupEventInbox, Bridge, Outbox, Inbox and ChallengeManager contracts. It is owned by the Upgrade Executor.
This contract is an admin of the UpgradeExecutor contract, but is also owned by it.
This is yet another proxy admin for the three gateway contracts. It is owned by the Upgrade Executor.
Central actor allowed to set the order in which L2 transactions are executed.
They can submit new state roots and challenge state roots. Some of the operators perform their duties through special purpose smart contracts.
Smart Contracts
The system consists of the following smart contracts:
Main contract implementing Arbitrum One Rollup. Manages other Rollup components, list of Stakers and Validators. Entry point for Validators creating new Rollup Nodes (state commits) and Challengers submitting fraud proofs.
Can be upgraded by: UpgradeExecutorAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Contract managing Inboxes and Outboxes. It escrows ETH sent to L2. This contract stores the following tokens: ETH.
Can be upgraded by: ArbitrumProxyAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Main entry point for the Sequencer submitting transaction batches to a Rollup.
Can be upgraded by: ArbitrumProxyAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Entry point for users depositing ETH and sending L1 --> L2 messages. Deposited ETH is escrowed in a Bridge contract.
Can be upgraded by: ArbitrumProxyAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Arbitrum's Outbox system allows for arbitrary L2 to L1 contract calls; i.e., messages initiated from L2 which eventually resolve in execution on L1.
Can be upgraded by: ArbitrumProxyAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
This contract can upgrade the system's contracts. The upgrades can be done either by the Security Council or by the L1ArbitrumTimelock.
Can be upgraded by: UpgradeExecutorAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Timelock contract for Arbitrum DAO Governance. It gives the DAO participants the ability to upgrade the system. Only the L2 counterpart of this contract can execute the upgrades.
Can be upgraded by: UpgradeExecutorAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Router managing token <--> gateway mapping.
Can be upgraded by: GatewaysAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
TVL is calculated based on these smart contracts and tokens:
Main entry point for users depositing ERC20 tokens that require minting custom token on L2.
Can be upgraded by: GatewaysAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Main entry point for users depositing ERC20 tokens. Upon depositing, on L2 a generic, "wrapped" token will be minted.
Can be upgraded by: GatewaysAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
Contract managing Inboxes and Outboxes. It escrows ETH sent to L2.
Can be upgraded by: ArbitrumProxyAdmin
Upgrade delay: 12d 8h 43m 36s or 0 if overridden by Security Council
DAI Vault for custom DAI Gateway. Fully controlled by MakerDAO governance.
The current deployment carries some associated risks:
Funds can be stolen if a contract receives a malicious code upgrade. There is no delay on code upgrades (CRITICAL).