Arbitrum Nova logoArbitrum Nova

Arbitrum Nova is an AnyTrust Optimium, differing from Arbitrum One by not posting transaction data onchain.
Value Locked

$52.63 M

4.24%

Canonically Bridged
$52.63 M
Externally Bridged
$0.00
Natively Minted
$0.00
  • Tokens
  • Daily TPS
    7.952271.27%
  • 30D tx count
    7.98 M
  • Type
    Optimium
  • Purpose
    Universal
  • ...

    Tokens

    Choose token

    Canonically Bridged Tokens (Top 15)

    Ether (ETH)
    USD Coin (USDC)
    Dai Stablecoin (DAI)
    Wrapped BTC (WBTC)
    MAGIC (MAGIC)
    SushiToken (SUSHI)
    BUSD (BUSD)
    ChainLink Token (LINK)
    Graph Token (GRT)
    Blur (BLUR)
    ApeCoin (APE)
    Livepeer Token (LPT)
    1INCH Token (1INCH)
    LoopringCoin V2 (LRC)
    StargateToken (STG)

    ...

    Milestones

    Mainnet for everyone

    2022 Aug 9th

    Whitelist got removed, there are no restrictions on who can transact with the network.

    Learn more
    Risk summary
    Fraud proof system is fully deployed but is not yet permissionless as it requires Validators to be whitelisted.
    Risk analysis
    Fraud proof system is fully deployed but is not yet permissionless as it requires Validators to be whitelisted.
    Sequencer failureState validationData availabilityExit windowProposer failure

    State validation

    Fraud proofs (INT)

    Fraud proofs allow 13 WHITELISTED actors watching the chain to prove that the state is incorrect. Interactive proofs (INT) require multiple transactions over time to resolve. There is a 6d 8h challenge period.

    Data availability

    External (DAC)

    Proof construction relies fully on data that is NOT published on chain. There exists a Data Availability Committee (DAC) with a threshold of 5/6 that is tasked with protecting and supplying the data.

    Exit window

    2d
    The Security Council can upgrade with no delay.

    Upgrades are initiated on L2 and have to go first through a 3d delay. Since there is a 1d to force a tx, users have only 2d to exit. If users post a tx after that time, they would need to self propose a root with a 6d 8h delay and then wait for the 6d 8h challenge window, while the upgrade would be confirmed just after the 6d 8h challenge window and the 3d L1 timelock.

    Sequencer failure

    Self sequence

    In the event of a sequencer failure, users can force transactions to be included in the project’s chain by sending them to L1. There is a 1d delay on this operation.

    Proposer failure

    Self propose

    Anyone can become a Proposer after 6d 8h 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. The challenge protocol can be subject to delay attacks.

    • 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).

    1. How is fraud proven - Arbitrum documentation FAQ
    2. Arbitrum Glossary: Challenge Period
    3. RollupUser.sol - Etherscan source code, onlyValidator modifier
    4. Solutions to Delay Attacks on Rollups

    Data is not stored on chain

    Users transactions are not published on-chain, but rather sent to external trusted parties, also known as committee members (DAC). Members of the DAC collectively produce a Data Availability Certificate (comprising BLS signatures from a quorum) guaranteeing that the data behind the new transaction batch will be available until the expiry period elapses (currently a minimum of two weeks). This signature is not verified by L1, however external Validators will skip the batch if BLS signature is not valid resulting. This will result in a fraud proof challenge if this batch is included in a consecutive state update. It is assumed that at least one honest DAC member that signed the batch will reveal tx data to the Validators if Sequencer decides to act maliciously and withhold the data. If the Sequencer cannot gather enough signatures from the DAC, it will “fall back to rollup” mode and by posting the full data directly to the L1 chain. The current DAC threshold is 5 out of 6.

    • Funds can be lost if the external data becomes unavailable (CRITICAL).

    • Users can be censored if the committee restricts their access to the external data.

    1. Inside AnyTrust - Arbitrum documentation
    Operator

    The system has a centralized sequencer

    While forcing transaction 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.

    1. Sequencer - Arbitrum documentation

    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 (45818 blocks) of inactivity from the currently whitelisted Proposers.

    1. SequencerInbox.sol - Etherscan source code, forceInclusion function
    2. Sequencer Isn’t Doing Its Job - Arbitrum documentation
    Withdrawals

    Regular exit

    The user initiates the withdrawal by submitting a regular transaction on this chain. 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.

    1. Transaction lifecycle - Arbitrum documentation
    2. L2 to L1 Messages - Arbitrum documentation
    3. Mainnet for everyone - Arbitrum Blog

    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.

    1. Tradeable Bridge Exits - Arbitrum documentation

    Autonomous exit

    Users can (eventually) exit the system by pushing the transaction on L1 and providing the corresponding state root. The only way to prevent such withdrawal is via an upgrade.

    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.

    1. Inside Arbitrum Nitro

    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 delay for all L2 --> L1 messages (in total a delay of 12d 8h). 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 delay on code upgrades.

    1. Arbitrum DAO
    Permissions

    The system uses the following set of permissioned addresses:

    ProxyAdmin 2 0x5613…0678

    Admin of UpgradeExecutor.

    Used in:

    Project icon
    ProxyAdmin 0x71D7…7148

    Admin of RollupEventInbox, ChallengeManager, Outbox, Bridge, Inbox.

    ProxyAdmin 3 0xa8f7…e560

    Admin of L1CustomGateway, L1ERC20Gateway, L1GatewayRouter.

    Validators/Proposers 0x0fF8…34B4

    They can submit new state roots and challenge state roots. Some of the operators perform their duties through special purpose smart contracts.

    Sequencers 0x0C59…E32D

    Central actors allowed to submit transaction batches to L1.

    SecurityCouncil 0xF06E…3F85

    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.

    Used in:

    Project icon
    BatchPosterManagerMultisig 0xd0FD…679B

    It can update whether an address is authorized to be a batch poster at the sequencer inbox. The UpgradeExecutor retains the ability to update the batch poster manager (along with any batch posters). This is a Gnosis Safe with 4 / 6 threshold.

    Used in:

    Project icon

    Those are the participants of the BatchPosterManagerMultisig.

    L1ArbitrumTimelock 0xE684…7f49

    It gives the DAO participants on the L2 the ability to upgrade the system. Only the L2 counterpart of this contract can execute the upgrades.

    Used in:

    Project icon
    Smart contracts
    A diagram of the smart contract architecture
    A diagram of the smart contract architecture

    The system consists of the following smart contracts on the host chain (Ethereum):

    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: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    Implementation used in:

    Project icon

    Contract managing Inboxes and Outboxes. It escrows ETH sent to L2. This contract stores the following tokens: ETH.

    Can be upgraded by: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    Implementation used in:

    Project icon

    Main entry point for the Sequencer submitting transaction batches to a Rollup.

    Can be upgraded by: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    Implementation used in:

    Project icon

    Entry point for users depositing ETH and sending L1 --> L2 messages. Deposited ETH is escrowed in a Bridge contract.

    Can be upgraded by: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h 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: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h 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: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    Proxy used in:

    Project icon

    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: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    Proxy used in:

    Project icon

    Router managing token <–> gateway mapping.

    Can be upgraded by: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    Implementation used in:

    Project icon

    Contract that allows challenging invalid state roots. Can be called through the RollupProxy.

    Can be upgraded by: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    OneStepProofEntry 0xC6E1…4F7e

    Contract used to perform the last step of a fraud proof.

    OneStepProverMemory 0xb602…D3ED

    Contract used to perform the last step of a fraud proof.

    OneStepProverMath 0x221C…DCAa

    Contract used to perform the last step of a fraud proof.

    OneStepProverHostIo 0xd7f1…A63e

    Contract used to perform the last step of a fraud proof.

    OneStepProver0 0xA174…A58C

    Contract used to perform the last step of a fraud proof.

    Value Locked is calculated based on these smart contracts and tokens:

    Main entry point for users depositing ERC20 tokens. Upon depositing, on L2 a generic, “wrapped” token will be minted.

    Can be upgraded by: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    Contract managing Inboxes and Outboxes. It escrows ETH sent to L2.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

    Project icon
    Escrow for DAI 0xA2e9…aAd3

    DAI Vault for custom DAI Gateway. Fully controlled by MakerDAO governance.

    Can be upgraded by: SecurityCouncil and L1ArbitrumTimelock

    Upgrade delay: 12d 8h or 0 if overridden by Security Council

    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).

    Knowledge nuggets