Base logoBase

Base is an Optimistic Rollup that has been developed on the Ethereum network, utilizing OP Stack technology.
Value Locked

$5.37 B

0.31%

Canonically Bridged
$1.46 B
Externally Bridged
$3.09 M
Natively Minted
$3.90 B
  • Tokens
  • Daily TPS
    31.079.11%
  • 30D tx count
    70.01 M
  • Stage
    Stage 0
  • Type
    Optimistic Rollup
  • Purpose
    Universal
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    Milestones

    Base starts using blobs

    2024 Mar 14th

    Base starts publishing data to blobs.

    Learn more

    Base Mainnet Launch

    2023 Jul 13th

    Base is live on mainnet.

    Learn more
    Risk summary
    Fraud proof system is currently under development. Users need to trust the block proposer to submit correct L1 state roots.
    Risk analysis
    Fraud proof system is currently under development. Users need to trust the block proposer to submit correct L1 state roots.
    Sequencer failureState validationData availabilityExit windowProposer failure

    State validation

    In development

    Currently the system permits invalid state roots. More details in project overview.

    Data availability

    On chain

    All of the data needed for proof construction is published on chain.

    Exit window

    None

    There is no window for users to exit in case of an unwanted upgrade since contracts are instantly upgradable.

    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 12h delay on this operation.

    Proposer failure

    Cannot withdraw

    Only the whitelisted proposers can publish state roots on L1, so in the event of failure the withdrawals are frozen.

    Rollup stage
    BaseBase is a
    Stage 0
    Optimistic Rollup.
    Learn more about Rollup stages
    Please keep in mind that these stages do not reflect rollup security, this is an opinionated assessment of rollup maturity based on subjective criteria, created with a goal of incentivizing projects to push toward better decentralization. Each team may have taken different paths to achieve this goal.
    Technology

    Fraud proofs are in development

    Ultimately, OP stack chains will use interactive fraud proofs to enforce state correctness. This feature is currently in development and the system permits invalid state roots.

    • Funds can be stolen if an invalid state root is submitted to the system (CRITICAL).

    1. L2OutputOracle.sol - Etherscan source code, deleteL2Outputs function

    All data required for proofs is published on chain

    All the data that is used to construct the system state is published on chain in the form of cheap blobs or calldata. This ensures that it will be available for enough time.

    1. Derivation: Batch submission - OP Mainnet specs
    2. BatchInbox - Etherscan address
    3. OptimismPortal.sol - Etherscan source code, depositTransaction function
    State derivation
    Node software

    The rollup node is composed of two software components: op-node, implementing consensus related logic, and op-geth, implementing execution logic. The configuration file can be found here.

    Compression scheme

    Data batches are compressed using the zlib algorithm with best compression level.

    Genesis state

    The genesis file can be found here.

    Data format

    The format specification of Sequencer’s data batches can be found here.

    Operator

    The system has a centralized operator

    The operator is the only entity that can propose blocks. A live and trustworthy operator is vital to the health of the system.

    • MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.

    1. L2OutputOracle.sol - Etherscan source code, CHALLENGER address
    2. L2OutputOracle.sol - Etherscan source code, PROPOSER address
    3. Decentralizing the sequencer - OP Stack docs

    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.

    1. Sequencing Window - OP Mainnet Specs
    2. OptimismPortal.sol - Etherscan source code, depositTransaction function
    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 takes a challenge period of 7d to complete. Finally the user submits an L1 transaction to claim the funds. This transaction requires a merkle proof.

    • Funds can be frozen if the centralized validator goes down. Users cannot produce blocks themselves and exiting the system requires new block production (CRITICAL).

    1. OptimismPortal.sol - Etherscan source code, proveWithdrawalTransaction function
    2. OptimismPortal.sol - Etherscan source code, finalizeWithdrawalTransaction function
    3. L2OutputOracle.sol - Etherscan source code, PROPOSER check

    Forced exit

    If the user experiences censorship from the operator with regular exit they can submit their withdrawal requests directly on L1. The system is then obliged to service this request or halt all withdrawals, including forced withdrawals from L1 and regular withdrawals initiated on L2. Once the force operation is submitted and if the request is serviced, the operation follows the flow of a regular exit.

    1. Forced withdrawal from an OP Stack blockchain
    Other considerations

    EVM compatible smart contracts are supported

    OP stack chains are pursuing the EVM Equivalence model. No changes to smart contracts are required regardless of the language they are written in, i.e. anything deployed on L1 can be deployed on L2.

    1. Introducing EVM Equivalence
    Permissions

    The system uses the following set of permissioned addresses:

    ProxyAdmin 0x0475…059E

    Owner of AddressManager. Admin of OptimismPortal, SystemConfig, L2OutputOracle, L1ERC721Bridge, OptimismMintableERC20Factory, L1StandardBridge.

    Sequencer 0x5050…76C9

    Central actor allowed to commit L2 transactions to L1.

    Proposer 0x6422…52c5

    Central actor allowed to post new L2 state roots to L1.

    Challenger 0x6F8C…7824

    Central actor allowed to delete L2 state roots proposed by a Proposer.

    Guardian 0x1453…E056

    Central actor allowed to pause deposits and withdrawals.

    AdminMultisig 0x7bB4…595c

    This address is the owner of the ProxyAdmin. It can upgrade the bridge implementation potentially gaining access to all funds. This is a Gnosis Safe with 2 / 2 threshold.

    AdminMultisig participants 0x9855…46A10x9BA6…6b3A

    Those are the participants of the AdminMultisig.

    GuardianMultisig 0x1453…E056

    Address designated as a Guardian of the OptimismPortal, meaning it can halt withdrawals. It’s the owner of SystemConfig, which allows to update the sequencer address. Moreover, it can challenge state roots without going through the fault proof process. This is a Gnosis Safe with 3 / 8 threshold.

    Those are the participants of the GuardianMultisig.

    BaseMultisig 0x9855…46A1

    Core multisig of the Base team, it’s a member of the AdminMultisig, meaning it can upgrade the bridge implementation potentially gaining access to all funds. This is a Gnosis Safe with 3 / 6 threshold.

    Those are the participants of the BaseMultisig.

    OptimismMultisig 0x9BA6…6b3A

    Core multisig of the Optimism team, it can challenge state roots without going through the fault proof process. It’s also a member of the AdminMultisig, meaning it can upgrade the bridge implementation potentially gaining access to all funds. This is a Gnosis Safe with 5 / 7 threshold.

    Those are the participants of the OptimismMultisig.

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

    The system consists of the following smart contracts:

    The L2OutputOracle contract contains a list of proposed state roots which Proposers assert to be a result of block execution. Currently only the PROPOSER address can submit new state roots.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    The OptimismPortal contract is the main entry point to deposit funds from L1 to L2. It also allows to prove and finalize withdrawals. This contract stores the following tokens: ETH.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    It contains configuration parameters such as the Sequencer address, the L2 gas limit and the unsafe block signer address.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    The L1CrossDomainMessenger (L1xDM) contract sends messages from L1 to L2, and relays messages from L2 onto L1. In the event that a message sent from L1 to L2 is rejected for exceeding the L2 epoch gas limit, it can be resubmitted via this contract’s replay function.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    The L1StandardBridge contract is the main entry point to deposit ERC20 tokens from L1 to L2. This contract can store any token.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    The L1ERC721Bridge contract is the main entry point to deposit ERC721 tokens from L1 to L2.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Challenger1of2 0x6F8C…7824

    This contract is the permissioned challenger of the system. It can delete non finalized roots without going through the fault proof process. It is functionally equivalent to a 1/2 multisig where neither party can remove the other’s permission to execute a Challenger call. It is controlled by the GuardianMultisig and the OptimismMultisig.

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

    Main entry point for users depositing ERC20 token that do not require custom gateway.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    Main entry point for users depositing ETH.

    Can be upgraded by: ProxyAdmin

    Upgrade delay: No delay

    wstETH Vault for custom wstETH Gateway. Fully controlled by Lido 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).

    Knowledge nuggets
    If you find something wrong on this page you can submit an issue or edit the information