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About

Metal L2 is a general-purpose OP stack rollup by Metallicus focused on banking and compliance.

Value Locked
$271.71 K4.10%
Canonically Bridged
$271.71 K
Externally Bridged
$0.00
Natively Minted
$0.00
View TVL Breakdown
  • Tokens
  • Daily UOPS
    0.010.00%
  • 30D ops count
    4.81 K
  • Stage
    Stage 0
  • Type
    Optimistic Rollup
  • Purpose
    Universal
    • Sequencer failureState validationData availabilityExit windowProposer failure

    Badges

    About

    Metal L2 is a general-purpose OP stack rollup by Metallicus focused on banking and compliance.

    Recategorisation

    179d
    10h
    22m
    58s

    The project will be classified as "Other" due to its specific risks that set it apart from the standard classifications.

    The project will move to Others because:

    The proof system isn't fully functional

    Consequence: projects without a proper proof system fully rely on single entities to safely update the state. A malicious proposer can finalize an invalid state, which can cause loss of funds.

    Learn more about the recategorisation here.

    Value Locked
    Canonical
    External
    Native
    Activity
    Metal
    Ethereum
    Onchain costs
    Calldata
    Blobs
    Compute
    Overhead
    Risk summary

    Funds can be frozen if

    1. the centralized validator goes down. Users cannot produce blocks themselves and exiting the system requires new block production (CRITICAL).

    MEV can be extracted if

    1. the operator exploits their centralized position and frontruns user transactions.
    Risk analysis
    Sequencer failureState validationData availabilityExit windowProposer failure

    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.

    State validation

    None

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

    Data availability

    Onchain

    All of the data needed for proof construction is published on Ethereum L1.

    Exit window

    None

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

    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
    MetalMetal is a
    Stage 0
    Optimistic Rollup.
    The requirement for available node software is under review

    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 not enabled

    OP Stack projects can use the OP fault proof system, already being deployed on some. This project though is not using fault proofs yet and is relying on the honesty of the permissioned Proposer and Challengers to ensure state correctness. The smart contract 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
    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

    Users can force any transaction

    Because the state of the system is based on transactions submitted on the underlying host chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract on the host chain 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:

    Challenger ConduitMultisig

    Challenger is an actor allowed to challenge or delete state roots proposed by a Proposer.

    Used in:

    Guardian (3) LivenessModuleOpFoundationOperationsSafeSecurityCouncilMultisig

    Guardian is an actor allowed to pause deposits and withdrawals.

    Proposer EOA 1

    Proposer is an actor allowed to post new state roots of the current layer to the host chain.

    Sequencer EOA 2

    Sequencer is an actor allowed to commit transactions from the current layer to the host chain.

    LivenessModule 0x0454…a748
    • Can act on behalf of SecurityCouncilMultisig.
    • A Guardian (acting via SuperchainGuardianMultisig, SecurityCouncilMultisig).
    • used to remove members inactive for 98d while making sure that the threshold remains above 75%. If the number of members falls below 8, the OpFoundationUpgradeSafe takes ownership of the multisig

    Used in:

    ConduitMultisig 0x4a49…A746
    • A Gnosis Safe with 4 / 8 threshold.
    • A Challenger.
    • Can change the configuration of SystemConfig - it can update the preconfer address, the batch submitter (Sequencer) address and the gas configuration of the system.

    Used in:

    ConduitMultisig participants (8) 0xA073…bda20xF331…647D0xF0B7…A4f00xa400…e6e40x3840…Fd5f0xa0C6…90380xefCf…dD5C0x4D80…5BAe

    Those are the participants of the ConduitMultisig.

    SuperchainProxyAdminOwner 0x5a0A…3d2A
    • A Gnosis Safe with 2 / 2 threshold.
    • Can act on behalf of ProxyAdmin, SuperchainProxyAdmin.
    • Can change the configuration of AddressManager (acting via ProxyAdmin) - set and change address mappings.
    • Can change the configuration of Lib_AddressManager (acting via SuperchainProxyAdmin) - set and change address mappings.
    • Can upgrade the implementation of OptimismMintableERC20Factory, L2OutputOracle, OptimismPortal, L1ERC721Bridge, SystemConfig (acting via ProxyAdmin).
    • Can upgrade the implementation of L1StandardBridge (acting via ProxyAdmin) - upgrading the bridge implementation can give access to all funds escrowed therein.
    • Can upgrade the implementation of SuperchainConfig (acting via SuperchainProxyAdmin).

    Used in:

    SuperchainProxyAdminOwner participants (2) OpFoundationUpgradeSafeSecurityCouncilMultisig

    Those are the participants of the SuperchainProxyAdminOwner.

    OpFoundationOperationsSafe 0x9BA6…6b3A
    • A Gnosis Safe with 5 / 7 threshold.
    • Can act on behalf of DeputyGuardianModule.
    • A Guardian (acting via SuperchainGuardianMultisig, DeputyGuardianModule).

    Used in:

    OpFoundationOperationsSafe participants (7) GnosisSafe0x3041…16230xE7dE…d02e0xBF93…a2c80x4D01…6d150x7cB0…C54f0x9bbF…31aa

    Those are the participants of the OpFoundationOperationsSafe.

    SecurityCouncilMultisig 0xc281…Bd03
    • A Gnosis Safe with 10 / 13 threshold. It uses the following modules: LivenessModule (used to remove members inactive for 98d while making sure that the threshold remains above 75%. If the number of members falls below 8, the OpFoundationUpgradeSafe takes ownership of the multisig).
    • Member of SuperchainGuardianMultisig, SuperchainProxyAdminOwner.
    • A Guardian (acting via SuperchainGuardianMultisig).

    Used in:

    SuperchainGuardianMultisig 0x09f7…dAf2
    • A Gnosis Safe with 1 / 1 threshold. It uses the following modules: DeputyGuardianModule (allows the OpFoundationOperationsSafe, called the deputy guardian, to act on behalf of the Gnosis Safe).
    • Can act as a Guardian.

    Used in:

    SuperchainGuardianMultisig participants (1) SecurityCouncilMultisig

    Those are the participants of the SuperchainGuardianMultisig.

    GnosisSafe 0x42d2…9c64
    • A Gnosis Safe with 2 / 2 threshold.
    • Member of OpFoundationUpgradeSafe, OpFoundationOperationsSafe.

    Used in:

    GnosisSafe participants (2) 0xb237…97A50x4665…7429

    Those are the participants of the GnosisSafe.

    OpFoundationUpgradeSafe 0x847B…9D92
    • A Gnosis Safe with 5 / 7 threshold.
    • Member of SuperchainProxyAdminOwner.

    Used in:

    OpFoundationUpgradeSafe participants (7) GnosisSafe0x3041…16230xE7dE…d02e0xBF93…a2c80x4D01…6d150x7cB0…C54f0x9bbF…31aa

    Those are the participants of the OpFoundationUpgradeSafe.

    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):

    L1CrossDomainMessenger 0x0a47…934DImplementation (Upgradable)

    Sends messages from host chain to this chain, and relays messages back onto host chain. In the event that a message sent from host chain to this chain is rejected for exceeding this chain’s epoch gas limit, it can be resubmitted via this contract’s replay function.

    Implementation used in:

    OptimismMintableERC20Factory 0x1aaa…8730Implementation (Upgradable)Admin

    A helper contract that generates OptimismMintableERC20 contracts on the network it’s deployed to. OptimismMintableERC20 is a standard extension of the base ERC20 token contract designed to allow the L1StandardBridge contracts to mint and burn tokens. This makes it possible to use an OptimismMintablERC20 as this chain’s representation of a token on the host chain, or vice-versa.

    Can be upgraded by:
    SuperchainProxyAdminOwner

    Upgrade delay: No delay

    Implementation used in:

    LivenessGuard 0x2442…4a25

    Implementation used in:

    ProxyAdmin 0x37Ff…AC99
    • Can be used to configure AddressManager - set and change address mappings.
    • Can be used to upgrade implementation of OptimismMintableERC20Factory, L2OutputOracle, OptimismPortal, L1ERC721Bridge, SystemConfig.
    • Can be used to upgrade implementation of L1StandardBridge - upgrading the bridge implementation can give access to all funds escrowed therein.
    L2OutputOracle 0x3B1F…1426Implementation (Upgradable)Admin

    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:
    SuperchainProxyAdminOwner

    Upgrade delay: No delay

    Implementation used in:

    OptimismPortal 0x3F37…3956Implementation (Upgradable)Admin

    The main entry point to deposit funds from host chain to this chain. It also allows to prove and finalize withdrawals. This contract stores the following tokens: ETH.

    Can be upgraded by:
    SuperchainProxyAdminOwner

    Upgrade delay: No delay

    Implementation used in:

    L1ERC721Bridge 0x50D7…4680Implementation (Upgradable)Admin

    Used to bridge ERC-721 tokens from host chain to this chain.

    Can be upgraded by:
    SuperchainProxyAdminOwner

    Upgrade delay: No delay

    Implementation used in:

    SuperchainProxyAdmin 0x543b…fB04
    • Can be used to configure Lib_AddressManager - set and change address mappings.
    • Can be used to upgrade implementation of SuperchainConfig.

    Implementation used in:

    L1StandardBridge 0x6d0f…0BF3Implementation (Upgradable)Admin

    The main entry point to deposit ERC20 tokens from host chain to this chain. This contract can store any token. This contract can store any token.

    Can be upgraded by:
    SuperchainProxyAdminOwner

    Upgrade delay: No delay

    Implementation used in:

    SystemConfig 0x7BD9…b8aAImplementation (Upgradable)Admin

    Contains configuration parameters such as the Sequencer address, gas limit on this chain and the unsafe block signer address.

    Can be upgraded by:
    SuperchainProxyAdminOwner

    Upgrade delay: No delay

    Implementation used in:

    SuperchainConfig 0x9570…4a4CImplementation (Upgradable)Admin

    Used to manage global configuration values for multiple OP Chains within a single Superchain network. The SuperchainConfig contract manages the PAUSED_SLOT, a boolean value indicating whether the Superchain is paused, and GUARDIAN_SLOT, the address of the guardian which can pause and unpause the system.

    Can be upgraded by:
    SuperchainProxyAdminOwner

    Upgrade delay: No delay

    Proxy used in:

    AddressManager 0xd4b1…3a37

    Legacy contract used to manage a mapping of string names to addresses. Modern OP stack uses a different standard proxy system instead, but this contract is still necessary for backwards compatibility with several older contracts.

    Lib_AddressManager 0xdE1F…d81F

    Legacy contract used to manage a mapping of string names to addresses. Modern OP stack uses a different standard proxy system instead, but this contract is still necessary for backwards compatibility with several older contracts.

    Implementation used in:

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

    Generic escrow 0x6d0f…0BF3Implementation (Upgradable)Admin

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

    Can be upgraded by:
    ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

    Escrow for ETH 0x3F37…3956Implementation (Upgradable)Admin

    Main entry point for users depositing ETH.

    Can be upgraded by:
    ProxyAdmin

    Upgrade delay: No delay

    Implementation used in:

    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
    Thumbnail of How Optimism compresses data

    How Optimism compresses data

    Learn more

    Thumbnail of Superchain Explainer

    Superchain Explainer

    Learn more

    Thumbnail of Modular Rollup Theory

    Modular Rollup Theory

    Learn more