Summary Value Secured Activity Onchain costs Risk summary Risk analysis Rollup stage Technology Operator Withdrawals Other considerations Permissions Smart contracts Knowledge nuggets

Metal

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About

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

Value securedTVS

$504.48 K13.7%

Canonically BridgedCanonical

$504.48 K

Externally BridgedExternal

$0.00

Natively MintedNative

$0.00

View TVS Breakdown

Tokens

Daily UOPS

0.02104%

30D ops count

28.90 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.

Metal

Recategorisation

149d

04h

24m

27s

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 Secured

Canonical

External

Native

Onchain costs

Calldata

Blobs

Compute

Overhead

Risk summary

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 can be up to 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

Metal 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).

L2OutputOracle.sol - 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.

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.

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.

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).

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.

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.

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) LivenessModule OpFoundationOperationsSafe SecurityCouncilMultisig

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 / 9 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.

Participants (9):

0x5093…6628 0xA073…bda2 0xF331…647D 0xF0B7…A4f0 0xa400…e6e4 0x3840…Fd5f 0xa0C6…9038 0xefCf…dD5C 0x4D80…5BAe

Used in:

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).

Participants (2):

OpFoundationUpgradeSafe SecurityCouncilMultisig

Used in:

OpFoundationOperationsSafe 0x9BA6…6b3A

A Gnosis Safe with 5 / 7 threshold.
Can act on behalf of DeputyGuardianModule.
A Guardian (acting via SuperchainGuardianMultisig, DeputyGuardianModule).

Participants (7):

GnosisSafe 0x3041…1623 0xE7dE…d02e 0xBF93…a2c8 0x4D01…6d15 0x7cB0…C54f 0x9bbF…31aa

Used in:

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).

Participants (13):

0x07dC…d073 0x0a12…58b8 0x1822…925e 0x4A73…e61E 0x51aC…3dDa 0x5C0F…C47e 0x6323…c865 0x74FA…B310 0x7ed8…9E39 0x8Afe…0EA4 0x9Eb1…fD7A 0xbfA0…E0d9 0xE895…E514

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.

Participants (1):

SecurityCouncilMultisig

Used in:

GnosisSafe 0x42d2…9c64

A Gnosis Safe with 2 / 2 threshold.
Member of OpFoundationUpgradeSafe, OpFoundationOperationsSafe.

Participants (2):

0xb237…97A5 0x4665…7429

Used in:

OpFoundationUpgradeSafe 0x847B…9D92

A Gnosis Safe with 5 / 7 threshold.
Member of SuperchainProxyAdminOwner.

Participants (7):

GnosisSafe 0x3041…1623 0xE7dE…d02e 0xBF93…a2c8 0x4D01…6d15 0x7cB0…C54f 0x9bbF…31aa

Used in:

EOA 1 0xC818…F1F6

A Proposer.

EOA 2 0xC94C…1B8B

A Sequencer.

Smart contracts

A diagram of the smart contract architecture

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

L1CrossDomainMessenger 0x0a47…934D Implementation (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…8730 Implementation (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…1426 Implementation (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…3956 Implementation (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…4680 Implementation (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…0BF3 Implementation (Upgradable)Admin

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

Can be upgraded by:

SuperchainProxyAdminOwner

Upgrade delay: No delay

Implementation used in:

SystemConfig 0x7BD9…b8aA Implementation (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…4a4C Implementation (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

Implementation used in: