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SummaryValue SecuredActivityOnchain costsLivenessRisk summaryRisk analysisRollup stageData availabilityState validationOperatorWithdrawalsOther considerationsPermissionsSmart contracts

Hemi logoHemi

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About

Hemi is an OP Stack based L2 on Ethereum focusing on interoperability with the Bitcoin blockchain. In addition to the EVM, Hemi uses Hemi Virtual Machine (hVM), an EVM upgraded to have awareness of the Bitcoin state.

  • Total Value SecuredTVS
    $6.40 M18.1%
  • Past day UOPSDaily UOPS
    0.044.35%
  • Gas token
    ETH
  • Type
    Other
  • Purposes
    Universal, Bitcoin DApps
  • Chain ID
    43111

    • Tokens breakdown

    Value secured breakdown

    View TVS breakdown
    Sequencer failureState validationData availabilityExit windowProposer failure
    Explore more in Discovery UI

    Badges

    About

    Hemi is an OP Stack based L2 on Ethereum focusing on interoperability with the Bitcoin blockchain. In addition to the EVM, Hemi uses Hemi Virtual Machine (hVM), an EVM upgraded to have awareness of the Bitcoin state.

    Why is the project listed in others?

    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

    2024 Sep 10 — 2025 Jul 22

    Total value securedTotal
    $6.40 M18.1%
    Canonically BridgedCanonically Bridged ValueCanonical
    $6.40 M18.1%
    Natively MintedNatively Minted TokensNative
    $0.000.00%
    Externally BridgedExternally Bridged ValueExternal
    $0.000.00%
    View TVS breakdown
    Activity

    2024 Sep 09 — 2025 Jul 21

    Onchain costs

    The section shows the operating costs that L2s pay to Ethereum.

    2024 Sep 09 — 2025 Jul 21

    1 year total cost
    $41.22 K
    Avg cost per L2 UOP
    $0.041569
    1 year data posted
    2.06 GiB
    Avg size per L2 UOP
    2.18 KiB
    Liveness

    This section shows how "live" the project's operators are by displaying how frequently they submit transactions of the selected type. It also highlights anomalies - significant deviations from their typical schedule.

    No ongoing anomalies detected

    2025 Jun 22 — Jul 22

    30D avg. tx data subs. interval
    16 minutes
    30D avg. state updates interval
    23 minutes
    Past 30 days anomalies
    Risk summary

    Funds can be stolen if

    1. a contract receives a malicious code upgrade. There is no delay on code upgrades (CRITICAL),
    2. an invalid state root is submitted to the system (CRITICAL).

    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 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 stageHemiHemi is not even a
    Stage 0
    project.

    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.
    Data availability

    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 - address
    3. OptimismPortal.sol - source code, depositTransaction function
    Learn more about the DA layer here: Ethereum logoEthereum
    State validation
    No state validation

    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 - source code, deleteL2Outputs 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 - source code, CHALLENGER address
    2. L2OutputOracle.sol - 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 - source code, depositTransaction function
    Withdrawals

    Regular messaging

    The user initiates L2->L1 messages by submitting a regular transaction on this chain. When the block containing that transaction is settled, the message becomes available for processing on L1. The process of block finalization takes a challenge period of 1d to complete.

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

    Forced messaging

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

    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
    A dashboard to explore contracts and permissions
    Go to Disco
    Disco UI Banner
    Disco UI BannerExplore in Disco

    Ethereum

    Roles:

    Challenger EOA 1

    Allowed to challenge or delete state roots proposed by a Proposer.

    Guardian EOA 1

    Allowed to pause withdrawals. In op stack systems with a proof system, the Guardian can also blacklist dispute games and set the respected game type (permissioned / permissionless).

    Proposer 0x2BD4…659e

    Allowed to post new state roots of the current layer to the host chain.

    Sequencer 0x6511…2e7A

    Allowed to commit transactions from the current layer to the host chain.

    Actors:

    GnosisSafe 0x8434…Ea69

    A Multisig with 3/8 threshold.

    • Can upgrade with no delay
      • OptimismMintableERC20Factory
      • SuperchainConfig
      • OptimismPortal
      • SystemConfig
      • L1StandardBridge
      • L2OutputOracle
      • L1ERC721Bridge
      • L1CrossDomainMessenger
    • Can interact with AddressManager
      • set and change address mappings

    Participants (8):

    0xdFd8…61d40x3dAd…2CD90xce1a…b04c0xB862…2A770x5cCf…50910xAd43…76100x9aCa…6FFa0xb972…C85b
    EOA 1 0xc0E7…cdDF
    • Can interact with SystemConfig
      • it can update the preconfer address, the batch submitter (Sequencer) address and the gas configuration of the system
    • A Challenger - acting directly
    • A Guardian - acting directly
    Smart contracts
    A dashboard to explore contracts and permissions
    Go to Disco
    Disco UI Banner
    Disco UI BannerExplore in Disco
    A diagram of the smart contract architecture
    A diagram of the smart contract architecture

    Ethereum

    OptimismPortal 0x39a0…4D7eImplementation (Upgradable)Admin

    The main entry point to deposit funds from host chain to this chain. It also allows to prove and finalize withdrawals.

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
      • guardian: EOA 1
    • This contract stores the following tokens: ETH.
    Can be upgraded by:
    GnosisSafe with no delay
    SystemConfig 0x5ae6…03c3Implementation (Upgradable)Admin

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

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
      • batcherHash: EOA 3
      • owner: EOA 1
    Can be upgraded by:
    GnosisSafe with no delay
    L2OutputOracle 0x6daF…0d51Implementation (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.

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
      • challenger: EOA 1
      • proposer: EOA 2
    Can be upgraded by:
    GnosisSafe with no delay
    SuperchainConfig 0x1514…2aB8Implementation (Upgradable)Admin

    This is NOT the shared SuperchainConfig contract of the OP stack Superchain but rather a local fork. It manages the PAUSED_SLOT, a boolean value indicating whether the local chain is paused, and GUARDIAN_SLOT, the address of the guardian which can pause and unpause the system.

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
      • guardian: EOA 1
    Can be upgraded by:
    GnosisSafe with no delay
    L1StandardBridge 0x5eaa…191eImplementation (Upgradable)Admin

    The main entry point to deposit ERC20 tokens from host chain to this chain.

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
    • This contract can store any token.
    Can be upgraded by:
    GnosisSafe with no delay
    L1ERC721Bridge 0xa446…edE0Implementation (Upgradable)Admin

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

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
    Can be upgraded by:
    GnosisSafe with no delay
    L1CrossDomainMessenger 0xF005…b050Implementation (Upgradable)Admin

    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.

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
    Can be upgraded by:
    GnosisSafe with no delay
    OptimismMintableERC20Factory 0x0262…342CImplementation (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 OptimismMintableERC20 as this chain’s representation of a token on the host chain, or vice-versa.

    • Roles:
      • admin: ProxyAdmin; ultimately GnosisSafe
    Can be upgraded by:
    GnosisSafe with no delay
    ProxyAdmin 0xbE81…FB30
    • Roles:
      • owner: GnosisSafe

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

    Generic escrow 0x5eaa…191eImplementation (Upgradable)Admin

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

    Can be upgraded by:
    ProxyAdmin with no delay
    Escrow for ETH 0x39a0…4D7eImplementation (Upgradable)Admin

    Main entry point for users depositing ETH.

    Can be upgraded by:
    ProxyAdmin with no delay

    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).