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SummaryValue SecuredActivityOnchain costsLivenessMilestones & IncidentsRisk summaryRisk analysisRollup stageData availabilityState validationOperatorWithdrawalsPermissionsSmart contracts

Loopring logoLoopring

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About

Loopring is a ZK Rollup exchange protocol for trading and payments.

Value secured
$37.92 M0.39%
Canonically Bridged
$37.92 M
Natively Minted
$0.00
Externally Bridged
$0.00
View TVS Breakdown
  • Tokens
  • Past day UOPS
    0.010.00%
  • 30D ops count
    31.87 K
  • Stage
  • Type
    ZK Rollup
  • Purposes
    NFT, Exchange
    • Sequencer failureState validationData availabilityExit windowProposer failure
    Explore more in Discovery UI

    Badges

    About

    Loopring is a ZK Rollup exchange protocol for trading and payments.

    Value Secured

    2024 May 23 — 2025 May 23

    Total value securedTotal
    $37.92 M0.39%
    Canonically BridgedCanonically Bridged ValueCanonical
    $37.92 M0.39%
    Natively MintedNatively Minted TokensNative
    $0.000.00%
    Externally BridgedExternally Bridged ValueExternal
    $0.000.00%
    View TVS breakdown
    Activity

    2024 May 23 — 2025 May 22

    Onchain costs

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

    2024 May 23 — 2025 May 22

    1 year total cost
    $120.44 K
    Avg cost per L2 UOP
    $0.207950
    Liveness

    The chart illustrates how "live" the project's operators are by displaying how frequently they submit transactions of the selected type and if these intervals deviate from their typical schedule.

    2025 Apr 23 — May 23

    30D avg. proof subs. interval
    1 hour
    30D avg. state updates interval
    1 hour
    Past 30 days anomalies
    Milestones & Incidents

    DeFi Port is Live on Loopring

    2022 Sep 27th

    Dutch auctions, lending, and other DeFi functions can be performed on Loopring.

    Learn more

    Loopring Supports NFTs

    2021 Aug 24th

    Loopring supports NFT minting, trading, and transfers.

    Learn more
    Risk summary

    Funds can be lost if

    1. the proof system is implemented incorrectly.

    Users can be censored if

    1. the operator refuses to include their transactions. However, there exists a mechanism to independently exit the system.

    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
    Force via L1

    Users can force the sequencer to include a withdrawal transaction by submitting a request through L1 with a 0.02 ETH fee. If the sequencer is down for more than 15d, users can use the exit hatch to withdraw their funds. The sequencer can censor individual deposits, but in such case after 15d users can get their funds back.

    State validation
    ZK proofs (SN)

    SNARKs are zero knowledge proofs that ensure state correctness, but require trusted setup.

    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
    Use escape hatch

    Users are able to trustlessly exit by submitting a Merkle proof of funds.

    Rollup stageLoopringLoopring is a
    Stage 0
    Appchain
    ZK Rollup.

    Rollup operators cannot compromise the system, but being application-specific might bring additional risk.

    Loopring provides an orderbook decentralized exchange for spot trading. Arbitrary contracts are not supported.

    Note:
    We're still in the process of formalizing how to properly integrate appchains in the Stages framework.

    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 onchain

    All the data that is used to construct the system state is published onchain in the form of cheap calldata. This ensures that it will always be available when needed.

    1. Introduction - Loopring design doc
    Learn more about the DA layer here: Ethereum logoEthereum
    State validation

    Each update to the system state must be accompanied by a ZK proof that ensures that the new state was derived by correctly applying a series of valid user transactions to the previous state. These proofs are then verified on Ethereum by a smart contract.

    ZK Circuits

    Loopring utilizes Groth16 for their proving system. The source code of the circuits can be found here.

    • Funds can be lost if the proof system is implemented incorrectly.

    Verification Keys Generation

    Groth16 requires a circuit specific trusted setup, so they run their own ceremony. The first phase is run using Powers of Tau ceremony. Some of the instructions on how to regenerate the verification keys can be found here.

    Validity proofs

    Each update to the system state must be accompanied by a ZK proof that ensures that the new state was derived by correctly applying a series of valid user transactions to the previous state. These proofs are then verified on Ethereum by a smart contract.

    1. Operators - Loopring design doc
    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. ExchangeV3.sol#L315-L322 - Etherscan source code, submitBlocks function
    2. LoopringIOExchangeOwner.sol#L123-L126 - Etherscan source code, hasAccessTo function call

    Users can force exit the system

    Force exit allows the users to escape censorship by withdrawing their funds. The system allows users to force the withdrawal of funds by submitting a request directly to the contract onchain. The request must be served within a defined time period. If this does not happen, the system will halt regular operation and permit trustless withdrawal of funds.

    • Users can be censored if the operator refuses to include their transactions. However, there exists a mechanism to independently exit the system.

    1. Forced Withdrawals - Loopring design doc
    2. Forced Request Handling - Loopring design doc
    Withdrawals

    Regular exit

    The user initiates the withdrawal by submitting a regular transaction on this chain. When the block containing that transaction is settled the funds become available for withdrawal on L1.ZK proofs are required to settle blocks. Finally the user submits an L1 transaction to claim the funds.

    1. Withdraw - Loopring design doc

    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. Once the force operation is submitted and if the request is serviced, the operation follows the flow of a regular exit.

    1. Forced Request Handling - Loopring design doc
    2. ExchangeV3.sol#L8118 - Loopring source code, forceWithdraw function

    Emergency exit

    If the 15d deadline passes and the forced exit is still ignored the user can put the system into Withdrawal Mode, disallowing further state updates. In that case everybody can withdraw by submitting a merkle proof of their funds with their L1 transaction.

    1. Forced Request Handling - Loopring design doc
    2. ExchangeV3.sol#L8159 - Loopring source code, withdrawFromMerkleTree function
    Permissions
    A dashboard to explore contracts and permissions
    Go to Disco
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    Disco UI BannerExplore in Disco

    Ethereum

    Actors:

    LoopringMultisig 0xDd2A…9c97
    • A Multisig with 4/6 threshold. This address is the owner of the following contracts: LoopringIOExchangeOwner, ExchangeV3 (proxy), BlockVerifier, AgentRegistry, LoopringV3. This allows it to grant access to submitting blocks, arbitrarily change the forced withdrawal fee, change the Verifier address and upgrade ExchangeV3 implementation potentially gaining access to all funds in DefaultDepositContract.

    Participants (6):

    0x0F02…04380x576a…AB980x88f8…F1910x3b1D…d5F10x7414…baa90x1F28…B3D1
    RollupOwner 0x153C…8512

    The rollup owner can submit blocks, set rollup parameters and shutdown the exchange.

    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

    ExchangeV3 0x0BAB…1eA4Implementation (Upgradable)Admin

    Main Loopring contract.

    Can be upgraded by:
    LoopringMultisig with no delay
    LoopringIOExchangeOwner 0x153C…8512

    Contract used by the Prover to submit exchange blocks with zkSNARK proofs that are later processed and verified by the BlockVerifier contract. It allows to give or revoke permissions to submit blocks and to open block submission to everyone.

    DefaultDepositContract 0x674b…Bd3f

    ERC 20 token basic deposit contract. Handles user deposits and withdrawals.

    • This contract can store any token.
    LoopringV3 0xe56D…0C71

    Contract managing LRC staking for exchanges (one Loopring contract can manage many exchanges). It also allows to change the forced withdrawal fee and the Verifier address.

    FastWithdrawalAgent 0xec3C…8a31

    Auxiliary contract allowing users to process fast withdrawals.

    ForcedWithdrawalAgent 0x52ea…4470

    Auxiliary contract able to force withdrawals from L1 on behalf of users.

    BlockVerifier 0x6150…01ef

    zkSNARK Verifier based on ethsnarks library.

    Can be upgraded by:
    LoopringMultisig with no delay
    AgentRegistry 0x39B9…ea14

    Agent registry that is used by all other Loopring contracts. Currently used are FastWithdrawalAgent, ForcedWithdrawalAgent, DestroyableWalletAgent and a number of LoopringAmmPool contracts.

    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).