Immutable X logoImmutable X

Immutable X is a NFT-focused Validium providing zero gas fees, instant trades and scalability for applications.
Value Locked

$172.31 M

27.18%

Canonically Bridged
$172.31 M
Externally Bridged
$0.00
Natively Minted
$0.00
  • Tokens
  • Daily TPS
    1.9318.71%
  • 30D tx count
    7.17 M
  • Type
    Validium
  • Purposes
    NFT, Exchange
  • ...

    ...

    Milestones

    IMX Token introduced

    2022 Jun 29th

    Immutable announce IMX, the native ERC-20 utility token of Immutable X.

    Learn more

    Trading is live on Immutable X Marketplace

    2021 Apr 8th

    Immutable has launched the first phase of its Layer 2 scaling protocol.

    Learn more
    Risk summary
    Risk analysis
    Sequencer failureState validationData availabilityExit windowProposer failure

    State validation

    ZK proofs (ST)

    zkSTARKS are zero knowledge proofs that ensure state correctness.

    Data availability

    External (DAC)

    Proof construction relies fully on data that is NOT published on chain. There exists a Data Availability Committee (DAC) with a threshold of 5/7 that is tasked with protecting and supplying the data.

    Exit window

    None

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

    Sequencer failure

    Force via L1

    Users can force the sequencer to include a withdrawal transaction by submitting a request through L1. If the sequencer censors or is down for for more than 7d, users can use the exit hatch to withdraw their funds.

    Proposer failure

    Use escape hatch

    Users are able to trustlessly exit by submitting a Merkle proof of funds. NFTs will be minted on L1 to exit.

    Technology

    Validity proofs ensure state correctness

    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. The system state is represented using Merkle roots.

    1. Enforcing Consistency on the On-Chain State - StarkEx documentation

    Zero knowledge STARK cryptography is used

    Despite their production use zkSTARKs proof systems are still relatively new, complex and they rely on the proper implementation of the polynomial constraints used to check validity of the Execution Trace.

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

    1. STARK Core Engine Deep Dive

    Data is not stored on chain

    The balances of the users are not published on-chain, but rather sent to external trusted parties, also known as committee members. A state update is valid and accepted on-chain only if at least a quorum of the committee members sign a state update.

    • Funds can be lost if the external data becomes unavailable (CRITICAL).

    • Users can be censored if the committee restricts their access to the external data.

    1. Data Availability Modes - StarkEx documentation
    2. Validium - StarkEx documentation
    3. Availability Verifiers - StarkEx documentation
    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. Typically, the Operator is the hot wallet of the StarkEx service submitting state updates for which proofs have been already submitted and verified.

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

    1. Operator - StarkEx documentation

    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 on-chain. 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. Censorship Prevention - StarkEx documentation
    Withdrawals

    Regular exit

    The user initiates the withdrawal by submitting a regular transaction on this chain. When the block containing that transaction is proven the funds become available for withdrawal on L1. Finally the user submits an L1 transaction to claim the funds. This transaction does not require a merkle proof. When withdrawing NFTs they are minted on L1.

    1. Withdrawal - StarkEx documentation

    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 Operations - StarkEx documentation
    2. Full Withdrawal - StarkEx documentation

    Emergency exit

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

    1. Forced Operations - StarkEx documentation
    2. Full Withdrawal - StarkEx documentation
    Permissions

    The system uses the following set of permissioned addresses:

    Governor 0x9C41…EC91

    Can upgrade implementation of the system, potentially gaining access to all funds stored in the bridge. Currently there is 14d delay before the upgrade.

    Validity proof must be signed by at least 5 of these addresses to approve state update.

    SHARP Verifier Governors 0x3DE5…F5C60x21F9…AEc4

    Can upgrade implementation of SHARP Verifier, potentially with code approving fraudulent state. Currently there is 0s delay before the upgrade.

    SHARPVerifierGovernorMultisig 0x21F9…AEc4

    SHARP Verifier Governor. This is a Gnosis Safe with 2 / 3 threshold.

    SHARPVerifierGovernorMultisig participants 0x5923…85580xebc8…fD7F0x955B…2Fec

    Those are the participants of the SHARPVerifierGovernorMultisig.

    Operators 0x9B7f…927e

    Allowed to update the state. When the Operator is down the state cannot be updated.

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

    The system consists of the following smart contracts:

    This contract stores the following tokens: ETH, IMX, USDC, OMI.

    Committee 0x16BA…A295

    Data Availability Committee (DAC) contract verifying data availability claim from DAC Members (via multisig check).

    CallProxy for GpsStatementVerifier.

    SHARPVerifier 0xd51A…D8dF

    Starkware SHARP verifier used collectively by Starknet, Sorare, ImmutableX, Apex, Myria, rhino.fi and Canvas Connect. It receives STARK proofs from the Prover attesting to the integrity of the Execution Trace of these Programs including correctly computed state root which is part of the Program Output.

    FriStatementContract 0xDEf8…44fb

    Part of STARK Verifier.

    MerkleStatementContract 0x634D…804c

    Part of STARK Verifier.

    CairoBootloaderProgram 0xb4c6…6a40

    Part of STARK Verifier.

    MemoryPageFactRegistry 0x4086…70fA

    MemoryPageFactRegistry is one of the many contracts used by SHARP verifier. This one is important as it registers all necessary on-chain data.

    OldMemoryPageFactRegistry 0xFD14…D1b4

    Same as MemoryPageFactRegistry but stores facts proved by the old SHARP Verifier, used as a fallback.

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

    Escrow for ETH, IMX, USDC, OMI 0x5FDC…27e9Implementation (Upgradable)

    Main StarkEx contract, used also as an escrow.

    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