Polygon Hermez logoPolygon Hermez

Hermez is an open-source ZK Rollup that aims to be optimized for secure, low-cost and usable token transfers on the wings of Ethereum.
This project is archived.
Value Locked

$319.67 K

7.29%

Canonically Bridged
$319.67 K
Externally Bridged
$0.00
Natively Minted
$0.00
  • Tokens
  • Daily TPS
    Coming soon
  • 30D tx count
    Coming soon
  • Type
    ZK Rollup
  • Purpose
    Payments
  • ...

    Risk summary
    Hermez and Polygon have recently merged. Hermez and Polygon Hermez are two names for the same rollup.
    Risk analysis
    Hermez and Polygon have recently merged. Hermez and Polygon Hermez are two names for the same rollup.
    Sequencer failureState validationData availabilityExit windowProposer failure

    State validation

    ZK proofs (SN)

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

    Data availability

    On chain

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

    Exit window

    7d

    Users have 7d to exit funds in case of an unwanted upgrade. There is a 7d delay before an upgrade is applied, and withdrawals can take up to 0s to be processed.

    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 , users can use the exit hatch to withdraw their funds.

    Proposer failure

    Self propose

    If the Proposer fails, users can leverage the source available prover to submit proofs to the L1 bridge.

    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.

    1. ZK proofs - Hermez documentation

    Zero knowledge SNARK cryptography is used

    Despite their production use zkSNARKs are still new and experimental cryptography. Cryptography has made a lot of advancements in the recent years but all cryptographic solutions rely on time to prove their security. In addition zkSNARKs require a trusted setup to operate.

    • Funds can be stolen if the cryptography is broken or implemented incorrectly.

    1. ZK proofs - Hermez documentation
    2. Multi-party Computation for the Trusted Setup - Hermez documentation

    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 calldata. This ensures that it will always be available when needed.

    1. Data Availability - Hermez documentation
    Operator

    There is no central operator

    The system runs an auction in which anyone can bid to become the operator for a set number of blocks. The operator will be able to propose blocks and collect fees during this window. Hermez will also run a operator known as boot coordinator that will propose blocks in case no one bids in the auction. This operator can be removed by the governance.

    1. Forging Consensus Protocol - Hermez documentation
    2. Boot Coordinator - Hermez documentation

    Users can force any transaction

    Because the block production is open to anyone if users experience censorship from the operator they can propose their own blocks which would include their transactions.

    • Users can be censored if the operator refuses to include their transactions and users lack resources to propose blocks themselves.

    1. Can coordinators censor transactions? - Hermez 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 requires a merkle proof. This operation cannot be performed if the withdrawal exceeds certain threshold.

    1. Withdrawing Funds from Hermez - Hermez documentation

    Forced withdraw

    The user submits the withdrawal request on L1. This forces the operators to pick up the request before other L2 transactions. A block still needs to be proved, the user still submits a merkle proof, and the funds threshold still cannot be exceeded.

    1. Force Exit - Hermez documentation

    Delayed withdraw

    When the user does a regular or forced withdraw and their funds exceed a certain threshold a timer activates. After a specified time has passed and the emergency mode has not been activated the funds can be withdrawn.

    1. Withdrawal Delayer Mechanism - Hermez documentation

    Emergency mode

    When the user does a regular or forced withdraw and their funds exceed a certain threshold a timer activates. The operators can now trigger emergency mode and transfer the user’s funds to the governance.

    • Funds can be stolen if the operators trigger a false alarm during withdrawal (CRITICAL).

    1. Withdrawal Delayer Mechanism - Hermez documentation
    Smart contracts

    The system consists of the following smart contracts:

    This contract can store any token.

    ProxyAdmin 0x07a0…32E3

    Admin of HermezAuctionProtocol and Hermez, owned by the timelock.

    WithdrawalDelayer 0x3923…6124
    Timelock 0xf7b2…4Ec3

    Enforces a 7 day delay on upgrades.

    The current deployment carries some associated risks:

    • Funds can be stolen if a contract receives a malicious code upgrade. There is a 7 days delay on code upgrades.

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