zkSync Lite logozkSync Lite

  • Total value locked$82.05 M0.97%
  • Breakdown
  • Daily TPS0.912.24%
  • 30D tx count2.32 M
  • TechnologyZK Rollup
  • PurposePayments, Tokens

    • ...

    Tokens:

    Milestones

    Rebranding

    2023 Feb 16th

    zkSync becomes zkSync Lite.

    Learn more

    zkSync 1.0 launch

    2020 Jun 18th

    zkSync is live, bringing scalable payments to Ethereum using zkRollup technology.

    Learn more
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    Description

    zkSync Lite (formerly zkSync) is a user-centric zk rollup platform from Matter Labs. It is a scaling solution for Ethereum, already live on Ethereum mainnet. It supports payments, token swaps and NFT minting.

    If you find something wrong on this page you can submit an issue or edit the information.

    Risk Analysis

    Sequencer failureState validationData availabilityUpgradeabilityProposer failure

    State validation

    ZK proofs (SN)

    ZK-SNARKS 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.

    Upgradeability

    21d or no delay

    There is 21d for upgrades initiated by ZkSync Multisig. The 9 of 15 Security Council can override the delay and allow instant upgrade. Some system components can be changed with no delay but that do not impede the ability for users to withdraw permissionlessly.

    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 14d, users can use the exit hatch to withdraw their funds.

    Proposer failure

    Use escape hatch

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

    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. Once the proof is processed on the Ethereum blockchain the L2 block is instantly finalized.

    1. Validity proofs - zkSync FAQ
    2. ZkSync.sol#L549 - Etherscan source code, proveBlocks function

    Zero knowledge SNARK cryptography is used

    Despite their production use ZK-SNARKs 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 ZK-SNARKs require a trusted setup to operate.

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

    1. Cryptography used - zkSync FAQ
    2. PlonkCore.sol#L1193 - Etherscan source code

    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. Overview - zkSync documentation
    2. ZkSync.sol#L44 - Etherscan source code, commitBlockInfo struct

    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. How decentralized is zkSync - zkSync FAQ
    2. ZkSync.sol#L422 - Etherscan source code, requireActiveValidator in commitBlock function

    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. They can still exit the system.

    1. Priority queue - zkSync FAQ
    2. ZkSync.sol#L977 - Etherscan source code, addPriorityRequest function
    3. ZkSync.sol#L600 - Etherscan source code, activateExodusMode function

    Withdrawals

    Regular exit

    The user initiates the withdrawal by submitting a transaction on L2. 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.

    1. Withdrawing funds - zkSync 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 if the request is serviced the operation follows the flow of a regular exit.

    1. Withdrawing funds - zkSync documentation
    2. ZkSync.sol#L325 - Etherscan source code, requestFullExit function
    3. ZkSync.sol#L360 - Etherscan source code, requestFullExitNFT function

    Emergency exit

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

    • Funds can be lost if the user is unable to generate the non-trivial zk proof for exodus withdraw.

    1. Withdrawing funds - zkSync documentation
    2. README.md - zkSync Exit Tool
    3. ZkSync.sol#L622 - Etherscan source code, performExodus function

    Permissions

    The system uses the following set of permissioned addresses:

    ZkSync Multisig 0xE24f…0d99

    This Multisig is the owner of Upgrade Gatekeeper contract and therefore is allowed to perform upgrades for Governance, Verifier and ZkSync contracts. It can also change the list of active validators and appoint the security council (by upgrading the ZkSync contract). This is a Gnosis Safe with 4 / 7 threshold.

    ZkSync Multisig participants 0x1567…68BF0xd7aF…F36F0x8429…152f0x702c…78b70x9dF8…747A0x3068…d2Bc0xa265…6769

    Those are the participants of the ZkSync Multisig.

    Security Council 0xa260…17690x9D5d…f6070x002A…73460x71E8…88c30x76C6…cB110xFBfF…31900xAfC2…c0d60x4d1E…38C60x19eD…85670x3941…e1b60x399a…52C20xee8A…5eaB0xe7CC…231f0xA093…e33B0x225d…086e

    The Security Council's only role is to reduce the upgrade delay to zero if 9 of its members decide to do so. The council has 15 members which are hardcoded into the ZkSync contract. Changing the council requires a ZkSync contract upgrade.

    1. Security Council Members - Etherscan source code
    2. Security Council 2.0 - Matter Labs blog post
    Active validators 0x01c3…F91e

    Those actors are allowed to propose, revert and execute L2 blocks on L1.

    Token listing beneficiary 0x2A0a…d027

    Account receiving fees for listing tokens. Can be updated by ZkSync Multisig.

    Smart Contracts

    A diagram of the smart contract architecture
    A diagram of the smart contract architecture

    The system consists of the following smart contracts:

    ZkSync 0xaBEA…fBEFImplementation (Upgradable)Additional implementation (Upgradable)Admin

    The main Rollup contract. Allows the operator to commit blocks, provide zkProofs (validated by the Verifier) and processes withdrawals by executing blocks. Users can deposit ETH and ERC20 tokens. This contract also defines the upgrade process for all the other contracts by enforcing an upgrade delay and employing the Security Council which can shorten upgrade times. This contract can store any token.

    Can be upgraded by: ZkSync Multisig

    Upgrade delay: 21d or 0 if overridden by 9 of 15 Security Council

    Verifier 0x5290…d06DImplementation (Upgradable)Admin

    Implements zkProof verification logic.

    Can be upgraded by: ZkSync Multisig

    Upgrade delay: 21d or 0 if overridden by 9 of 15 Security Council

    Governance 0x3446…aF01Implementation (Upgradable)Admin

    Keeps a list of block producers, NFT factories and whitelisted tokens.

    Can be upgraded by: ZkSync Multisig

    Upgrade delay: 21d or 0 if overridden by 9 of 15 Security Council

    UpgradeGatekeeper 0x38A4…C939

    This is the contract that owns Governance, Verifier and ZkSync and facilitates their upgrades. The upgrade constraints are defined by the ZkSync contract.

    TokenGovernance 0x35cc…4e86

    Allows anyone to add new ERC20 tokens to zkSync Lite given sufficient payment.

    Can be upgraded by: ZkSync Multisig

    Upgrade delay: No delay

    1. Governance.sol#L93 - Etherscan source code
    NftFactory 0x7C77…552D

    Allows for withdrawing NFTs minted on L2 to L1.

    Can be upgraded by: ZkSync Multisig

    Upgrade delay: No delay

    1. Governance.sol#L205 - Etherscan source code

    TVL is calculated based on these smart contracts and tokens:

    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).