ZKSwap 1.0Description
ZKSwap is a fork of ZkSync with added AMM functionality. Based on ZK-Rollup technology, ZKSwap aims to execute the full functionality of Uniswap on Layer 2, while ensuring the core value of decentralized exchange. ZKSwap aims to increase the TPS by multiple orders of magnitude compared to Uniswap, and make transaction processing hardly consume any gas fees.
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Risk analysis
State validation
ZK proofs (SN)ZK-SNARKS are zero knowledge proofs that ensure state correctness, but require trusted setup.
Data availability
On chainAll of the data needed for proof construction is published on chain.
Upgradeability
8 days delayThe code that secures the system can be changed arbitrarily but users have some time to react.
Sequencer failure
Force exit to L1The user is only able to submit an L1 withdrawal request and force the sequencer to include it on L2. After that the user exits the system with their funds.
Validator failure
Escape hatch (ZK)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.
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.
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.
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.
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.
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.
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.
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.
Permissioned Addresses
The system uses the following set of permissioned addresses:
This address is the master of Upgrade Gatekeeper contract, which is allowed to perform upgrades for Governance, Verifier, VerifierExit, PairManager and ZkSync contracts.
This actor is allowed to propose, revert and execute L2 blocks on L1. A list of active validators is kept inside Governance contract and can be updated by zkSwap 1.0 Admin.
Smart Contracts
The system consists of the following smart contracts:
The main Rollup contract. Operator commits blocks, provides zkProof which is validated by the Verifier contract and process withdrawals (executes blocks). Users deposit ETH and ERC20 tokens. This contract defines the upgrade delay in the UPGRADE_NOTICE_PERIOD constant that is currently set to 8 days. This contract can store any token
Additional contract to store implementation details of the main ZkSync contract.
The source code of this contract is not verified on Etherscan.
Keeps a list of block producers and whitelisted tokens.
This is the contract that implements the upgrade mechanism for Governance, Verifier and ZkSync. It relies on the ZkSync contract to enforce upgrade delays.
The current deployment carries some associated risks:
Funds can be stolen if a contract receives a malicious code upgrade. There is a 8 days delay on code upgrades.
the source code of unverified contracts contains malicious code (CRITICAL).