zkLink is a unified multi-chain trading infrastructure secured with zk-SNARKS, empowering the next-generation of decentralized trading products such as order book DEX, NFT marketplaces, and more.

zkLink builds a ZK-Rollup middleware that natively connects to various L1s and L2s, and provides an array of high-level APIs. Developers can easily deploy trading dApps with high customizability and access to aggregated liquidity, while their end users can benefit from a seamless multi-chain trading experience. Moreover, zkLink also supports OFT (Omnichain Fungible Token) issuing and bridging.

Benefits of using zkLink infra

Asset Aggregation

• Multi-chain Token Listing and Trading: list and trade tokens across various L1s and L2s, including FTs and NFTs, without a bridge to mitigate cross-chain risks and fees.

• Multi-chain Token Portfolio Management: a single wallet to manage multi-chain portfolios, just as in a centralized exchange.

Liquidity Aggregation

• Token Merge: tokens issued on different blockchains by the same entity (e.g., USDT ERC20, USDT SPL, USDT BEP20) will be merged into a single token (USDT) within the zkLink rollup network.

• Stablecoin Liquidity Unification: USD, a unified pricing currency, is introduced within the zkLink system, which eliminates disparities among fiat-backed stablecoins from different chains. The auto-conversion from selected stablecoins (USDC, USDP, BUSD, etc.) to USD is optional for dApps.

App-specific Zero-knowledge Circuit

• High customizability: developers can choose which networks to connect, which to put DA on, and tailor specific functions.

• High performance: 1000+ TPS to bridge the gap between high-frequency traders' needs and on-chain products.

• High efficiency: the app-specific circuit is considerably smaller than general-purpose zk circuits, resulting in lower computational resource and on-chain gas consumption.

Types of Networks that zkLink Supports

EVM-compatible ZK-Rollup VMs

zkSync, Scroll, Linea, Polygon ZKVM, Taiko, etc.

EVM-incompatible ZK-Rollup VMs

Starknet, etc.

EVM-compatible Optimistic-Rollups

Arbitrum, Optimism, etc.

Wallet Integration & AA Wallet

💡Account abstraction unifies contract accounts and EOAs. Integrating AA wallets brings better user experience to dApps built on top of zkLink. Smart contract wallets are much more flexible than EOAs, allowing users to control their accounts by smart contract rather than simply a private key, and to define their account logic such as permission controls, transaction limits, wallet recovery, etc.

Taking UniPass as an example, UniPass offers a user-friendly experience for managing smart contract wallets using email and password. We believe this is crucial for users who are not yet familiar with crypto.

Required Conditions

• supports EIP712 signing

• supports generation of zkLink_key

  1. 1.

     zkLink_key must be generated and kept secret by user clients;

  2. 2.

     zkLink_key is the private key to generation EdDSA signature, and every single Layer2 transaction needs to be signed by zkLink_key;

  3. 3.

     In the example of Unipass integration, a zkLink_key is generated when the user signs from the browser client with the client slice of MPC master key (user key). This zkLink_key will not be exported to Unipass server.

Optional Condition

• compatible with proxy deposit contract

  1. 1.

     we suggest AA wallets to support zkLink proxy deposit to improve UX in many cases;

  2. 2.

     AA wallets that adopt the zkLink auto transfer function can directly call transfer to AA wallet.

AA wallet flow

AA Wallet Security

AA wallets integrating to zkLink must meet Dunkirk Test requirements, i.e., assets security is not dependent to agency, and users can still retrieve assets even when the wallet service provider goes down.

In the case study of Unipass, users can download an open-source front-end or use a web form with IPFS hosting to recover their account and migrate to EOAs if the Unipass server fails.

Simple Integration (Multi-Chain Spot Exchange)

The graphic below illustrates an example integration of zkLink infrastructure with ZKEX2.0, and demonstrates how to quickly deploy a decentralized multi-chain spot exchange based on the CLOB model (Central Limit Order Book).

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Integration Features

• Autonomous maintenance of user asset information, designing for high-performing order matching

• Easy deployment and transaction settlement with plug-and-play APIs; direct connection to the sequencer system operated by zkLink team

• Easy gas fee handling across different public chains

Functions of ZKEX 2.0 Integration

• Multi-chain orderbook spot trading

• Multi-chain spot asset conversion

Lightweight Integration

💡 A case study of zkJump.io to showcase lightweight integration

zkJump Server

zkJump Server monitors related on-chain events, offers broker services for cross-chain transfers, and provides backend service for zkJump.io.

In practice, the zkJump Server does not need to maintain a complete set of user nonce or account balance information as ZKEX.com does. User balance can be directly fetched from zkLink L2 infra, reducing the development and operational costs of zkJump considerably.

The fee for Proxy Withdraw Operation is covered by zkJump operators.

zkJump Bridge Contract

The contract is developed and maintained by zkJump, with the following functions:

• Collect cross-chain transfer fees

• Integrate to on-chain DEXs. For example, tokens swapped in Uniswap could be directly transferred to the destined chain via zkJump integrated on Uniswap

Tokenomics

ZKL, the utility token and governance token of zkLink protocol, is a standard ERC20 token, and its smart contract code is derived from the ERC20 contract provided by OpenZeppelin.

The total amount of ZKL will be kept at 1 billion and non-inflationary. There will be no individual or entity that can issue new units of ZKL.

ZKL as zkLink block fee

ZKL token is the de facto payment token for the dApps to access the zkLink service and pay for the usage of the network block space.

When the dApp server commits a block to the zkLink contract, it has to pay for the validator service in ZKL:

block_fee = total_block_unit * unit_price

wherein:

1. 1.

   unit_price is equal to the lowest bid among the validators;

2. 2.

   total_block_unit is the sum of units of transactions in one block;

3. 3.

   unit is the computing cost of each operation.

ZKL as governance token

1. 1.

   dApps have to stake ZKL to gain access to manager contract;

2. 2.

   validators have to stake ZKL as a guarantee deposit, and help generate zero-knowledge proofs to receive ZKL as rewards;

3. 3.

   Users of the zkLink Eco dApps will be motivated to purchase and hold ZKL to unlock perks and special user rights such as trading fee discounts;

4. 4.

   ZKL holders can stake ZKL to obtain veZKL to initiate proposals, and vote on the proposals to govern the development of the protocol.

ZKLINK OFFICIAL LINKS

🌐 Official website: https://zk.link/

Medium:https://zklinkdefi.medium.com/

📄 Document：https://docs.zk.link/docs/Introduction

Telegram:https://t.me/zkLinkorg

Twitter:https://twitter.com/zkLink_Official

Github:https://github.com/zkLinkProtocol

Official Zealy Page: https://zealy.io/c/zklink/questboard

🌐 Official Galxe Page: https://galxe.com/zkLink/campaigns