Crosschain KYC

Overview:

The provided smart contracts facilitate a bridge between Polygon and any other blockchain. This bridge is designed to enable KYC (Know Your Customer) verification status to be shared across chains.

Demo

Url: https://cross-chain-kyc.h4n.app/

kyc-demo.mp4

Endpoints

KYC Proxy

• Polygon (testnet):
  • adress 0xeA155E0145ff4b240b65601aC55E3d7Ed8878c4E

KYC Client

• Optimism (testnet):
  • adress 0xc3765f58a10c5636de7628ad434a08f34f2d0fdc
  • chain id: 10132
• Base (testnet):
  • adress 0xd8425b5d9d5f0a4dd1db58bed2da8070bdc931fa
  • chain id: 10160

Key Components:

KYCProxy contarct (For Polygon side) KYCClient contarct (For Base/Optimism side)

1. KYCProxy (For Polygon side):

This contract serves as the KYC registry for users. When a user's KYC verification status is received from the Base network, it is stored within this contract.

Functions:

_nonblockingLzReceive(...): - processes the incoming KYC verification data from Base.

lzReceive(...): - callable and ensures that only authorized LayerZero endpoints can submit KYC verification data.

hasValidToken(...): - allows external contracts or Dapps to check if a given address has a valid KYC token.

2. KYCClient (For Base side):

This contract facilitates the sending of KYC verification data to the Polygon network.

Functions:

setReceiverByChain(...): - allows the contract owner to set or change the recipient contract address for each chain.

sendKYCtoChain(...): - users call this function to send their KYC status from Polygon to any chain. Before doing so, the contract checks if the user has a valid KYC token on Polygon network.

How to Use:

Sharing KYC Status to Base:

Users with a valid KYC token on Polygon should interact with the KYCProxy contract. Call the sendKYCtoChain(destChainId) function, specifying the destination chain's ID (in this case, Base's ID). If the user has a valid KYC token, their address will be sent to Base network and recorded in the KYCClient contract there.

Interact with the KYCClient contract on Base (KYC DAO Interface).

pragma solidity ^0.8.0;

/**
* @title An interface for checking whether an address has a valid kycNFT token
*/
interface IKycValidity {
/// @dev Check whether a given address has a valid kycNFT token
/// @param _addr Address to check for tokens
/// @return valid Whether the address has a valid token
    function hasValidToken(address _addr) external view returns (bool valid);
}

Call the hasValidToken(address) function, passing the address you wish to check. The function will return true if the address has a valid KYC token and false otherwise.

Security

The contact code and KYCProxy addresses are not changeable. Verification of KYC client is possible only after verification on the original network. This allows to use the contract made during the hackathon in production in any projects.

KYC proof on KYC Client on any chain guarantees that the user has passed it.