Custodian core

CustodianCore

CustodianCore is the governance contract of custodian alliance on Conflux chain. It maintains the information of custodian members and configurations for custodian nodes, including: * Custodian member's address/public key of different chain * The address of all cTokens and their configurations such as mint/burn fee * The information of token sponsors * The upper/lower bounds of custodian alliance's bitcoin hot wallet

Ownership and authorities

At this point, the owner of CustodianCore is Conflux admin, who is enabled to modify custodian node configurations and custodian membership.
CustodianCore is the owner of all cToken so only it has the authority to mint cTokens.

Contract ABI

CustodianCore ABI

Core Storage Variables

ITokenBase[] public token_list;

Registered cTokens.

mapping(address => string) public token_reference;

Mapping of cToken address to external chain assets(reference), reference can be 'eth'/'btc'/lowercase erc20 address.

For example,

cETH address => 'eth',

cBTC address => 'btc',

cUSDT address => '0xdac17f958d2ee523a2206206994597c13d831ec7'.

mapping(address => uint8) public token_decimals;

Mapping of cToken address to external chain decimals.

For example,

cETH address => 18,

cBTC address => 8,

cUSDT address => 6.

mapping(string => bool) public admin_token;

Denote each cToken is admin token or not.

Admin token can only be sponsored by whitelist admin of custodian core contract, and will maintain both hot and cold wallet. For non-admin token, anyone can be its sponsor and only hot wallet will be maintained.

mapping(string => address) reference_token; // inverse token_reference

Anti mapping of token_reference.

mapping(string => uint256) public burn_fee;

The fee taken from user during cToken burn. Note the decimals is decimals of the reference token.

For example, the sponsor want to take 0.1 cUSDT when user burn cUSDT, here burn_fee['usdt'] should be 0.1 * 1e6.

mapping(string => uint256) public mint_fee;

The fee taken from user during cToken mint. Note the decimals is decimals of the reference token.

mapping(string => uint256) public wallet_fee;

When a user want to migrate token from ethereum to conflux, his/her receive wallet will be deployed firstly if it is not deployed before. wallet_fee denote the fee taken from user during deployment of receive wallet. Note the decimals is decimals of the reference token.

mapping(string => uint256) public minimal_mint_value;

The remaining value of reference token in user's receive wallet must be larger than minimal mint value, otherwise the custodian alliance will not mint for it.

Note: for btc, use btc_minimal_mint_value.

uint256 public btc_minimal_mint_value

cBTC minimal mint value.

mapping(string => uint256) public minimal_burn_value;

The minimal burn value of corresponding cToken, the burn will fail if burn value is not enough.

Note: for btc, use btc_minimal_burn_value.

uint256 public btc_minimal_burn_value;

cBTC minimal burn value.

mapping(string => uint256) public minimal_burn_value;

The minimal burn value of corresponding cToken, the burn will fail if burn value is not enough.

mapping(string => uint256) public token_cooldown; // second

This can only set by custodian core whitelist admin. The token spnosor should not change the token parameters frequently, so the sponsor must wait a cooldown after the token parameters is changed.

Core Functions:

function sponsorToken(
        string memory ref, // lowercase erc20 ethereum address
        uint256 amount, // amount of cETH mortgaged
        uint256 _burn_fee, // burn fee of erc20 token, in erc20 decimals
        uint256 _mint_fee, // mint fee of erc20 token, in erc20 decimals
        uint256 _wallet_fee, // receive wallet fee of erc20 token, in erc20 decimals
        uint256 _minimal_mint_value, // minimal mint value of erc20 token, in erc20 decimals
        uint256 _minimal_burn_value // minimal burn value of erc20 token, in erc20 decimals
) public;

This function can be called by anyone.

This function helps msg.sender become the sponsor of an erc20 token, specified by ref.

The governance contract will transfer amount cETH from msg.sender by operator authority, and compare the amount to the current sponsor of ref(if exists), the sponsor will be replaced by msg.sender if amount is large enough. The token parameters of ref will also be replaced by the parameters sender provided, if the token is not in cooldown.

For more information of sponsor replacement logic, see token sponsor.

function setTokenParams(
        string memory ref, // lowercase erc20 ethereum address
        uint256 _burn_fee,
        uint256 _mint_fee,
        uint256 _wallet_fee,
        uint256 _minimal_mint_value,
        uint256 _minimal_burn_value
) public;

This function can be called by anyone.

This function helps the sponsor of token ref to change the token parameters if the token is not in cooldown.