dapp-whisperer / ibbtc

Interest-Bearing Bitcoin

Interest-bearing Badger BTC (ibBTC)

• bBTC.sol is the interest-bearing bitcoin ERC20 token.

• A peak refers to any third party integration in the protocol. The system is designed to support many such peaks which can be added or removed later and allow for custom logic specific to the peak. BadgerSettPeak.sol let's to mint/redeem bBTC with/in Badger Sett LP tokens. There is a configurable mint and redeem fee, charged in bBTC.

• Core.sol is responsible for actually minting/burning the bBTC tokens. core.totalSystemAssets() provides the summation of all LP tokens held in all peaks, denominated in bitcoin. For e.g. a Sett LP token held in BadgerSettPeak is priced as:

function _settToBtc(CurvePool memory pool, uint amount) internal view returns(uint) {
    return amount
        .mul(pool.sett.getPricePerFullShare())
        .mul(pool.swap.get_virtual_price())
        .div(1e36);
}

This has the affect that as various strategies are employed on the sett, and the underlying curve pool LP token accrues interest (from trading fee), it is reflected in totalSystemAssets(). Then it becomes straight-forward to price a bBTC like so:

function getPricePerFullShare() override public view returns (uint) {
    uint _totalSupply = IERC20(address(bBTC)).totalSupply();
    if (_totalSupply > 0) {
        return totalSystemAssets().mul(1e18).div(_totalSupply);
    }
    return 1e18;
}

getPricePerFullShare() is used to determine the bBTC:bSett exchange rate.

Compile

npm run compile

Tests

Needs Alchemy API key. export ALCHEMY=<API_KEY>

npm t

• Run against deployed contracts

npm run test:dryrun

Deployments

• Local

npx hardhat node
npx hardhat run scripts/deploy.js --network local

Addresses will be written to deployments/local.json.

• Mainnet

export PRIVATE_KEY=
export INFURA_PROJECT_ID=

npx hardhat run scripts/deployMainnet.js --network mainnet

Addresses will be written to deployments/mainnet.json.

Coverage

npm run coverage