USDS Token and contracts associated

This repository includes 3 smart contracts:

• USDS token
• UsdsJoin
• DaiUsds Converter

USDS token

This is a standard erc20 implementation with regular permit functionality + EIP-1271 smart contract signature validation.

The token uses the ERC-1822 UUPS pattern for upgradeability and the ERC-1967 proxy storage slots standard. It is important that the UsdsDeploy library sequence be used for deploying the token.

OZ upgradeability validations

The OZ validations can be run alongside the existing tests:
VALIDATE=true forge test --ffi --build-info --extra-output storageLayout

UsdsJoin

This is the contract in charge of minting the erc20 IOUs in exchange of native vat.dai balance. It also manages the reverse operation, burning tokens and releasing vat.dai. A noticeable code difference against DaiJoin is this contract doesn't have any permissions system at all. However, in practice, UsdsJoin acts the exact same way as the production DaiJoin implementation. This is because there isn't any wards(address) set there.

DaiUsds

It is a permissionless converter between Dai and Usds (both ways). Using the public functions of UsdsJoin and DaiJoin moves from one token to the other. The exchange rate is 1:1. It is just a "convenience" contract, users could still get the same outcome executing the separate methods in the joins or use any other converter implementation.