Module Name: DAI Module
Type/Category: Proxy —> Dai.sol and DaiJoin.sol
The origin of DAI was designed to represent any token that the core system considers equal in value to its internal debt unit. Thus, the DAI Module contains the DAI token contract and all of the adapters DaiJoin adapters.
Key Functionalities (as defined in the smart contract)
Mint - Mint to an address
Burn - Burn at an address
Push - Transfer
Pull - Transfer From
Move - Transfer From
Approve - Allow pulls and moves
Permit - Approve by signature
name - Dai Stablecoin
symbol - DAI
version - 1
decimals - 18
totalSupply - Total DAI Supply
balanceOf(usr: address) - User balance
allowance(src: address, dst: address) - Approvals
nonces(usr: address) - Permit nonce
vat - storage of the Vat’s address
ilk - id of the Ilk for which a
GemJoin is created for
gem - the address of the
ilk for transferring
dai - the address of the
one - a 10^27 uint used for math in
DaiJoin Documentation (referenced in Join - Detailed Documentation)
Dai contract is the user facing ERC20 contract maintaining the accounting for external Dai balances. Most functions are standard for a token with changing supply, but it also notably features the ability to issue approvals for transfers based on signed messages.
Join consists of three smart contracts, one of which is the DaiJoin contract. Each join contract is created specifically to allow the given token type to be joined to the vat. Because of this, each join contract has slightly different logic to account for the different types of tokens within the system. The DaiJoin contract allows users to withdraw their Dai from the system into a standard ERC20 token.
DAI is also susceptible to the known ERC20 race condition, but should not normally be an issue with unlimited approval. We recommend any users using the
approval for a specific amount be aware of this particular issue and use caution when authorizing other contracts to perform transfers on their behalf.
There are limited sources of user error in the
join contracts system due to the limited functionality of the system. Barring a contract bug, should a user call join by accident they could always get their tokens back through the corresponding exit call on the given join contract. The main issue to be aware of here would be a well-executed phishing attack. As the system evolves and potentially more join contracts are created, or more user interfaces are made, there is the potential for a user to have their funds stolen by a malicious join contract which does not actually send tokens to the vat, but instead to some other contract or wallet.
There could potentially be a
vat upgrade that would require new
join contracts to be created.
gem contract were to go through a token upgrade or have the tokens frozen while a user's collateral was in the system, there could potentially be a scenario in which the users were unable to redeem their collateral after the freeze or upgrade was finished. This seems to be a small risk though because it would seem likely that the token going through this upgrade would want to work alongside the maker community to be sure this was not an issue.