Module Name: Collateral Module
Type/Category: DSS —> Join.sol & Flip.sol
The collateral module is deployed for every new
ilk (collateral type) added to
Vat. It contains all the adapters and auction contracts for one specific collateral type.
For other information related to the collateral module, read the following resources:
The Collateral Module has 2 core components consisting of the
Join - adapters that are used to deposit/withdraw unlocked collateral into the
Vat. Join contains three smart contracts:
Each of the
join contracts are specifically used for the given token type to be
join'ed to the
vat. Due to this fact, each
join contract has slightly different logic to account for the different types of tokens within the system.
Flipper - collateral Auctions are used to sell collateral from Vaults that have become undercollateralized in order to preserve the collateralization of the system. The
Cat sends bitten collateral to the Flip module to be auctioned off to Keepers. The collateral auction has two phases:
dent. See the Gotchas section of the Flipper's documentation for more on the
dent auction phases.
Join - the purpose of join adapters is to retain the security of the system, allowing only trusted smart contracts to add/remove value to/from the
Vat. The location of collateral deposited/locked in Vaults is in the respective Join adapter.
Flipper - the purpose of collateral auctions is to decrease the market risk of collateral that is backing Dai. The main priorities of the Flipper are:
To cover the amount of total debt (minted Dai + accrued fees) of the Vault.
To return as much collateral back to the Vault owner as possible.
When a user desires to enter the system and interact with the
dss contracts, they must use one of the
If there was a contract bug in a
join contract and a user was to call
join by accident, they can still retrieve their tokens back through the corresponding
exit call on the given
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.
Potential Phishing Attacks
As the MCD system evolves, we will see many more
join contracts, user interfaces, etc. This surfaces the potential for a user to have their funds stolen by a malicious
join contract which would send tokens to an external contract or wallet, instead of the