WithPermit

Deployed on mainnet at https://etherscan.io/address/0x84b65d1c28c81ccf341f357eb669133dc5d74831#code

ds-dach

Deployed on mainnet at https://etherscan.io/address/0x64043a98f097fD6ef0D3ad41588a6B0424723b3a#code

The Dai Automated Clearing House can perform the following actions:

• Clearing of Dai and Chai cheques
• Clearing of Dai -> Eth or Chai -> Eth uniswap sales
• Clearing of Chai joins or exits

For example, A Cheque is a signed message containing the following information:

• sender : address, the author of the cheque
• receiver : address, the receiver of the funds
• amount : uint256, a token amount to transfer to the receiver from the sender
• expiry : uint256, a time after which the cheque can no longer be cleared
• fee : uint256 a token amount to be transfered from the sender to whoever submits the cheque to the clearing house
• nonce: uint256, for replay protection
• relayer : address, the address authorized to clear the transaction

Anyone who obtains such a signed message can clear them, paying the gas cost of the transaction in exchange for the fee.

Signature generation

The contract uses the typed signature format of EIP-712 to provide a nice user interface and separate similar looking Cheques that might be used by other clearing houses.

If you want to try it out, here's a guide that utilizes the api at https://api.stablecoin.services to clear a dai transfer. This requires that you have seth and ethsign installed, and a local wallet with some dai or chai available. To install seth and ethsign, see dapp.tools.

Generating the signed message:

First, generate a dai cheque using the script provided at bin/daiCheque. For example, to generate a cheque of 0.1 Dai to the ethereum foundation multisig at 0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae, paying 0.2 dai in tx fees.

First, set the environment ETH_FROM to whatever account you would like to sign the cheque with:

export ETH_FROM=0xacab #your acc

then generate the cheque and store it in a file we'll call cheque.json:

./bin/daiCheque 0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae $(seth --to-wei 0.1 'ether') $(seth --to-wei 0.2 'ether') > cheque.json

Before clearing the cheque, you need to authorize the dach contract:

seth send 0x6b175474e89094c44da98b954eedeac495271d0f "approve(address,uint256)" 0x64043a98f097fD6ef0D3ad41588a6B0424723b3a $(seth --to-int256 -1)

we can then submit the cheque to be cleared using the stablecoin.services api:

curl -X POST https://api.stablecoin.services/v1/daiCheque -d @cheque.json -H "Content-Type: application/json"