diff --git a/packages/protocol/docs/iprover.md b/packages/protocol/docs/iprover.md new file mode 100644 index 0000000000..8168dba337 --- /dev/null +++ b/packages/protocol/docs/iprover.md @@ -0,0 +1,60 @@ +# Implementing arbitrary token payments with IProver interface + +In this guide, we will outline the steps to implement a solution that enables prover pools to accept arbitrary ERC-20 tokens as payments for providing with proofs. This solution allows proposers to interact with pools (implementing `IProver`), agree on a price for proving a block, and make payments using ERC-20 tokens. + +NOTE: This works also with NFTs (ERC-721/ERC-1155) as well (applying the proper `approval`/`approvalForAll`), just because it might be less likely those will be used as payment methods, we highlighted the ERC-20. + +## Prerequisites + +Before implementing this solution, make sure you have an existing ERC-20 token contract that you want to accept as payment in your ProverPool. + +## Implementation Steps + +### Step 1: An example ProverPool Contract + +Start by creating a ProverPool contract that implements the `IProver` interface. This interface should include the `onBlockAssigned` function, which will be called during `proposeBlock()`. +A boilerplate (non-comprehensive) example: + +```solidity +// Import necessary libraries and interfaces +import "./IProver.sol"; + +// Define the ProverPool contract +contract ProverPool is IProver { + + // ERC-20 address of the payment token + address ERC20TokenAddress; + + // Implement the onBlockAssigned function + function onBlockAssigned( + uint64 blockId, + TaikoData.BlockMetadataInput calldata input, + TaikoData.ProverAssignment calldata assignment + ) external { + // Decode the assignment data to retrieve signatures and other information + (bytes memory proverSignature, uint256 tokenAmount) = decodeAssignmentData(assignment); + + // 1. Verify the prover signature is valid (off-chain verification) + require(isValidSignature(proverSignature, input), "Invalid prover signature"); + + // 2. Execute the transfer transaction + ERC20(ERC20TokenAddress).transferFrom(tx.origin, address(this), tokenAmount); + + // Additional logic goes here + } + + // Implement functions to decode assignment data, verify signature, etc. +} +``` + +### Step 2: Proposer-prover off-chain interaction + +The proposer and prover interact off-chain to agree on the price and perform the ERC-20 token approval. Here's an example of how this interaction might work: + +1. Proposer asks the ProverPool for the cost of proving a block and receives a price (e.g., `10 DAI` tokens). If price is acceptable, prover provides proposer with a valid ECDSA signature which signs the commitment (e.g.: transaction list hash), expiration and price. + +2. Proposer executes the following transaction: `ERC-20(DAI_ADDRESS).approve(proverPool, 10)` (or if he/she thinks this pool will be a long-term solution the approval amount can be bigger). + +3. Proposer creates the `ProverAssignment` struct data (obviously together with the `input` and `txList`) and submits the `proposeBlock()` with the necessary parameters. + +During `proposeBlock()` transaction, the `onBlockAssigned()` hook which will evaluate the validity of the prover signature, and if that one is correct then executest he transfer of `10 DAI`.