ERC-2021: Payoutable Token

Simple Summary

An extension to the ERC-20 standard token that allows Token wallet owners to request payout from their wallet, by calling the smart contract and attaching a payout instruction string.

Actors

Token Wallet Owners

The person or company who owns the wallet, and will order payout.

Token contract owner / agent

The entity, company responsible/owner of the token contract, and token issuing/minting. This actor is in charge of trying to fulfill all payout request(s), reading the payout instruction(s), and correlate the payout details.

Orderer

An actor who is enabled to initiate payout orders on behalf of a token wallet owner.

Abstract

Token wallet owners (or approved addresses) can order payout requests through blockchain. This is done by calling the orderPayoutFrom or orderPayoutFrom methods, which initiate the workflow for the token contract operator to either honor or reject the payout request. In this case, payout instructions are provided when submitting the request, which are used by the operator to determine the destination of the funds.

In general, it is not advisable to place explicit routing instructions for the payouts on a verbatim basis on the blockchain, and it is advised to use a private communication alternatives, such as private channels, encrypted storage or similar, to do so (external to the blockchain ledger). Another (less desirable) possibility is to place these instructions on the instructions field in encrypted form.

Motivation

Nowadays most of the token payout requests, need a previous centralized transaction, to be able to define the payout destination to be able to execute the payout (burn transaction). In the aim of trying to bring all the needed steps into decentralization, exposing all the needed steps of token lifecycle and payment transactions, a payout request can allow wallet owner to initiate the payout order via blockchain. Key benefits:

• Payout, burning traceability is enhanced bringing the initiation into the ledger. All payment, payout statuses can be stored on chain.
• Almost all money/token lifecycle is covered via a decentralized approach, complemented with private communications which is common use in the ecosystem.

In this case, the following movement of tokens are done as the process progresses:

• Upon launch of the payout request, the appropriate amount of funds are placed on a hold with a predefined notary defined by the platform, and the payout is placed into a Ordered state
• The operator then can put the payout request InProcess, which prevents the orderer of the payout from being able to cancel the payout request
• After checking the payout is actually possible the operator then executes the hold, which moves the funds to a suspense wallet and places the payout into the FundsInSuspense state
• The operator then moves the funds offchain (usually from the omnibus account) to the appropriate destination account, then burning the tokens from the suspense wallet and rendering the payout into the Executed state
• Either before or after placing the request InProcess, the operator can also reject the payout, which returns the funds to the payer and eliminates the hold. The resulting end state of the payout is Rejected
• When the payout is Ordered and before the operator places it into the InProcess state, the orderer of the payout can also cancel it, which frees up the hold and puts the payout into the final Cancelled state

Specification

interface IPayoutable /* is ERC-20 */ {
    enum PayoutStatusCode {
        Nonexistent,
        Ordered,
        InProcess,
        FundsInSuspense,
        Executed,
        Rejected,
        Cancelled
    }
    function authorizePayoutOperator(address orderer) external returns (bool);
    function revokePayoutOperator(address orderer) external returns (bool);
    function orderPayout(string calldata operationId, uint256 value, string calldata instructions) external returns (bool);
    function orderPayoutFrom(string calldata operationId, address walletToBePaidOut, uint256 value, string calldata instructions) external returns (bool);
    function cancelPayout(string calldata operationId) external returns (bool);
    function processPayout(string calldata operationId) external returns (bool);
    function putFundsInSuspenseInPayout(string calldata operationId) external returns (bool);
    function executePayout(string calldata operationId) external returns (bool);
    function rejectPayout(string calldata operationId, string calldata reason) external returns (bool);

    function isPayoutOperatorFor(address walletToDebit, address orderer) external view returns (bool);
    function retrievePayoutData(string calldata operationId) external view returns (address walletToDebit, uint256 value, string memory instructions, PayoutStatusCode status);

    event PayoutOrdered(address indexed orderer, string indexed operationId, address indexed walletToDebit, uint256 value, string instructions);
    event PayoutInProcess(address indexed orderer, string indexed operationId);
    event PayoutFundsInSuspense(address indexed orderer, string indexed operationId);
    event PayoutExecuted(address indexed orderer, string indexed operationId);
    event PayoutRejected(address indexed orderer, string indexed operationId, string reason);
    event PayoutCancelled(address indexed orderer, string indexed operationId);
    event PayoutOperatorAuthorized(address indexed walletToBePaidOut, address indexed orderer);
    event PayoutOperatorRevoked(address indexed walletToBePaidOut, address indexed orderer);
}

Functions

authorizePayoutOperator

Wallet owner, allows a given address to be payout orderer.

revokePayoutOperator

Wallet owner, Revokes a given address to be payout orderer.

orderPayout

Creates a payout request, that will be processed by the token operator. The function must revert if the operation ID has been used before.

orderPayoutFrom

Creates a payout request, on behalf of a wallet owner, that will be processed by the token operator. The function must revert if the operation ID has been used before.

cancelPayout

Cancels a payout request.

processPayout

Marks a payout request as on process. After the status is on process, order cannot be cancelled.

putFundsInSuspenseInPayout

Put a given payout in suspense. Can only be done if it is in process.

executePayout

Burn the amount of tokens and marks a payout request as executed.

rejectPayout

Rejects a given operation with a reason.

isApprovedToOrderPayout

Checks that given player is allowed to order payout requests, for a given wallet.

retrievePayoutData

Retrieves all the payout request data. Only operator, tokenHolder, and orderer can get the given operation data.

Events

Payout Ordered

Emitted when an token wallet owner orders a payout request.

PayoutFundsInSuspense

Emitted when an operator puts fund in suspense.

PayoutInProcess

Emitted when an operator accepts a payout request, and the operation is in process.

PayoutExecuted

Emitted when an operator has executed a payout request.

PayoutRejected

Emitted when an operator has rejected a payout request.

PayoutCancelled

Emitted when a token holder, orderer, has cancelled a payout request. This can only be done if the operator hasn’t put the payout order in process.

PayoutOperatorAuthorized

Emitted when a given player, operator, company or a given persona, has been approved to start payout request for a given token holder.

PayoutOperatorRevoked

Emitted when a given player has been revoked initiate payout requests.

Rationale

This standards provides a functionality to allow token holders to start payout requests in a decentralized way.

It’s important to highlight that the token operator, need to process all payout request, updating the payout status based on the linked payment that will be done.

Payout instruction format is open. ISO payment standard like is a good start point.

This EIP uses EIP-1996 to hold the money after a payout is ordered. The token contract owner or agent, whose implementation is not part of this proposal, acts as a predefined notary to decide if the payout is executed or not.

The operationId is a string and not something more gas efficient to allow easy traceability of the hold and allow human readable ids. It is up to the implementer if the string should be stored on-chain or only its hash, as it is enough to identify a hold.

The operationId is a competitive resource. It is recommended, but not required, that the hold issuers used a unique prefix to avoid collisions.

Backwards Compatibility

This EIP is fully backwards compatible as its implementation extends the functionality of ERC-20 and [ERC-1996].

Implementation

The GitHub repository IoBuilders/payoutable-token contains the reference implementation.

Contributors

This proposal has been collaboratively implemented by adhara.io and io.builders.

Copyright

Copyright and related rights waived via CC0.

Citation

Please cite this document as:

Fernando Paris <fer@io.builders>, Julio Faura <julio@adhara.io>, Daniel Lehrner <daniel@io.builders>, "ERC-2021: Payoutable Token [DRAFT]," Ethereum Improvement Proposals, no. 2021, May 2019. [Online serial]. Available: https://eips.ethereum.org/EIPS/eip-2021.