ERC-2019: Fundable Token

Simple Summary

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

Actors

Token Wallet Owners

The person or company who owns the wallet, and will order a token fund request into the wallet.

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 fund request(s), reading the fund instruction(s), and correlate the private payment details.

Orderer

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

Abstract

Token wallet owners (or approved addresses) can order tokenization requests through blockchain. This is done by calling the orderFund or orderFundFrom methods, which initiate the workflow for the token contract operator to either honor or reject the fund request. In this case, fund instructions are provided when submitting the request, which are used by the operator to determine the source of the funds to be debited in order to do fund the token wallet (through minting).

In general, it is not advisable to place explicit routing instructions for debiting funds 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 issuing/funding request, based on any fiat based payment method need a previous centralized transaction, to be able to get the desired tokens issued on requester’s wallet. 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 funding request can allow wallet owner to initiate the funding request via blockchain. Key benefits:

• Funding and payment traceability is enhanced bringing the initiation into the ledger. All payment stat s 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.

Specification

interface IFundable /* is ERC-20 */ {
    enum FundStatusCode {
        Nonexistent,
        Ordered,
        InProcess,
        Executed,
        Rejected,
        Cancelled
    }
    function authorizeFundOperator(address orderer) external returns (bool);
    function revokeFundOperator(address orderer) external returns (bool) ;
    function orderFund(string calldata operationId, uint256 value, string calldata instructions) external returns (bool);
    function orderFundFrom(string calldata operationId, address walletToFund, uint256 value, string calldata instructions) external returns (bool);
    function cancelFund(string calldata operationId) external returns (bool);
    function processFund(string calldata operationId) external returns (bool);
    function executeFund(string calldata operationId) external returns (bool);
    function rejectFund(string calldata operationId, string calldata reason) external returns (bool);

    function isFundOperatorFor(address walletToFund, address orderer) external view returns (bool);
    function retrieveFundData(address orderer, string calldata operationId) external view returns (address walletToFund,       uint256 value, string memory instructions, FundStatusCode status);

    event FundOrdered(address indexed orderer, string indexed operationId, address indexed , uint256 value,         string instructions);
    event FundInProcess(address indexed orderer, string indexed operationId);
    event FundExecuted(address indexed orderer, string indexed operationId);
    event FundRejected(address indexed orderer, string indexed operationId, string reason);
    event FundCancelled(address indexed orderer, string indexed operationId);
    event FundOperatorAuthorized(address indexed walletToFund, address indexed orderer);
    event FundOperatorRevoked(address indexed walletToFund, address indexed orderer);
}

Functions

authorizeFundOperator

Wallet owner, authorizes a given address to be fund orderer.

revokeFundOperator

Wallet owner, revokes a given address to be fund orderer.

orderFund

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

orderFundFrom

Creates a fund 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.

cancelFund

Cancels a funding request.

processFund

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

executeFund

Issues the amount of tokens and marks a funding request as executed.

rejectFund

Rejects a given operation with a reason.

isFundOperatorFor

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

retrieveFundData

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

Events

FundOrdered

Emitted when an token wallet owner orders a funding request.

FundInProcess

Emitted when an operator starts a funding request after validating the instruction, and the operation is marked as in process.

FundExecuted

Emitted when an operator has executed a funding request.

FundRejected

Emitted when an operator has rejected a funding request.

FundCancelled

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

FundOperatorAuthorized

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

FundOperatorRevoked

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

Rationale

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

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

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

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.

Implementation

The GitHub repository IoBuilders/fundable-token contains the work in progress 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-2019: Fundable Token [DRAFT]," Ethereum Improvement Proposals, no. 2019, May 2019. [Online serial]. Available: https://eips.ethereum.org/EIPS/eip-2019.