EIPs/EIPS/eip-725.md

eip	title	author	discussions-to	status	type	category	requires	created
725	General key-value store and execution standard	Fabian Vogelsteller (@frozeman), Tyler Yasaka (@tyleryasaka)	https://github.com/ethereum/EIPs/issues/725	Draft	Standards Track	ERC	165, 173	2017-10-02

Simple Summary

A standard interface for a smart contract based account with attachable key value store.

Abstract

The following describes standard functions for a unique smart contract based account that can be used by humans, groups, organisations, objects and machines.

The standard is divided into two sub standards:

ERC725X: Can execute arbitrary smart contracts and deploy other smart contracts.

ERC725Y: Can hold arbitrary data through a generic key/value store.

Motivation

Standardizing a minimal interface for a smart contract based account allows any interface to operate through these account types. Smart contact based accounts following this standard have the following advantages:

• can hold any asset (native token, e.g. ERC20 like tokens)
• can execute any smart contract and deploy smart contracts
• have upgradeable security (through owner change, e.g. to a gnosis safe)
• are basic enough to work for for a long time
• are extensible though additional standardisation of the key/value data.
• can function as an owner/controller or proxy of other smart contracts

Specification

ERC725X

ERC165 identifier: 0x44c028fe

execute

Executes a call on any other smart contracts, transfers the blockchains native token, or deploys a new smart contract. MUST only be called by the current owner of the contract.

function execute(uint256 operationType, address to, uint256 value, bytes data) public

The operationType can execute the following operations:

• 0 for call
• 1 for delegatecall
• 2 for create2
• 3 for create

Others may be added in the future.

Triggers Event: ContractCreated, Executed

Events

Executed

MUST be triggered when execute creates a new call using any operationType.

event Executed(uint256 indexed _operation, address indexed _to, uint256 indexed _value, bytes _data);

ContractCreated

MUST be triggered when execute creates a new contract using the operationType 2, 3.

event ContractCreated(address indexed contractAddress)

ERC725Y

ERC165 identifier: 0x5a988c0f

getData

Returns array of data at multiple keys.

function getData(bytes32[] calldata _keys) public view returns(bytes[] memory)

setData

Sets array of data at multiple keys. MUST only be called by the current owner of the contract.

Triggers Event: DataChanged

function setData(bytes32[] calldata _keys, bytes[] calldata _values) public 

Events

DataChanged

MUST be triggered when setData was successfully called.

event DataChanged(bytes32 indexed key, bytes value)

Ownership

This contract is controlled by an owner. The owner can be a smart contract or an external account. This standard requires ERC173 and should implement the functions:

• owner() view
• transferOwnership(address newOwner)

The event:

• OwnershipTransferred(address indexed previousOwner, address indexed newOwner)

Data keys

Data keys, should be the keccak256 hash of a type name. e.g. keccak256('ERCXXXMyNewKeyType') is 0x6935a24ea384927f250ee0b954ed498cd9203fc5d2bf95c735e52e6ca675e047

The ERC725JSONSchema standard defines how keys should be named and generated. This JSON schema can be used to auto decode ERC725Y values from smart contracts for application and smart contract interactions.

Default key values

ERC725 key standards need to be defined within new standards, we suggest the following defaults:

Name	Description	Key	value
SupportedStandards:XYZ	Allows to determine standards supported by this contract	0xeafec4d89fa9619884b6b89135626455000000000000000000000000xxxxxxxx, where xxxxxxxx is the 4 bytes identifier of the standard supported	Value can be defined by the standard, by default it should be the 4 bytes identifier e.g. 0x7a30e6fc
SupportedStandards:ERC725Account	Allows to determine standards supported by this contract	0xeafec4d89fa9619884b6b89135626455000000000000000000000000afdeb5d6, where afdeb5d6 is the 4 bytes part of the hash of keccak256('ERC725Account')	Value is the 4 bytes identifier 0xafdeb5d6

ERC725Account

An SupportedStandards > ERC725Account (See key > value above) is an ERC725 smart contract based account/profile for storing of assets and execution of other smart contracts.

• ERC173 to be controllable by an owner, that could be am external account, or smart contract
• ERC725X to interact with other smart contracts
• ERC725Y to attach data to the account for future extensibility
• COULD have ERC1271 to be able to verify signatures by the owner (or owner contracts keys).
• Should fire the event ValueReceived(address indexed sender, uint256 indexed value) if ETH is received.

A full implementation of an ERC725Account can be found found here.

Rationale

The purpose of an smart contract account is to allow an entity to exist as a first-class citizen with the ability to execute arbitrary contract calls.

Implementation

• Latest implementation

Solidity Interfaces

// SPDX-License-Identifier: CC0-1.0
pragma solidity >=0.5.0 <0.7.0;

//ERC165 identifier: `0x44c028fe`
interface IERC725X  /* is ERC165, ERC173 */ {
    event ContractCreated(address indexed contractAddress);
    event Executed(uint256 indexed operation, address indexed to, uint256 indexed  value, bytes data);

    function execute(uint256 operationType, address to, uint256 value, bytes memory data) external;
}

//ERC165 identifier: `0x5a988c0f`
interface IERC725Y /* is ERC165, ERC173 */ {
    event DataChanged(bytes32 indexed key, bytes value);

    function getData(bytes32[] calldata _keys) external view returns(bytes[] memory);
    function setData(bytes32[] calldata _keys, bytes[] calldata _values) external;
}

interface IERC725 /* is IERC725X, IERC725Y */ {

}

interface IERC725Account /* is IERC725, IERC725Y, IERC1271 */ {
    event ValueReceived(address indexed sender, uint256 indexed value);
}

Flow chart

Additional References

• Slides of the ERC Identity presentation
• In-contract claim VS claim registry
• Identity related reports
• W3C Verifiable Claims Use Cases
• Decentralised Identity Foundation
• Sovrin Foundation Self Sovereign Identity

Copyright

Copyright and related rights waived via CC0.