ERC-6551: Non-fungible Token Bound Accounts

An interface and registry for smart contract accounts owned by non-fungible tokens.

Overview:

The system outlined in this proposal has two main components:

A singleton registry for token bound accounts
A common interface for token bound account implementations The following diagram illustrates the relationship between NFTs, NFT holders, token bound accounts, and the Registry:

Registry

The registry is a singleton contract that serves as the entry point for all token bound account address queries. It has two functions:

createAccount - creates the token bound account for an NFT given an [implementation] address
account - computes the token bound account address for an NFT given an [implementation] address

The registry is permissionless, immutable, and has no owner. The complete source code for the registry can be found in the Registry Implementation section. The registry MUST be deployed at address (0x00000000006551f9487184612e58Fe0681377558) using Nick's Factory (0x4e59b48447b37957858992ca078fbF26c0b4956c) with salt (0x0000000000000000000000000000000000000000fde8e4e1dca713016c518e31).

The registry can be deployed to any EVM-compatible chain using the following transaction:

{
  "to": "0x4e59b48447b37957858992ca078fbF26c0b4956c",
  "value": "0x0",
  "data": "0x0000000000000000000000000000000000000000000000000000000000000000fde8e4e1dca713016c518e31608606405234801651001657060080fd5b5061"
}

The registry MUST deploy each token bound account as an ERC-1167 minimal proxy with immutable constant data appended to the bytecode.

The deployed bytecode of each token bound account MUST have the following structure:

ERC-1167 Header (10 bytes) <implementation (address)> (20 bytes) ERC-1167 Footer (15 bytes) <salt (bytes32)> (32 bytes) <chainId (uint256)> (32 bytes) <tokenContract (address)> (32 bytes) <tokenId (uint256)> (32 bytes) For example, the token bound account with implementation address (0xbebebebebebebebebebebebebebebebebebebebe) salt (0), chain ID (1), token contract (0xcfccfccfccfccfccfccfccfccfccfccfccfccfcc) and token ID (123) would have the following deployed bytecode:

ebebebebebebebebebebebebe5af43d8230e930d91602b57fd5bf300000000000000000000000000

Account Interface

All token bound accounts SHOULD be created via the singleton registry. All token bound account implementations MUST implement ERC-165 interface detection. All token bound account implementations MUST implement ERC-1271 signature validation.

Execution Interface

All token bound accounts MUST implement an execution interface which allows valid signers to execute arbitrary operations on behalf of the account. Support for an execution interface MUST be signaled by the account using ERC-165 interface detection.

Build

$ forge build

Test