ENSIP-X: EOA/Fallback Chain Id

Abstract

This ENSIP specifies a way to set an EOA/Fallback address for a name. This allows for users to set one address to be used for all chains, or as a fallback for when a chain-specific address record is not set.

Motivation

With the rising interest and research around account abstraction, in addition to the maturation of the multi-chain ecosystem, there is a need for users to be able to set a single address to be used across all chains.

For a simple Externally Owned Account (EOA) user, this means setting their address once, and never having to worry about it again. For more advanced users, this means that chain-specific records can be used for smart-contract wallets, and an EOA can be specified as fallback.

This ENSIP introduces opt-in functionality that can be leveraged by both EOA and smart-contract wallets, and does not impact the existing functionality of ENS.

Specification

This ENSIP aims to extend the functionality introduced in ENSIP-9 and ENSIP-11 and simply relies on the same functionality.

CoinType for EOA

The standard CoinType for this proposed chain id is 2147483648.

This can be derived from 0x80000000 | 0 or evmChainIdToCoinType(0) , as per ENSIP-11.

Resolution Order

The resolution process remains as normal however now an extra lookup can be implemented client-side (or via proposed public resolver implementation).

The initial lookup is done for the chainId the user is currently on / interested in. For example for Optimism (EVM Chain Id 10), the initial lookup would be for coinType = 0x80000000 | 10.

If the lookup does not result in an address, a second lookup is done for the EOA Chain Id.

Proposed Implementation

There are multiple routes we considered around implementing this; client-side, or via a public resolver implementation.

For the smoothest implementation, leveraging the public resolver to handle this functionality for us seems ideal. This would mean no additional code is needed, and we can use the regular one-liners you are used to.

Public Resolver

The public resolver could choose to implement a fallback mechanism for EOA addresses. Such that when a coinType lookup occurs (for an EVM-compatible chain), and the resolver does not find an address record, it will return the EOA address.

This allows for additional flexibility allowing users to set a fallback address for all evm-compatible chains.

Backwards Compatibility

This proposal is backwards compatible with the existing addr(node, coinType) functionality, and simply adds additional fallback behavior.