EIP155 Namespace, aka EVM Chains - Chains

CAIP-2

For context, see the CAIP-2 specification.

Rationale

The chain ID defined in EIP155 is the most widely used chain identifier in the Ethereum ecosystem known to the authors. It optimizes for uniqueness and its usage for replay protection has helped it achieve wide adoption. Unique network IDs can be self-registered in the ethereum-lists/chains registry.

Syntax

For reference, The format of reference currently specified in EIP155 is an unsigned integer of type UINT256, which is 64 characters long in hexadecimal notation. That said, the longest chainId registered in the registry is 15 characters long, and compatibility with major wallets and common tooling in the Ethereum ecosystem is endangered when chainIds exceed 55 bits, so implementers are encouraged to observe the much shorter profile defined in EIP-2294 in contexts where longer chainIds need to be supported.

Resolution Method

To resolve a blockchain reference for the EIP155 namespace, make a JSON-RPC request to a blockchain node with method eth_chainId, for example:

// Request
{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "eth_chainId",
  "params": []
}

// Response
{
  "id": 1,
  "jsonrpc": "2.0",
  "result": "0x1"
}

The response will return a base-16-encoded integer that should be converted to base 10 to format an EIP155-compatible blockchain reference.

Test Cases

This is a list of manually composed examples

# Ethereum mainnet
eip155:1

# Görli
eip155:5

# Auxilium Network Mainnet
eip155:28945486

References

• EIP155: Ethereum Improvement Proposal specifying generation and validation of ChainIDs
• ethereum-lists/chains: An open registry for eip155 network operators to claim a unique chainID and self-publish RPC/node information for them.
• ERC20: Basic [aka Fungible] Token Standard
• ERC721: Non-Fungible Token Standard

Rights

Copyright and related rights waived via CC0.

Citation

Please cite this document as:

Simon Warta, ligi, Pedro Gomes, Antoine Herzog, Joel Thorstensson, "namespaces/eip155-caip2: EIP155 Namespace, aka EVM Chains - Chains [DRAFT]," Chain Agnostic Namespaces, eip155-caip2, December 2019 / March 2022. [Online serial]. Available: https://github.com/ChainAgnostic/namespaces/eip155-caip2.md