EIP-7950: Encode chain id with transaction hash
Way to encode a chain ID and transaction hash into a unique string format
| Authors | Lauri Peltonen (@microbecode) |
|---|---|
| Created | 2025-05-22 |
| Discussion Link | https://ethereum-magicians.org/t/a-new-standard-for-encoding-chain-id-transaction-hash/23782 |
| Requires | EIP-155 |
Table of Contents
Abstract
This standard proposes a way to encode the combination of a chain ID and a transaction hash into one string.
Motivation
Looking up a transaction by its hash always requires the context of the chain - a transaction hash alone is not enough to identify the used chain. If the chain information is included in the string itself, finding the right chain for the transaction is easy.
Such strings can then be used, for example, in a forwarder service that forwards to the correct blockchain explorer.
The chain id is included in some object formats, such as the transaction object inside the blockchain itself, but that object has a lot of unneeded data for our purposes.
Specification
The encoded string has three components:
- A chain ID, denoted as
chainId. The used chain id MUST be based on EIP-155 and the chain ID repository stated in that EIP. - A transaction hash, denoted as
txHash. The hash MUST include the0xprefix. - A static string
tx, acting as a type identifier.
The syntax is: chainId:txHash:tx.
An example for a transaction with hash 0xc55e2b90168af6972193c1f86fa4d7d7b31a29c156665d15b9cd48618b5177ef that was issued on chain ID 1 is: 1:0xc55e2b90168af6972193c1f86fa4d7d7b31a29c156665d15b9cd48618b5177ef:tx.
All of the characters are case-insensitive.
Rationale
The chain ID is the most important detail when routing queries based on this standard and is therefore the first element in the string. The transaction hash is the second most important element.
The suffix tx is used to differentiate from, for example, addresses. Without the tx it would remain unclear whether an encoded string refers to an address, a transaction hash or something else.
Security Considerations
This EIP does not introduce direct security risks. It is up to the external service providers (such as wallet developers and blockchain explorers) to decide how and if they want to incorporate this EIP.
Copyright
Copyright and related rights waived via CC0.
Citation
Please cite this document as:
Lauri Peltonen (@microbecode), "EIP-7950: Encode chain id with transaction hash [DRAFT]," Ethereum Improvement Proposals, no. 7950, May 2025. [Online serial]. Available: https://eips.ethereum.org/EIPS/eip-7950.