ERC-8340: Transaction Metadata Encoding

chunter · July 15, 2026, 11:08pm

Discussion for metadata encoding which is designed to work with EIP 8130 but compatible with any transaction type / transport method.

github.com/ethereum/ERCs

Add ERC: Transaction Metadata Encoding

master ← chunter-cb:erc-8130-metadata-encoding

opened 10:45PM - 15 Jul 26 UTC

chunter-cb

+465 -0

## Abstract [EIP-8130](https://github.com/ethereum/EIPs/blob/master/EIPS/eip-81…30.md) adds an optional, opaque `metadata` field to its account-abstraction transaction type but leaves the byte layout to a companion specification. This ERC defines that layout. `metadata` is a single deterministic [CBOR](https://www.rfc-editor.org/rfc/rfc8949) value: a text string (memo), a byte string (commitment digest), a map of reserved keys (attribution, memo, commitment, scope), or an array of these. The map keys are interoperable with ERC-8021 schema 2, extended with keys for offchain commitments and call scoping. Any value MAY be replaced by a salted commitment, recursively, giving selective disclosure with a single primitive; the ERC also specifies the offchain proof package, verification, and delivery protocol, plus an [ERC-5792](https://github.com/ethereum/ERCs/blob/master/ERCS/erc-5792.md) `metadata` capability that supersedes `dataSuffix`. ## Motivation EIP-8130's `metadata` field is opaque bytes; without a shared structure every producer invents its own framing and no indexer can read across them. This ERC provides a compact, deterministic, ERC-8021-compatible encoding that covers attribution, memos, per-call scope, and privacy-preserving commitments to offchain data. ## Notes - New draft ERC; a single file is added under `ERCS/`. - Depends on ERC-5792 and EIP-8130 (`requires: 5792, 8130`). - Discussion: https://ethereum-magicians.org/t/erc-transaction-metadata-encoding-for-eip-8130 I understand an editor will assign the ERC number; I will rename the file to match the PR number.