Abstract
This EIP defines a migration process of EIP-2718 Recursive-Length Prefix (RLP) receipts to Simple Serialize (SSZ)
Motivation
RLP receipts have a number of shortcomings:
Limited proving support: Due to receipt data being linearly hashed as part of the receipts_root Merkle-Patricia Trie (MPT), it is not possible to efficiently proof individual parts of receipts, such as logs. Requiring the full receipt data to be present can be prohibitive for smart contract based applications such as L2 fraud proofs or client applications verifying log data.
Incomplete data: JSON-RPC provides from, gasUsed, and contractAddress fields for receipts, but the on-chain receipt does not contain the required information to verify them.
This EIP defines a universal receipt format based on SSZ to address these concerns.
Specification
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC 2119 and RFC 8174.
Existing definitions
Definitions from existing specifications that are used throughout this document are replicated here for reference.
Logs
Logs are represented as an SSZ Container.
| Name |
Value |
Description |
MAX_TOPICS_PER_LOG |
4 |
LOG0 through LOG4 opcodes allow 0-4 topics per log |
class Log(Container):
address: ExecutionAddress
topics: List[Bytes32, MAX_TOPICS_PER_LOG]
data: ProgressiveByteList
Receipts
New receipts use a normalized SSZ representation.
class Receipt(CompatibleUnion({
0x01: BasicReceipt,
0x02: CreateReceipt,
0x03: SetCodeReceipt,
})):
pass
Basic receipts
This receipt is emitted for these transactions:
class BasicReceipt(
ProgressiveContainer(active_fields=[1, 1, 0, 1, 1])
):
from_: ExecutionAddress
gas_used: GasAmount
logs: ProgressiveList[Log]
status: boolean
Create receipts
This receipt is emitted for these transactions:
class CreateReceipt(
ProgressiveContainer(active_fields=[1, 1, 1, 1, 1])
):
from_: ExecutionAddress
gas_used: GasAmount
contract_address: ExecutionAddress
logs: ProgressiveList[Log]
status: boolean
EIP-7702 set code receipts
This receipt is emitted for these transactions:
class SetCodeReceipt(
ProgressiveContainer(active_fields=[1, 1, 0, 1, 1, 1])
):
from_: ExecutionAddress
gas_used: GasAmount
logs: ProgressiveList[Log]
status: boolean
authorities: ProgressiveList[ExecutionAddress]
Receipt construction
Receipts are constructed as follows.
| Field |
Description |
from |
The transaction sender's address |
gas_used |
How much gas this individual transaction used |
contract_address |
For transactions deploying a contract, the new contract address. Present only in CreateReceipt |
logs |
Logs emitted during transaction execution |
status |
EIP-658 transaction status code |
authorities |
For transactions with an authorization list, the list of EIP-7702 authority addresses. Non-successful authorizations are represented with an all-zero address |
The logs_bloom, intermediate state root (Homestead scheme), and cumulative_gas_used (pre EIP-8116) fields are not present in SSZ receipts.
Execution block header changes
The execution block header's receipts-root is transitioned from MPT to SSZ.
receipts = ProgressiveList[Receipt](
receipt_0, receipt_1, receipt_2, ...)
block_header.receipts_root = receipts.hash_tree_root()
JSON-RPC API
Transaction receipt objects in the context of the JSON-RPC API are extended to include:
authorities: Array of DATA|null - Array of DATA entries each containing 20 Bytes, corresponding to the receipt's authorities field
The logsBloom field is no longer returned for new receipts. It continues to be returned for historical receipts conforming to earlier schemes.
from, gasUsed, and contractAddress are already provided via JSON-RPC and are left unchanged. For BasicReceipt and SetCodeReceipt, contractAddress will be null as these receipt types do not contain the contract_address field. logIndex indicates the log index position in the individual receipt (rather than the entire block), as defined in EIP-8116.
Consensus ExecutionPayload changes
When building a consensus ExecutionPayload, the receipts_root is now based on the Receipt type, changing the type of receipts_root from an MPT Hash32 to an SSZ Root.
class ExecutionPayload(...):
...
receipts_root: Root
...
class ExecutionPayloadHeader(...):
...
receipts_root: Root
...
payload_header.receipts_root = payload.receipts_root
Rationale
Forward compatibility
All receipts share the same Merkle tree shape with a stable generalized index (gindex) assigned to each field. Future transaction features can introduce additional receipt fields or drop existing fields without breaking verifiers.
Verifier improvements
Committing to from, contract_address and authorities in the receipt allows efficient verification without the expensive ecrecover mechanism. This allows future EIPs to change how these addresses are computed without breaking verifiers, e.g., when future signature schemes are introduced.
Execution client improvements
Execution Layer implementations no longer need access to the transaction and additional indices when serving receipts based on SSZ.
Backwards Compatibility
Applications that rely on the replaced MPT receipts_root in the block header require migration to the SSZ receipts_root.
RLP and SSZ receipts may clash when encoded. It is essential to use only a single format within one channel. When requesting receipts by hash over the network, the block header corresponding to the containing receipts root can be consulted to identify the underlying fork.
Security Considerations
None
Copyright
Copyright and related rights waived via CC0.
