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EIP-7928 -- The Beacon Chain

Note: This document is a work-in-progress for researchers and implementers.

Introduction

Note: This specification is built upon Fulu and is under active development.

Custom types

Name SSZ equivalent Description
BlockAccessList ByteList[MAX_BYTES_PER_TRANSACTION] RLP encoded block access list

Extended Containers

ExecutionPayload

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class ExecutionPayload(Container):
    parent_hash: Hash32
    fee_recipient: ExecutionAddress
    state_root: Bytes32
    receipts_root: Bytes32
    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
    prev_randao: Bytes32
    block_number: uint64
    gas_limit: uint64
    gas_used: uint64
    timestamp: uint64
    extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
    base_fee_per_gas: uint256
    block_hash: Hash32
    transactions: List[Transaction, MAX_TRANSACTIONS_PER_PAYLOAD]
    withdrawals: List[Withdrawal, MAX_WITHDRAWALS_PER_PAYLOAD]
    blob_gas_used: uint64
    excess_blob_gas: uint64
    # [New in EIP7928]
    block_access_list: BlockAccessList

ExecutionPayloadHeader

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class ExecutionPayloadHeader(Container):
    parent_hash: Hash32
    fee_recipient: ExecutionAddress
    state_root: Bytes32
    receipts_root: Bytes32
    logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
    prev_randao: Bytes32
    block_number: uint64
    gas_limit: uint64
    gas_used: uint64
    timestamp: uint64
    extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
    base_fee_per_gas: uint256
    block_hash: Hash32
    transactions_root: Root
    withdrawals_root: Root
    blob_gas_used: uint64
    excess_blob_gas: uint64
    # [New in EIP7928]
    block_access_list_root: Root

NewPayloadRequest

Note: The NewPayloadRequest is unchanged. The block_access_list is included in the execution_payload field.

Beacon chain state transition function

Block processing

Execution payload

Modified process_execution_payload
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def process_execution_payload(
    state: BeaconState, body: BeaconBlockBody, execution_engine: ExecutionEngine
) -> None:
    payload = body.execution_payload

    # Verify consistency of the parent hash with respect to the previous execution payload header
    assert payload.parent_hash == state.latest_execution_payload_header.block_hash
    # Verify prev_randao
    assert payload.prev_randao == get_randao_mix(state, get_current_epoch(state))
    # Verify timestamp
    assert payload.timestamp == compute_time_at_slot(state, state.slot)
    # Verify commitments are under limit
    assert (
        len(body.blob_kzg_commitments)
        <= get_blob_parameters(get_current_epoch(state)).max_blobs_per_block
    )
    # Verify the execution payload is valid
    versioned_hashes = [
        kzg_commitment_to_versioned_hash(commitment) for commitment in body.blob_kzg_commitments
    ]
    assert execution_engine.verify_and_notify_new_payload(
        NewPayloadRequest(
            execution_payload=payload,
            versioned_hashes=versioned_hashes,
            parent_beacon_block_root=state.latest_block_header.parent_root,
            execution_requests=body.execution_requests,
        )
    )
    # Cache execution payload header
    state.latest_execution_payload_header = ExecutionPayloadHeader(
        parent_hash=payload.parent_hash,
        fee_recipient=payload.fee_recipient,
        state_root=payload.state_root,
        receipts_root=payload.receipts_root,
        logs_bloom=payload.logs_bloom,
        prev_randao=payload.prev_randao,
        block_number=payload.block_number,
        gas_limit=payload.gas_limit,
        gas_used=payload.gas_used,
        timestamp=payload.timestamp,
        extra_data=payload.extra_data,
        base_fee_per_gas=payload.base_fee_per_gas,
        block_hash=payload.block_hash,
        transactions_root=hash_tree_root(payload.transactions),
        withdrawals_root=hash_tree_root(payload.withdrawals),
        blob_gas_used=payload.blob_gas_used,
        excess_blob_gas=payload.excess_blob_gas,
        # [New in EIP7928]
        block_access_list_root=hash_tree_root(payload.block_access_list),
    )