3.2 KiB
3.2 KiB
EIP4844 Light Client -- Sync Protocol
Notice: This document is a work-in-progress for researchers and implementers.
Table of contents
Introduction
This upgrade updates light client data to include the EIP4844 changes to the ExecutionPayload structure. It extends the Capella Light Client specifications. The fork document explains how to upgrade existing Capella based deployments to EIP4844.
Additional documents describes the impact of the upgrade on certain roles:
Helper functions
Modified get_lc_execution_root
def get_lc_execution_root(header: LightClientHeader) -> Root:
epoch = compute_epoch_at_slot(header.beacon.slot)
# [New in EIP4844]
if epoch >= EIP4844_FORK_EPOCH:
return hash_tree_root(header.execution)
# [Modified in EIP4844]
if epoch >= CAPELLA_FORK_EPOCH:
execution_header = capella.ExecutionPayloadHeader(
parent_hash=header.execution.parent_hash,
fee_recipient=header.execution.fee_recipient,
state_root=header.execution.state_root,
receipts_root=header.execution.receipts_root,
logs_bloom=header.execution.logs_bloom,
prev_randao=header.execution.prev_randao,
block_number=header.execution.block_number,
gas_limit=header.execution.gas_limit,
gas_used=header.execution.gas_used,
timestamp=header.execution.timestamp,
extra_data=header.execution.extra_data,
base_fee_per_gas=header.execution.base_fee_per_gas,
block_hash=header.execution.block_hash,
transactions_root=header.execution.transactions_root,
withdrawals_root=header.execution.withdrawals_root,
)
return hash_tree_root(execution_header)
return Root()
Modified is_valid_light_client_header
def is_valid_light_client_header(header: LightClientHeader) -> bool:
epoch = compute_epoch_at_slot(header.beacon.slot)
# [New in EIP4844]
if epoch < EIP4844_FORK_EPOCH:
if header.execution.excess_data_gas != uint256(0):
return False
if epoch < CAPELLA_FORK_EPOCH:
return (
header.execution == ExecutionPayloadHeader()
and header.execution_branch == [Bytes32() for _ in range(floorlog2(EXECUTION_PAYLOAD_INDEX))]
)
return is_valid_merkle_branch(
leaf=get_lc_execution_root(header),
branch=header.execution_branch,
depth=floorlog2(EXECUTION_PAYLOAD_INDEX),
index=get_subtree_index(EXECUTION_PAYLOAD_INDEX),
root=header.beacon.body_root,
)