88 lines
3.2 KiB
Markdown
88 lines
3.2 KiB
Markdown
# Deneb Light Client -- Sync Protocol
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**Notice**: This document is a work-in-progress for researchers and implementers.
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## Table of contents
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<!-- TOC -->
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<!-- START doctoc generated TOC please keep comment here to allow auto update -->
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<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
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- [Introduction](#introduction)
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- [Helper functions](#helper-functions)
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- [Modified `get_lc_execution_root`](#modified-get_lc_execution_root)
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- [Modified `is_valid_light_client_header`](#modified-is_valid_light_client_header)
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<!-- END doctoc generated TOC please keep comment here to allow auto update -->
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<!-- /TOC -->
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## Introduction
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This upgrade updates light client data to include the Deneb changes to the [`ExecutionPayload`](../beacon-chain.md) structure. It extends the [Capella Light Client specifications](../../capella/light-client/sync-protocol.md). The [fork document](./fork.md) explains how to upgrade existing Capella based deployments to Deneb.
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Additional documents describes the impact of the upgrade on certain roles:
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- [Full node](./full-node.md)
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- [Networking](./p2p-interface.md)
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## Helper functions
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### Modified `get_lc_execution_root`
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```python
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def get_lc_execution_root(header: LightClientHeader) -> Root:
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epoch = compute_epoch_at_slot(header.beacon.slot)
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# [New in Deneb]
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if epoch >= DENEB_FORK_EPOCH:
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return hash_tree_root(header.execution)
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# [Modified in Deneb]
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if epoch >= CAPELLA_FORK_EPOCH:
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execution_header = capella.ExecutionPayloadHeader(
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parent_hash=header.execution.parent_hash,
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fee_recipient=header.execution.fee_recipient,
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state_root=header.execution.state_root,
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receipts_root=header.execution.receipts_root,
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logs_bloom=header.execution.logs_bloom,
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prev_randao=header.execution.prev_randao,
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block_number=header.execution.block_number,
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gas_limit=header.execution.gas_limit,
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gas_used=header.execution.gas_used,
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timestamp=header.execution.timestamp,
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extra_data=header.execution.extra_data,
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base_fee_per_gas=header.execution.base_fee_per_gas,
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block_hash=header.execution.block_hash,
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transactions_root=header.execution.transactions_root,
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withdrawals_root=header.execution.withdrawals_root,
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)
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return hash_tree_root(execution_header)
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return Root()
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```
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### Modified `is_valid_light_client_header`
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```python
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def is_valid_light_client_header(header: LightClientHeader) -> bool:
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epoch = compute_epoch_at_slot(header.beacon.slot)
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# [New in Deneb]
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if epoch < DENEB_FORK_EPOCH:
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if header.execution.excess_data_gas != uint256(0):
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return False
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if epoch < CAPELLA_FORK_EPOCH:
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return (
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header.execution == ExecutionPayloadHeader()
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and header.execution_branch == [Bytes32() for _ in range(floorlog2(EXECUTION_PAYLOAD_INDEX))]
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)
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return is_valid_merkle_branch(
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leaf=get_lc_execution_root(header),
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branch=header.execution_branch,
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depth=floorlog2(EXECUTION_PAYLOAD_INDEX),
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index=get_subtree_index(EXECUTION_PAYLOAD_INDEX),
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root=header.beacon.body_root,
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)
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```
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