222 lines
6.6 KiB
Markdown
222 lines
6.6 KiB
Markdown
# EIP6800 -- The Beacon Chain
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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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- [Custom types](#custom-types)
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- [Preset](#preset)
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- [Execution](#execution)
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- [Containers](#containers)
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- [Extended containers](#extended-containers)
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- [`ExecutionPayload`](#executionpayload)
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- [`ExecutionPayloadHeader`](#executionpayloadheader)
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- [New containers](#new-containers)
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- [`SuffixStateDiff`](#suffixstatediff)
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- [`StemStateDiff`](#stemstatediff)
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- [`IPAProof`](#ipaproof)
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- [`VerkleProof`](#verkleproof)
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- [`ExecutionWitness`](#executionwitness)
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- [Beacon chain state transition function](#beacon-chain-state-transition-function)
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- [Block processing](#block-processing)
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- [Execution payload](#execution-payload)
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- [`process_execution_payload`](#process_execution_payload)
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- [Testing](#testing)
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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 adds transaction execution to the beacon chain as part of the eip6800 upgrade.
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## Custom types
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| Name | SSZ equivalent | Description |
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| - | - | - |
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| `BanderwagonGroupElement` | `Bytes32` | |
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| `BanderwagonFieldElement` | `Bytes32` | |
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| `Stem` | `Bytes31` | |
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## Preset
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### Execution
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| Name | Value |
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| - | - |
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| `MAX_STEMS` | `uint64(2**16)` (= 65,536) |
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| `MAX_COMMITMENTS_PER_STEM` | `uint64(33)` |
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| `VERKLE_WIDTH` | `uint64(2**8)` (= 256) |
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| `IPA_PROOF_DEPTH` | `uint64(2**3)` (= 8) |
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## Containers
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### Extended containers
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#### `ExecutionPayload`
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```python
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class ExecutionPayload(Container):
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# Execution block header fields
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parent_hash: Hash32
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fee_recipient: ExecutionAddress # 'beneficiary' in the yellow paper
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state_root: Bytes32
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receipts_root: Bytes32
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logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
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prev_randao: Bytes32 # 'difficulty' in the yellow paper
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block_number: uint64 # 'number' in the yellow paper
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gas_limit: uint64
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gas_used: uint64
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timestamp: uint64
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extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
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base_fee_per_gas: uint256
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# Extra payload fields
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block_hash: Hash32 # Hash of execution block
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transactions: List[Transaction, MAX_TRANSACTIONS_PER_PAYLOAD]
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withdrawals: List[Withdrawal, MAX_WITHDRAWALS_PER_PAYLOAD]
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blob_gas_used: uint64
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excess_blob_gas: uint64
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execution_witness: ExecutionWitness # [New in EIP6800]
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```
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#### `ExecutionPayloadHeader`
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```python
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class ExecutionPayloadHeader(Container):
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# Execution block header fields
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parent_hash: Hash32
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fee_recipient: ExecutionAddress
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state_root: Bytes32
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receipts_root: Bytes32
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logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
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prev_randao: Bytes32
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block_number: uint64
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gas_limit: uint64
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gas_used: uint64
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timestamp: uint64
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extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
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base_fee_per_gas: uint256
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# Extra payload fields
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block_hash: Hash32 # Hash of execution block
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transactions_root: Root
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withdrawals_root: Root
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blob_gas_used: uint64
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excess_data_gas: uint64
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execution_witness_root: Root # [New in EIP6800]
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```
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### New containers
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#### `SuffixStateDiff`
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```python
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class SuffixStateDiff(Container):
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suffix: Bytes1
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# Null means not currently present
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current_value: Optional[Bytes32]
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# Null means value not updated
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new_value: Optional[Bytes32]
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```
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*Note*: on the Kaustinen testnet, `new_value` is omitted from the container.
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#### `StemStateDiff`
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```python
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class StemStateDiff(Container):
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stem: Stem
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# Valid only if list is sorted by suffixes
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suffix_diffs: List[SuffixStateDiff, VERKLE_WIDTH]
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```
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#### `IPAProof`
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```python
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class IPAProof(Container):
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cl: Vector[BanderwagonGroupElement, IPA_PROOF_DEPTH]
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cr: Vector[BanderwagonGroupElement, IPA_PROOF_DEPTH]
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final_evaluation = BanderwagonFieldElement
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```
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#### `VerkleProof`
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```python
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class VerkleProof(Container):
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other_stems: List[Bytes31, MAX_STEMS]
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depth_extension_present: ByteList[MAX_STEMS]
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commitments_by_path: List[BanderwagonGroupElement, MAX_STEMS * MAX_COMMITMENTS_PER_STEM]
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d: BanderwagonGroupElement
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ipa_proof: IPAProof
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```
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#### `ExecutionWitness`
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```python
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class ExecutionWitness(Container):
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state_diff: List[StemStateDiff, MAX_STEMS]
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verkle_proof: VerkleProof
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```
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## Beacon chain state transition function
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### Block processing
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#### Execution payload
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##### `process_execution_payload`
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```python
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def process_execution_payload(state: BeaconState, body: BeaconBlockBody, execution_engine: ExecutionEngine) -> None:
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payload = body.execution_payload
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# Verify consistency of the parent hash with respect to the previous execution payload header
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assert payload.parent_hash == state.latest_execution_payload_header.block_hash
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# Verify prev_randao
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assert payload.prev_randao == get_randao_mix(state, get_current_epoch(state))
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# Verify timestamp
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assert payload.timestamp == compute_timestamp_at_slot(state, state.slot)
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# Verify commitments are under limit
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assert len(body.blob_kzg_commitments) <= MAX_BLOBS_PER_BLOCK
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# Verify the execution payload is valid
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# Pass `versioned_hashes` to Execution Engine
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# Pass `parent_beacon_block_root` to Execution Engine
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versioned_hashes = [kzg_commitment_to_versioned_hash(commitment) for commitment in body.blob_kzg_commitments]
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assert execution_engine.verify_and_notify_new_payload(
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NewPayloadRequest(
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execution_payload=payload,
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versioned_hashes=versioned_hashes,
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parent_beacon_block_root=state.latest_block_header.parent_root,
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)
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)
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# Cache execution payload header
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state.latest_execution_payload_header = ExecutionPayloadHeader(
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parent_hash=payload.parent_hash,
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fee_recipient=payload.fee_recipient,
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state_root=payload.state_root,
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receipts_root=payload.receipts_root,
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logs_bloom=payload.logs_bloom,
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prev_randao=payload.prev_randao,
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block_number=payload.block_number,
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gas_limit=payload.gas_limit,
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gas_used=payload.gas_used,
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timestamp=payload.timestamp,
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extra_data=payload.extra_data,
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base_fee_per_gas=payload.base_fee_per_gas,
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block_hash=payload.block_hash,
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transactions_root=hash_tree_root(payload.transactions),
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withdrawals_root=hash_tree_root(payload.withdrawals),
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excess_data_gas=payload.excess_data_gas,
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execution_witness_root=hash_tree_root(payload.execution_witness), # [New in EIP6800]
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)
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```
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## Testing
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TBD
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