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Merge pull request #3657 from ralexstokes/eip-7251-spec-fixes
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Various spec fixes for EIP-7251
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@ralexstokes
ralexstokes authored Apr 8, 2024
2 parents e6092db + 8cf2fd5 commit dd2721f
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154 changes: 139 additions & 15 deletions specs/_features/eip7251/beacon-chain.md
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,8 @@
- [Extended Containers](#extended-containers)
- [`BeaconState`](#beaconstate)
- [`BeaconBlockBody`](#beaconblockbody)
- [`ExecutionPayload`](#executionpayload)
- [`ExecutionPayloadHeader`](#executionpayloadheader)
- [Helpers](#helpers)
- [Predicates](#predicates)
- [Updated `is_eligible_for_activation_queue`](#updated-is_eligible_for_activation_queue)
Expand Down Expand Up @@ -75,13 +77,14 @@
- [New `process_consolidation`](#new-process_consolidation)
- [Voluntary exits](#voluntary-exits)
- [Updated `process_voluntary_exit`](#updated-process_voluntary_exit)
- [Testing](#testing)

<!-- END doctoc generated TOC please keep comment here to allow auto update -->
<!-- /TOC -->

## Introduction

See [a modest proposal](https://notes.ethereum.org/@mikeneuder/increase-maxeb), the [diff view](https://github.com/michaelneuder/consensus-specs/pull/3/files) and
See [a modest proposal](https://notes.ethereum.org/@mikeneuder/increase-maxeb), the [diff view](https://github.com/michaelneuder/consensus-specs/pull/3/files) and
[security considerations](https://notes.ethereum.org/@fradamt/meb-increase-security).

*Note:* This specification is built upon [Deneb](../../deneb/beacon-chain.md).
Expand Down Expand Up @@ -136,6 +139,7 @@ The following values are (non-configurable) constants used throughout the specif

| Name | Value | Description |
| - | - | - |
| `MAX_WITHDRAWAL_REQUESTS_PER_PAYLOAD` | `uint64(16)` |
| `MAX_PARTIAL_WITHDRAWALS_PER_PAYLOAD` | `uint64(2**3)` (= 8) | Maximum amount of partial withdrawals allowed in each payload |

### State list lengths
Expand Down Expand Up @@ -282,12 +286,64 @@ class BeaconBlockBody(Container):
voluntary_exits: List[SignedVoluntaryExit, MAX_VOLUNTARY_EXITS]
sync_aggregate: SyncAggregate
# Execution
execution_payload: ExecutionPayload
execution_payload: ExecutionPayload
bls_to_execution_changes: List[SignedBLSToExecutionChange, MAX_BLS_TO_EXECUTION_CHANGES]
blob_kzg_commitments: List[KZGCommitment, MAX_BLOB_COMMITMENTS_PER_BLOCK]
consolidations: List[SignedConsolidation, MAX_CONSOLIDATIONS] # [New in EIP-7251]
```

#### `ExecutionPayload`

```python
class ExecutionPayload(Container):
# Execution block header fields
parent_hash: Hash32
fee_recipient: ExecutionAddress # 'beneficiary' in the yellow paper
state_root: Bytes32
receipts_root: Bytes32
logs_bloom: ByteVector[BYTES_PER_LOGS_BLOOM]
prev_randao: Bytes32 # 'difficulty' in the yellow paper
block_number: uint64 # 'number' in the yellow paper
gas_limit: uint64
gas_used: uint64
timestamp: uint64
extra_data: ByteList[MAX_EXTRA_DATA_BYTES]
base_fee_per_gas: uint256
# Extra payload fields
block_hash: Hash32 # Hash of execution block
transactions: List[Transaction, MAX_TRANSACTIONS_PER_PAYLOAD]
withdrawals: List[Withdrawal, MAX_WITHDRAWALS_PER_PAYLOAD]
blob_gas_used: uint64
excess_blob_gas: uint64
withdraw_requests: List[ExecutionLayerWithdrawRequest, MAX_WITHDRAWAL_REQUESTS_PER_PAYLOAD] # [New in EIP-7251]
```

#### `ExecutionPayloadHeader`

```python
class ExecutionPayloadHeader(Container):
# Execution block header fields
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
# Extra payload fields
block_hash: Hash32 # Hash of execution block
transactions_root: Root
withdrawals_root: Root
blob_gas_used: uint64
excess_blob_gas: uint64
withdraw_requests_root: Root # [New in EIP-7251]
```

## Helpers

### Predicates
Expand Down Expand Up @@ -386,7 +442,7 @@ def get_churn_limit(state: BeaconState) -> Gwei:
Return the churn limit for the current epoch.
"""
churn = max(
MIN_PER_EPOCH_CHURN_LIMIT_EIP7251,
MIN_PER_EPOCH_CHURN_LIMIT_EIP7251,
get_total_active_balance(state) // CHURN_LIMIT_QUOTIENT
)
return churn - churn % EFFECTIVE_BALANCE_INCREMENT
Expand Down Expand Up @@ -472,7 +528,6 @@ def queue_excess_active_balance(state: BeaconState, index: ValidatorIndex) -> No

#### New `compute_exit_epoch_and_update_churn`


```python
def compute_exit_epoch_and_update_churn(state: BeaconState, exit_balance: Gwei) -> Epoch:
earliest_exit_epoch = compute_activation_exit_epoch(get_current_epoch(state))
Expand Down Expand Up @@ -566,16 +621,23 @@ def process_epoch(state: BeaconState) -> None:
process_effective_balance_updates(state) # [Modified in EIP7251]
process_slashings_reset(state)
process_randao_mixes_reset(state)
process_historical_summaries_update(state)
process_participation_flag_updates(state)
process_sync_committee_updates(state)
```

#### Updated `process_registry_updates`

`process_registry_updates` uses the updated definition of `initiate_validator_exit`
and changes how the activation epochs are computed for eligible validators.

```python
def process_registry_updates(state: BeaconState) -> None:
# Process activation eligibility and ejections
for index, validator in enumerate(state.validators):
if is_eligible_for_activation_queue(validator):
validator.activation_eligibility_epoch = get_current_epoch(state) + 1

if (
is_active_validator(validator, get_current_epoch(state))
and validator.effective_balance <= EJECTION_BALANCE
Expand Down Expand Up @@ -607,7 +669,7 @@ def process_pending_balance_deposits(state: BeaconState) -> None:
state.pending_balance_deposits = state.pending_balance_deposits[next_deposit_index:]

if len(state.pending_balance_deposits) == 0:
state.deposit_balance_to_consume = 0
state.deposit_balance_to_consume = Gwei(0)
else:
state.deposit_balance_to_consume = available_for_processing - processed_amount
```
Expand Down Expand Up @@ -638,6 +700,8 @@ def process_pending_consolidations(state: BeaconState) -> None:

#### Updated `process_effective_balance_updates`

`process_effective_balance_updates` is updated with a new limit for the maximum effective balance.

```python
def process_effective_balance_updates(state: BeaconState) -> None:
# Update effective balances with hysteresis
Expand Down Expand Up @@ -760,7 +824,7 @@ def process_withdrawals(state: BeaconState, payload: ExecutionPayload) -> None:
state.next_withdrawal_validator_index = next_validator_index
```

#### Operations
#### Operations

##### Updated `process_operations`

Expand All @@ -779,14 +843,16 @@ def process_operations(state: BeaconState, body: BeaconBlockBody) -> None:
for_ops(body.deposits, process_deposit) # [Modified in EIP7251]
for_ops(body.voluntary_exits, process_voluntary_exit) # [Modified in EIP7251]
for_ops(body.bls_to_execution_changes, process_bls_to_execution_change)
for_ops(body.execution_payload.withdraw_requests, process_execution_layer_withdraw_request) # New in EIP7251
for_ops(body.consolidations, process_consolidation) # New in EIP7251
for_ops(body.execution_payload.withdraw_requests, process_execution_layer_withdraw_request) # [New in EIP7251]
for_ops(body.consolidations, process_consolidation) # [New in EIP7251]
```

##### Deposits

###### Updated `apply_deposit`

*NOTE*: `process_deposit` is updated with a new definition of `apply_deposit`.

```python
def apply_deposit(state: BeaconState,
pubkey: BLSPubkey,
Expand Down Expand Up @@ -819,7 +885,7 @@ def apply_deposit(state: BeaconState,
def is_valid_deposit_signature(pubkey: BLSPubkey,
withdrawal_credentials: Bytes32,
amount: uint64,
signature: BLSSignature) -> None:
signature: BLSSignature) -> bool:
deposit_message = DepositMessage(
pubkey=pubkey,
withdrawal_credentials=withdrawal_credentials,
Expand Down Expand Up @@ -862,7 +928,7 @@ def get_validator_from_deposit(pubkey: BLSPubkey, withdrawal_credentials: Bytes3
)
```

##### Withdrawals
##### Withdrawals

###### New `process_execution_layer_withdraw_request`

Expand All @@ -874,7 +940,7 @@ def process_execution_layer_withdraw_request(
amount = execution_layer_withdraw_request.amount
is_full_exit_request = amount == FULL_EXIT_REQUEST_AMOUNT

# If partial withdrawal queue is full, only full exits are processed
# If partial withdrawal queue is full, only full exits are processed
if len(state.pending_partial_withdrawals) >= PENDING_PARTIAL_WITHDRAWALS_LIMIT and not is_full_exit_request:
return

Expand Down Expand Up @@ -947,7 +1013,7 @@ def process_consolidation(state: BeaconState, signed_consolidation: SignedConsol
assert source_validator.exit_epoch == FAR_FUTURE_EPOCH
assert target_validator.exit_epoch == FAR_FUTURE_EPOCH
# Consolidations must specify an epoch when they become valid; they are not valid before then
assert current_epoch >= consolidation.epoch
assert current_epoch >= consolidation.epoch

# Verify the source and the target have Execution layer withdrawal credentials
assert has_execution_withdrawal_credential(source_validator)
Expand Down Expand Up @@ -989,12 +1055,70 @@ def process_voluntary_exit(state: BeaconState, signed_voluntary_exit: SignedVolu
assert get_current_epoch(state) >= voluntary_exit.epoch
# Verify the validator has been active long enough
assert get_current_epoch(state) >= validator.activation_epoch + SHARD_COMMITTEE_PERIOD
# Only exit validator if it has no pending withdrawals in the queue
assert get_pending_balance_to_withdraw(state, voluntary_exit.validator_index) == 0 # [New in EIP7251]
# Verify signature
domain = get_domain(state, DOMAIN_VOLUNTARY_EXIT, voluntary_exit.epoch)
domain = compute_domain(DOMAIN_VOLUNTARY_EXIT, CAPELLA_FORK_VERSION, state.genesis_validators_root)
signing_root = compute_signing_root(voluntary_exit, domain)
assert bls.Verify(validator.pubkey, signing_root, signed_voluntary_exit.signature)
# Only exit validator if it has no pending withdrawals in the queue
assert get_pending_balance_to_withdraw(state, voluntary_exit.validator_index) == 0 # [New in EIP7251]
# Initiate exit
initiate_validator_exit(state, voluntary_exit.validator_index)
```

## Testing

*Note*: The function `initialize_beacon_state_from_eth1` is modified for pure EIP-7251 testing only.

```python
def initialize_beacon_state_from_eth1(eth1_block_hash: Hash32,
eth1_timestamp: uint64,
deposits: Sequence[Deposit],
execution_payload_header: ExecutionPayloadHeader=ExecutionPayloadHeader()
) -> BeaconState:
fork = Fork(
previous_version=EIP7251_FORK_VERSION, # [Modified in EIP-7251] for testing only
current_version=EIP7251_FORK_VERSION, # [Modified in EIP-7251]
epoch=GENESIS_EPOCH,
)
state = BeaconState(
genesis_time=eth1_timestamp + GENESIS_DELAY,
fork=fork,
eth1_data=Eth1Data(block_hash=eth1_block_hash, deposit_count=uint64(len(deposits))),
latest_block_header=BeaconBlockHeader(body_root=hash_tree_root(BeaconBlockBody())),
randao_mixes=[eth1_block_hash] * EPOCHS_PER_HISTORICAL_VECTOR, # Seed RANDAO with Eth1 entropy
)

# Process deposits
leaves = list(map(lambda deposit: deposit.data, deposits))
for index, deposit in enumerate(deposits):
deposit_data_list = List[DepositData, 2**DEPOSIT_CONTRACT_TREE_DEPTH](*leaves[:index + 1])
state.eth1_data.deposit_root = hash_tree_root(deposit_data_list)
process_deposit(state, deposit)

# Process deposit balance updates
for deposit in state.pending_balance_deposits:
increase_balance(state, deposit.index, deposit.amount)
state.pending_balance_deposits = []

# Process activations
for index, validator in enumerate(state.validators):
balance = state.balances[index]
validator.effective_balance = min(balance - balance % EFFECTIVE_BALANCE_INCREMENT, MAX_EFFECTIVE_BALANCE)
if validator.effective_balance == MAX_EFFECTIVE_BALANCE:
validator.activation_eligibility_epoch = GENESIS_EPOCH
validator.activation_epoch = GENESIS_EPOCH

# Set genesis validators root for domain separation and chain versioning
state.genesis_validators_root = hash_tree_root(state.validators)

# Fill in sync committees
# Note: A duplicate committee is assigned for the current and next committee at genesis
state.current_sync_committee = get_next_sync_committee(state)
state.next_sync_committee = get_next_sync_committee(state)

# Initialize the execution payload header
# If empty, will initialize a chain that has not yet gone through the Merge transition
state.latest_execution_payload_header = execution_payload_header

return state
```
3 changes: 1 addition & 2 deletions specs/_features/eip7251/fork.md
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Expand Up @@ -131,8 +131,7 @@ def upgrade_to_eip7251(pre: deneb.BeaconState) -> BeaconState:
# Ensure early adopters of compounding credentials go through the activation churn
for index, validator in enumerate(post.validators):
if has_compounding_withdrawal_credential(validator):
queue_excess_active_balance(post, index)
queue_excess_active_balance(post, ValidatorIndex(index))

return post
```

73 changes: 73 additions & 0 deletions specs/_features/eip7251/validator.md
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@@ -0,0 +1,73 @@
# EIP-7251 -- Honest Validator

## Table of contents

<!-- TOC -->
<!-- START doctoc generated TOC please keep comment here to allow auto update -->
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->

- [Introduction](#introduction)
- [Prerequisites](#prerequisites)
- [Beacon chain responsibilities](#beacon-chain-responsibilities)
- [Block and sidecar proposal](#block-and-sidecar-proposal)
- [Constructing the `BeaconBlockBody`](#constructing-the-beaconblockbody)
- [ExecutionPayload](#executionpayload)

<!-- END doctoc generated TOC please keep comment here to allow auto update -->
<!-- /TOC -->

## Introduction

This document represents the changes to be made in the code of an "honest validator".

## Prerequisites

This document is an extension of the [Deneb -- Honest Validator](../deneb/validator.md) guide.
All behaviors and definitions defined in this document, and documents it extends, carry over unless explicitly noted or overridden.

All terminology, constants, functions, and protocol mechanics defined in the updated [Beacon Chain doc of EIP-7251](./beacon-chain.md) are requisite for this document and used throughout.
Please see related Beacon Chain doc before continuing and use them as a reference throughout.

## Beacon chain responsibilities

All validator responsibilities remain unchanged other than those noted below.

### Block and sidecar proposal

#### Constructing the `BeaconBlockBody`

##### ExecutionPayload

`prepare_execution_payload` is updated from the Deneb specs.

*Note*: In this section, `state` is the state of the slot for the block proposal _without_ the block yet applied.
That is, `state` is the `previous_state` processed through any empty slots up to the assigned slot using `process_slots(previous_state, slot)`.

*Note*: The only change to `prepare_execution_payload` is the new definition of `get_expected_withdrawals`.

```python
def prepare_execution_payload(state: BeaconState,
safe_block_hash: Hash32,
finalized_block_hash: Hash32,
suggested_fee_recipient: ExecutionAddress,
execution_engine: ExecutionEngine) -> Optional[PayloadId]:
# Verify consistency of the parent hash with respect to the previous execution payload header
parent_hash = state.latest_execution_payload_header.block_hash

# Set the forkchoice head and initiate the payload build process
withdrawals, _ = get_expected_withdrawals(state) # [Modified in EIP-7251]

payload_attributes = PayloadAttributes(
timestamp=compute_timestamp_at_slot(state, state.slot),
prev_randao=get_randao_mix(state, get_current_epoch(state)),
suggested_fee_recipient=suggested_fee_recipient,
withdrawals=withdrawals,
parent_beacon_block_root=hash_tree_root(state.latest_block_header),
)
return execution_engine.notify_forkchoice_updated(
head_block_hash=parent_hash,
safe_block_hash=safe_block_hash,
finalized_block_hash=finalized_block_hash,
payload_attributes=payload_attributes,
)
```

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