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# Electra -- The Beacon Chain
**Notice**: This document is a work-in-progress for researchers and implementers.
## 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)
- [Constants](#constants)
- [Misc](#misc)
- [Withdrawal prefixes](#withdrawal-prefixes)
- [Execution layer triggered requests](#execution-layer-triggered-requests)
- [Preset](#preset)
- [Gwei values](#gwei-values)
- [Rewards and penalties](#rewards-and-penalties)
- [State list lengths](#state-list-lengths)
- [Max operations per block](#max-operations-per-block)
- [Execution](#execution)
- [Withdrawals processing](#withdrawals-processing)
- [Pending deposits processing](#pending-deposits-processing)
- [Configuration](#configuration)
- [Execution](#execution-1)
- [Validator cycle](#validator-cycle)
- [Containers](#containers)
- [New containers](#new-containers)
- [`PendingDeposit`](#pendingdeposit)
- [`PendingPartialWithdrawal`](#pendingpartialwithdrawal)
- [`PendingConsolidation`](#pendingconsolidation)
- [`DepositRequest`](#depositrequest)
- [`WithdrawalRequest`](#withdrawalrequest)
- [`ConsolidationRequest`](#consolidationrequest)
- [`ExecutionRequests`](#executionrequests)
- [`SingleAttestation`](#singleattestation)
- [Modified Containers](#modified-containers)
- [`AttesterSlashing`](#attesterslashing)
- [`BeaconBlockBody`](#beaconblockbody)
- [Extended Containers](#extended-containers)
- [`Attestation`](#attestation)
- [`IndexedAttestation`](#indexedattestation)
- [`BeaconState`](#beaconstate)
- [Helper functions](#helper-functions)
- [Predicates](#predicates)
- [Modified `compute_proposer_index`](#modified-compute_proposer_index)
- [Modified `is_eligible_for_activation_queue`](#modified-is_eligible_for_activation_queue)
- [New `is_compounding_withdrawal_credential`](#new-is_compounding_withdrawal_credential)
- [New `has_compounding_withdrawal_credential`](#new-has_compounding_withdrawal_credential)
- [New `has_execution_withdrawal_credential`](#new-has_execution_withdrawal_credential)
- [Modified `is_fully_withdrawable_validator`](#modified-is_fully_withdrawable_validator)
- [Modified `is_partially_withdrawable_validator`](#modified-is_partially_withdrawable_validator)
- [Misc](#misc-1)
- [New `get_committee_indices`](#new-get_committee_indices)
- [New `get_max_effective_balance`](#new-get_max_effective_balance)
- [Beacon state accessors](#beacon-state-accessors)
- [New `get_balance_churn_limit`](#new-get_balance_churn_limit)
- [New `get_activation_exit_churn_limit`](#new-get_activation_exit_churn_limit)
- [New `get_consolidation_churn_limit`](#new-get_consolidation_churn_limit)
- [New `get_pending_balance_to_withdraw`](#new-get_pending_balance_to_withdraw)
- [Modified `get_attesting_indices`](#modified-get_attesting_indices)
- [Modified `get_next_sync_committee_indices`](#modified-get_next_sync_committee_indices)
- [Beacon state mutators](#beacon-state-mutators)
- [Modified `initiate_validator_exit`](#modified-initiate_validator_exit)
- [New `switch_to_compounding_validator`](#new-switch_to_compounding_validator)
- [New `queue_excess_active_balance`](#new-queue_excess_active_balance)
- [New `compute_exit_epoch_and_update_churn`](#new-compute_exit_epoch_and_update_churn)
- [New `compute_consolidation_epoch_and_update_churn`](#new-compute_consolidation_epoch_and_update_churn)
- [Modified `slash_validator`](#modified-slash_validator)
- [Beacon chain state transition function](#beacon-chain-state-transition-function)
- [Epoch processing](#epoch-processing)
- [Modified `process_epoch`](#modified-process_epoch)
- [Modified `process_registry_updates`](#modified-process_registry_updates)
- [Modified `process_slashings`](#modified-process_slashings)
- [New `apply_pending_deposit`](#new-apply_pending_deposit)
- [New `process_pending_deposits`](#new-process_pending_deposits)
- [New `process_pending_consolidations`](#new-process_pending_consolidations)
- [Modified `process_effective_balance_updates`](#modified-process_effective_balance_updates)
- [Execution engine](#execution-engine)
- [Request data](#request-data)
- [Modified `NewPayloadRequest`](#modified-newpayloadrequest)
- [Engine APIs](#engine-apis)
- [Modified `is_valid_block_hash`](#modified-is_valid_block_hash)
- [Modified `notify_new_payload`](#modified-notify_new_payload)
- [Modified `verify_and_notify_new_payload`](#modified-verify_and_notify_new_payload)
- [Block processing](#block-processing)
- [Withdrawals](#withdrawals)
- [Modified `get_expected_withdrawals`](#modified-get_expected_withdrawals)
- [Modified `process_withdrawals`](#modified-process_withdrawals)
- [Execution payload](#execution-payload)
- [New `get_execution_requests_list`](#new-get_execution_requests_list)
- [Modified `process_execution_payload`](#modified-process_execution_payload)
- [Operations](#operations)
- [Modified `process_operations`](#modified-process_operations)
- [Attestations](#attestations)
- [Modified `process_attestation`](#modified-process_attestation)
- [Deposits](#deposits)
- [Modified `get_validator_from_deposit`](#modified-get_validator_from_deposit)
- [Modified `add_validator_to_registry`](#modified-add_validator_to_registry)
- [Modified `apply_deposit`](#modified-apply_deposit)
- [New `is_valid_deposit_signature`](#new-is_valid_deposit_signature)
- [Modified `process_deposit`](#modified-process_deposit)
- [Voluntary exits](#voluntary-exits)
- [Modified `process_voluntary_exit`](#modified-process_voluntary_exit)
- [Execution layer withdrawal requests](#execution-layer-withdrawal-requests)
- [New `process_withdrawal_request`](#new-process_withdrawal_request)
- [Deposit requests](#deposit-requests)
- [New `process_deposit_request`](#new-process_deposit_request)
- [Execution layer consolidation requests](#execution-layer-consolidation-requests)
- [New `is_valid_switch_to_compounding_request`](#new-is_valid_switch_to_compounding_request)
- [New `process_consolidation_request`](#new-process_consolidation_request)
<!-- END doctoc generated TOC please keep comment here to allow auto update -->
<!-- /TOC -->
## Introduction
Electra is a consensus-layer upgrade containing a number of features. Including:
* [EIP-6110](https://eips.ethereum.org/EIPS/eip-6110): Supply validator deposits on chain
* [EIP-7002](https://eips.ethereum.org/EIPS/eip-7002): Execution layer triggerable exits
* [EIP-7251](https://eips.ethereum.org/EIPS/eip-7251): Increase the MAX_EFFECTIVE_BALANCE
* [EIP-7549](https://eips.ethereum.org/EIPS/eip-7549): Move committee index outside Attestation
* [EIP-7691](https://eips.ethereum.org/EIPS/eip-7691): Blob throughput increase
*Note:* This specification is built upon [Deneb](../deneb/beacon-chain.md) and is under active development.
## Constants
The following values are (non-configurable) constants used throughout the specification.
### Misc
| Name | Value | Description |
| - | - | - |
| `UNSET_DEPOSIT_REQUESTS_START_INDEX` | `uint64(2**64 - 1)` | *[New in Electra:EIP6110]* Value which indicates no start index has been assigned |
| `FULL_EXIT_REQUEST_AMOUNT` | `uint64(0)` | *[New in Electra:EIP7002]* Withdrawal amount used to signal a full validator exit |
### Withdrawal prefixes
| Name | Value | Description |
| - | - | - |
| `COMPOUNDING_WITHDRAWAL_PREFIX` | `Bytes1('0x02')` | *[New in Electra:EIP7251]* Withdrawal credential prefix for a compounding validator |
### Execution layer triggered requests
| Name | Value |
| - | - |
| `DEPOSIT_REQUEST_TYPE` | `Bytes1('0x00')` |
| `WITHDRAWAL_REQUEST_TYPE` | `Bytes1('0x01')` |
| `CONSOLIDATION_REQUEST_TYPE` | `Bytes1('0x02')` |
## Preset
### Gwei values
| Name | Value | Description |
| - | - | - |
| `MIN_ACTIVATION_BALANCE` | `Gwei(2**5 * 10**9)` (= 32,000,000,000) | *[New in Electra:EIP7251]* Minimum balance for a validator to become active |
| `MAX_EFFECTIVE_BALANCE_ELECTRA` | `Gwei(2**11 * 10**9)` (= 2048,000,000,000) | *[New in Electra:EIP7251]* Maximum effective balance for a compounding validator |
### Rewards and penalties
| Name | Value |
| - | - |
| `MIN_SLASHING_PENALTY_QUOTIENT_ELECTRA` | `uint64(2**12)` (= 4,096) |
| `WHISTLEBLOWER_REWARD_QUOTIENT_ELECTRA` | `uint64(2**12)` (= 4,096) |
### State list lengths
| Name | Value | Unit |
| - | - | :-: |
| `PENDING_DEPOSITS_LIMIT` | `uint64(2**27)` (= 134,217,728) | pending deposits |
| `PENDING_PARTIAL_WITHDRAWALS_LIMIT` | `uint64(2**27)` (= 134,217,728) | pending partial withdrawals |
| `PENDING_CONSOLIDATIONS_LIMIT` | `uint64(2**18)` (= 262,144) | pending consolidations |
### Max operations per block
| Name | Value |
| - | - |
| `MAX_ATTESTER_SLASHINGS_ELECTRA` | `2**0` (= 1) |
| `MAX_ATTESTATIONS_ELECTRA` | `2**3` (= 8) |
### Execution
| Name | Value | Description |
| - | - | - |
| `MAX_DEPOSIT_REQUESTS_PER_PAYLOAD` | `uint64(2**13)` (= 8,192) | *[New in Electra:EIP6110]* Maximum number of execution layer deposit requests in each payload |
| `MAX_WITHDRAWAL_REQUESTS_PER_PAYLOAD` | `uint64(2**4)` (= 16)| *[New in Electra:EIP7002]* Maximum number of execution layer withdrawal requests in each payload |
| `MAX_CONSOLIDATION_REQUESTS_PER_PAYLOAD` | `uint64(2**1)` (= 2) | *[New in Electra:EIP7251]* Maximum number of execution layer consolidation requests in each payload |
### Withdrawals processing
| Name | Value | Description |
| - | - | - |
| `MAX_PENDING_PARTIALS_PER_WITHDRAWALS_SWEEP` | `uint64(2**3)` (= 8)| *[New in Electra:EIP7002]* Maximum number of pending partial withdrawals to process per payload |
### Pending deposits processing
| Name | Value | Description |
| - | - | - |
| `MAX_PENDING_DEPOSITS_PER_EPOCH` | `uint64(2**4)` (= 16)| *[New in Electra:EIP6110]* Maximum number of pending deposits to process per epoch |
## Configuration
### Execution
| Name | Value | Description |
| - | - | - |
| `TARGET_BLOBS_PER_BLOCK_ELECTRA` | `uint64(6)` | *[New in Electra:EIP7691]* Target number of blobs in a single block limited by `MAX_BLOBS_PER_BLOCK_ELECTRA` |
| `MAX_BLOBS_PER_BLOCK_ELECTRA` | `uint64(9)` | *[New in Electra:EIP7691]* Maximum number of blobs in a single block limited by `MAX_BLOB_COMMITMENTS_PER_BLOCK` |
### Validator cycle
| Name | Value |
| - | - |
| `MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA` | `Gwei(2**7 * 10**9)` (= 128,000,000,000) | # Equivalent to 4 32 ETH validators
| `MAX_PER_EPOCH_ACTIVATION_EXIT_CHURN_LIMIT` | `Gwei(2**8 * 10**9)` (= 256,000,000,000) |
## Containers
### New containers
#### `PendingDeposit`
*Note*: The container is new in EIP7251.
```python
class PendingDeposit(Container):
pubkey: BLSPubkey
withdrawal_credentials: Bytes32
amount: Gwei
signature: BLSSignature
slot: Slot
```
#### `PendingPartialWithdrawal`
*Note*: The container is new in EIP7251.
```python
class PendingPartialWithdrawal(Container):
index: ValidatorIndex
amount: Gwei
withdrawable_epoch: Epoch
```
#### `PendingConsolidation`
*Note*: The container is new in EIP7251.
```python
class PendingConsolidation(Container):
source_index: ValidatorIndex
target_index: ValidatorIndex
```
#### `DepositRequest`
*Note*: The container is new in EIP6110.
```python
class DepositRequest(Container):
pubkey: BLSPubkey
withdrawal_credentials: Bytes32
amount: Gwei
signature: BLSSignature
index: uint64
```
#### `WithdrawalRequest`
*Note*: The container is new in EIP7251:EIP7002.
```python
class WithdrawalRequest(Container):
source_address: ExecutionAddress
validator_pubkey: BLSPubkey
amount: Gwei
```
#### `ConsolidationRequest`
*Note*: The container is new in EIP7251.
```python
class ConsolidationRequest(Container):
source_address: ExecutionAddress
source_pubkey: BLSPubkey
target_pubkey: BLSPubkey
```
#### `ExecutionRequests`
*Note*: This container holds requests from the execution layer that are received in [
`ExecutionPayloadV4`](https://github.com/ethereum/execution-apis/blob/main/src/engine/prague.md#executionpayloadv4) via
the Engine API. These requests are required for CL state transition (see `BeaconBlockBody`).
```python
class ExecutionRequests(Container):
deposits: List[DepositRequest, MAX_DEPOSIT_REQUESTS_PER_PAYLOAD] # [New in Electra:EIP6110]
withdrawals: List[WithdrawalRequest, MAX_WITHDRAWAL_REQUESTS_PER_PAYLOAD] # [New in Electra:EIP7002:EIP7251]
consolidations: List[ConsolidationRequest, MAX_CONSOLIDATION_REQUESTS_PER_PAYLOAD] # [New in Electra:EIP7251]
```
#### `SingleAttestation`
```python
class SingleAttestation(Container):
committee_index: CommitteeIndex
attester_index: ValidatorIndex
data: AttestationData
signature: BLSSignature
```
### Modified Containers
#### `AttesterSlashing`
```python
class AttesterSlashing(Container):
attestation_1: IndexedAttestation # [Modified in Electra:EIP7549]
attestation_2: IndexedAttestation # [Modified in Electra:EIP7549]
```
#### `BeaconBlockBody`
```python
class BeaconBlockBody(Container):
randao_reveal: BLSSignature
eth1_data: Eth1Data # Eth1 data vote
graffiti: Bytes32 # Arbitrary data
# Operations
proposer_slashings: List[ProposerSlashing, MAX_PROPOSER_SLASHINGS]
attester_slashings: List[AttesterSlashing, MAX_ATTESTER_SLASHINGS_ELECTRA] # [Modified in Electra:EIP7549]
attestations: List[Attestation, MAX_ATTESTATIONS_ELECTRA] # [Modified in Electra:EIP7549]
deposits: List[Deposit, MAX_DEPOSITS]
voluntary_exits: List[SignedVoluntaryExit, MAX_VOLUNTARY_EXITS]
sync_aggregate: SyncAggregate
# Execution
execution_payload: ExecutionPayload
bls_to_execution_changes: List[SignedBLSToExecutionChange, MAX_BLS_TO_EXECUTION_CHANGES]
blob_kzg_commitments: List[KZGCommitment, MAX_BLOB_COMMITMENTS_PER_BLOCK]
execution_requests: ExecutionRequests # [New in Electra]
```
### Extended Containers
#### `Attestation`
```python
class Attestation(Container):
aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE * MAX_COMMITTEES_PER_SLOT] # [Modified in Electra:EIP7549]
data: AttestationData
signature: BLSSignature
committee_bits: Bitvector[MAX_COMMITTEES_PER_SLOT] # [New in Electra:EIP7549]
```
#### `IndexedAttestation`
```python
class IndexedAttestation(Container):
# [Modified in Electra:EIP7549]
attesting_indices: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE * MAX_COMMITTEES_PER_SLOT]
data: AttestationData
signature: BLSSignature
```
#### `BeaconState`
```python
class BeaconState(Container):
# Versioning
genesis_time: uint64
genesis_validators_root: Root
slot: Slot
fork: Fork
# History
latest_block_header: BeaconBlockHeader
block_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT]
state_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT]
historical_roots: List[Root, HISTORICAL_ROOTS_LIMIT]
# Eth1
eth1_data: Eth1Data
eth1_data_votes: List[Eth1Data, EPOCHS_PER_ETH1_VOTING_PERIOD * SLOTS_PER_EPOCH]
eth1_deposit_index: uint64
# Registry
validators: List[Validator, VALIDATOR_REGISTRY_LIMIT]
balances: List[Gwei, VALIDATOR_REGISTRY_LIMIT]
# Randomness
randao_mixes: Vector[Bytes32, EPOCHS_PER_HISTORICAL_VECTOR]
# Slashings
slashings: Vector[Gwei, EPOCHS_PER_SLASHINGS_VECTOR] # Per-epoch sums of slashed effective balances
# Participation
previous_epoch_participation: List[ParticipationFlags, VALIDATOR_REGISTRY_LIMIT]
current_epoch_participation: List[ParticipationFlags, VALIDATOR_REGISTRY_LIMIT]
# Finality
justification_bits: Bitvector[JUSTIFICATION_BITS_LENGTH] # Bit set for every recent justified epoch
previous_justified_checkpoint: Checkpoint
current_justified_checkpoint: Checkpoint
finalized_checkpoint: Checkpoint
# Inactivity
inactivity_scores: List[uint64, VALIDATOR_REGISTRY_LIMIT]
# Sync
current_sync_committee: SyncCommittee
next_sync_committee: SyncCommittee
# Execution
latest_execution_payload_header: ExecutionPayloadHeader
# Withdrawals
next_withdrawal_index: WithdrawalIndex
next_withdrawal_validator_index: ValidatorIndex
# Deep history valid from Capella onwards
historical_summaries: List[HistoricalSummary, HISTORICAL_ROOTS_LIMIT]
deposit_requests_start_index: uint64 # [New in Electra:EIP6110]
deposit_balance_to_consume: Gwei # [New in Electra:EIP7251]
exit_balance_to_consume: Gwei # [New in Electra:EIP7251]
earliest_exit_epoch: Epoch # [New in Electra:EIP7251]
consolidation_balance_to_consume: Gwei # [New in Electra:EIP7251]
earliest_consolidation_epoch: Epoch # [New in Electra:EIP7251]
pending_deposits: List[PendingDeposit, PENDING_DEPOSITS_LIMIT] # [New in Electra:EIP7251]
# [New in Electra:EIP7251]
pending_partial_withdrawals: List[PendingPartialWithdrawal, PENDING_PARTIAL_WITHDRAWALS_LIMIT]
pending_consolidations: List[PendingConsolidation, PENDING_CONSOLIDATIONS_LIMIT] # [New in Electra:EIP7251]
```
## Helper functions
### Predicates
#### Modified `compute_proposer_index`
*Note*: The function `compute_proposer_index` is modified to use `MAX_EFFECTIVE_BALANCE_ELECTRA`.
```python
def compute_proposer_index(state: BeaconState, indices: Sequence[ValidatorIndex], seed: Bytes32) -> ValidatorIndex:
"""
Return from ``indices`` a random index sampled by effective balance.
"""
assert len(indices) > 0
MAX_RANDOM_BYTE = 2**8 - 1
i = uint64(0)
total = uint64(len(indices))
while True:
candidate_index = indices[compute_shuffled_index(i % total, total, seed)]
random_byte = hash(seed + uint_to_bytes(uint64(i // 32)))[i % 32]
effective_balance = state.validators[candidate_index].effective_balance
# [Modified in Electra:EIP7251]
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_byte:
return candidate_index
i += 1
```
#### Modified `is_eligible_for_activation_queue`
*Note*: The function `is_eligible_for_activation_queue` is modified to use `MIN_ACTIVATION_BALANCE` instead of `MAX_EFFECTIVE_BALANCE`.
```python
def is_eligible_for_activation_queue(validator: Validator) -> bool:
"""
Check if ``validator`` is eligible to be placed into the activation queue.
"""
return (
validator.activation_eligibility_epoch == FAR_FUTURE_EPOCH
and validator.effective_balance >= MIN_ACTIVATION_BALANCE # [Modified in Electra:EIP7251]
)
```
#### New `is_compounding_withdrawal_credential`
```python
def is_compounding_withdrawal_credential(withdrawal_credentials: Bytes32) -> bool:
return withdrawal_credentials[:1] == COMPOUNDING_WITHDRAWAL_PREFIX
```
#### New `has_compounding_withdrawal_credential`
```python
def has_compounding_withdrawal_credential(validator: Validator) -> bool:
"""
Check if ``validator`` has an 0x02 prefixed "compounding" withdrawal credential.
"""
return is_compounding_withdrawal_credential(validator.withdrawal_credentials)
```
#### New `has_execution_withdrawal_credential`
```python
def has_execution_withdrawal_credential(validator: Validator) -> bool:
"""
Check if ``validator`` has a 0x01 or 0x02 prefixed withdrawal credential.
"""
return has_compounding_withdrawal_credential(validator) or has_eth1_withdrawal_credential(validator)
```
#### Modified `is_fully_withdrawable_validator`
*Note*: The function `is_fully_withdrawable_validator` is modified to use `has_execution_withdrawal_credential` instead of `has_eth1_withdrawal_credential`.
```python
def is_fully_withdrawable_validator(validator: Validator, balance: Gwei, epoch: Epoch) -> bool:
"""
Check if ``validator`` is fully withdrawable.
"""
return (
has_execution_withdrawal_credential(validator) # [Modified in Electra:EIP7251]
and validator.withdrawable_epoch <= epoch
and balance > 0
)
```
#### Modified `is_partially_withdrawable_validator`
*Note*: The function `is_partially_withdrawable_validator` is modified to use `get_max_effective_balance` instead of `MAX_EFFECTIVE_BALANCE` and `has_execution_withdrawal_credential` instead of `has_eth1_withdrawal_credential`.
```python
def is_partially_withdrawable_validator(validator: Validator, balance: Gwei) -> bool:
"""
Check if ``validator`` is partially withdrawable.
"""
max_effective_balance = get_max_effective_balance(validator)
has_max_effective_balance = validator.effective_balance == max_effective_balance # [Modified in Electra:EIP7251]
has_excess_balance = balance > max_effective_balance # [Modified in Electra:EIP7251]
return (
has_execution_withdrawal_credential(validator) # [Modified in Electra:EIP7251]
and has_max_effective_balance
and has_excess_balance
)
```
### Misc
#### New `get_committee_indices`
```python
def get_committee_indices(committee_bits: Bitvector) -> Sequence[CommitteeIndex]:
return [CommitteeIndex(index) for index, bit in enumerate(committee_bits) if bit]
```
#### New `get_max_effective_balance`
```python
def get_max_effective_balance(validator: Validator) -> Gwei:
"""
Get max effective balance for ``validator``.
"""
if has_compounding_withdrawal_credential(validator):
return MAX_EFFECTIVE_BALANCE_ELECTRA
else:
return MIN_ACTIVATION_BALANCE
```
### Beacon state accessors
#### New `get_balance_churn_limit`
```python
def get_balance_churn_limit(state: BeaconState) -> Gwei:
"""
Return the churn limit for the current epoch.
"""
churn = max(
MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA,
get_total_active_balance(state) // CHURN_LIMIT_QUOTIENT
)
return churn - churn % EFFECTIVE_BALANCE_INCREMENT
```
#### New `get_activation_exit_churn_limit`
```python
def get_activation_exit_churn_limit(state: BeaconState) -> Gwei:
"""
Return the churn limit for the current epoch dedicated to activations and exits.
"""
return min(MAX_PER_EPOCH_ACTIVATION_EXIT_CHURN_LIMIT, get_balance_churn_limit(state))
```
#### New `get_consolidation_churn_limit`
```python
def get_consolidation_churn_limit(state: BeaconState) -> Gwei:
return get_balance_churn_limit(state) - get_activation_exit_churn_limit(state)
```
#### New `get_pending_balance_to_withdraw`
```python
def get_pending_balance_to_withdraw(state: BeaconState, validator_index: ValidatorIndex) -> Gwei:
return sum(
withdrawal.amount for withdrawal in state.pending_partial_withdrawals if withdrawal.index == validator_index
)
```
#### Modified `get_attesting_indices`
*Note*: The function `get_attesting_indices` is modified to support EIP7549.
```python
def get_attesting_indices(state: BeaconState, attestation: Attestation) -> Set[ValidatorIndex]:
"""
Return the set of attesting indices corresponding to ``aggregation_bits`` and ``committee_bits``.
"""
output: Set[ValidatorIndex] = set()
committee_indices = get_committee_indices(attestation.committee_bits)
committee_offset = 0
for committee_index in committee_indices:
committee = get_beacon_committee(state, attestation.data.slot, committee_index)
committee_attesters = set(
attester_index for i, attester_index in enumerate(committee)
if attestation.aggregation_bits[committee_offset + i]
)
output = output.union(committee_attesters)
committee_offset += len(committee)
return output
```
#### Modified `get_next_sync_committee_indices`
*Note*: The function `get_next_sync_committee_indices` is modified to use `MAX_EFFECTIVE_BALANCE_ELECTRA`.
```python
def get_next_sync_committee_indices(state: BeaconState) -> Sequence[ValidatorIndex]:
"""
Return the sync committee indices, with possible duplicates, for the next sync committee.
"""
epoch = Epoch(get_current_epoch(state) + 1)
MAX_RANDOM_BYTE = 2**8 - 1
active_validator_indices = get_active_validator_indices(state, epoch)
active_validator_count = uint64(len(active_validator_indices))
seed = get_seed(state, epoch, DOMAIN_SYNC_COMMITTEE)
i = 0
sync_committee_indices: List[ValidatorIndex] = []
while len(sync_committee_indices) < SYNC_COMMITTEE_SIZE:
shuffled_index = compute_shuffled_index(uint64(i % active_validator_count), active_validator_count, seed)
candidate_index = active_validator_indices[shuffled_index]
random_byte = hash(seed + uint_to_bytes(uint64(i // 32)))[i % 32]
effective_balance = state.validators[candidate_index].effective_balance
# [Modified in Electra:EIP7251]
if effective_balance * MAX_RANDOM_BYTE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_byte:
sync_committee_indices.append(candidate_index)
i += 1
return sync_committee_indices
```
### Beacon state mutators
#### Modified `initiate_validator_exit`
*Note*: The function `initiate_validator_exit` is modified to use the new `compute_exit_epoch_and_update_churn` function.
```python
def initiate_validator_exit(state: BeaconState, index: ValidatorIndex) -> None:
"""
Initiate the exit of the validator with index ``index``.
"""
# Return if validator already initiated exit
validator = state.validators[index]
if validator.exit_epoch != FAR_FUTURE_EPOCH:
return
# Compute exit queue epoch [Modified in Electra:EIP7251]
exit_queue_epoch = compute_exit_epoch_and_update_churn(state, validator.effective_balance)
# Set validator exit epoch and withdrawable epoch
validator.exit_epoch = exit_queue_epoch
validator.withdrawable_epoch = Epoch(validator.exit_epoch + MIN_VALIDATOR_WITHDRAWABILITY_DELAY)
```
#### New `switch_to_compounding_validator`
```python
def switch_to_compounding_validator(state: BeaconState, index: ValidatorIndex) -> None:
validator = state.validators[index]
validator.withdrawal_credentials = COMPOUNDING_WITHDRAWAL_PREFIX + validator.withdrawal_credentials[1:]
queue_excess_active_balance(state, index)
```
#### New `queue_excess_active_balance`
```python
def queue_excess_active_balance(state: BeaconState, index: ValidatorIndex) -> None:
balance = state.balances[index]
if balance > MIN_ACTIVATION_BALANCE:
excess_balance = balance - MIN_ACTIVATION_BALANCE
state.balances[index] = MIN_ACTIVATION_BALANCE
validator = state.validators[index]
# Use bls.G2_POINT_AT_INFINITY as a signature field placeholder
# and GENESIS_SLOT to distinguish from a pending deposit request
state.pending_deposits.append(PendingDeposit(
pubkey=validator.pubkey,
withdrawal_credentials=validator.withdrawal_credentials,
amount=excess_balance,
signature=bls.G2_POINT_AT_INFINITY,
slot=GENESIS_SLOT,
))
```
#### New `compute_exit_epoch_and_update_churn`
```python
def compute_exit_epoch_and_update_churn(state: BeaconState, exit_balance: Gwei) -> Epoch:
earliest_exit_epoch = max(state.earliest_exit_epoch, compute_activation_exit_epoch(get_current_epoch(state)))
per_epoch_churn = get_activation_exit_churn_limit(state)
# New epoch for exits.
if state.earliest_exit_epoch < earliest_exit_epoch:
exit_balance_to_consume = per_epoch_churn
else:
exit_balance_to_consume = state.exit_balance_to_consume
# Exit doesn't fit in the current earliest epoch.
if exit_balance > exit_balance_to_consume:
balance_to_process = exit_balance - exit_balance_to_consume
additional_epochs = (balance_to_process - 1) // per_epoch_churn + 1
earliest_exit_epoch += additional_epochs
exit_balance_to_consume += additional_epochs * per_epoch_churn
# Consume the balance and update state variables.
state.exit_balance_to_consume = exit_balance_to_consume - exit_balance
state.earliest_exit_epoch = earliest_exit_epoch
return state.earliest_exit_epoch
```
#### New `compute_consolidation_epoch_and_update_churn`
```python
def compute_consolidation_epoch_and_update_churn(state: BeaconState, consolidation_balance: Gwei) -> Epoch:
earliest_consolidation_epoch = max(
state.earliest_consolidation_epoch, compute_activation_exit_epoch(get_current_epoch(state)))
per_epoch_consolidation_churn = get_consolidation_churn_limit(state)
# New epoch for consolidations.
if state.earliest_consolidation_epoch < earliest_consolidation_epoch:
consolidation_balance_to_consume = per_epoch_consolidation_churn
else:
consolidation_balance_to_consume = state.consolidation_balance_to_consume
# Consolidation doesn't fit in the current earliest epoch.
if consolidation_balance > consolidation_balance_to_consume:
balance_to_process = consolidation_balance - consolidation_balance_to_consume
additional_epochs = (balance_to_process - 1) // per_epoch_consolidation_churn + 1
earliest_consolidation_epoch += additional_epochs
consolidation_balance_to_consume += additional_epochs * per_epoch_consolidation_churn
# Consume the balance and update state variables.
state.consolidation_balance_to_consume = consolidation_balance_to_consume - consolidation_balance
state.earliest_consolidation_epoch = earliest_consolidation_epoch
return state.earliest_consolidation_epoch
```
#### Modified `slash_validator`
*Note*: The function `slash_validator` is modified to change how the slashing penalty and proposer/whistleblower rewards are calculated in accordance with EIP7251.
```python
def slash_validator(state: BeaconState,
slashed_index: ValidatorIndex,
whistleblower_index: ValidatorIndex=None) -> None:
"""
Slash the validator with index ``slashed_index``.
"""
epoch = get_current_epoch(state)
initiate_validator_exit(state, slashed_index)
validator = state.validators[slashed_index]
validator.slashed = True
validator.withdrawable_epoch = max(validator.withdrawable_epoch, Epoch(epoch + EPOCHS_PER_SLASHINGS_VECTOR))
state.slashings[epoch % EPOCHS_PER_SLASHINGS_VECTOR] += validator.effective_balance
# [Modified in Electra:EIP7251]
slashing_penalty = validator.effective_balance // MIN_SLASHING_PENALTY_QUOTIENT_ELECTRA
decrease_balance(state, slashed_index, slashing_penalty)
# Apply proposer and whistleblower rewards
proposer_index = get_beacon_proposer_index(state)
if whistleblower_index is None:
whistleblower_index = proposer_index
whistleblower_reward = Gwei(
validator.effective_balance // WHISTLEBLOWER_REWARD_QUOTIENT_ELECTRA) # [Modified in Electra:EIP7251]
proposer_reward = Gwei(whistleblower_reward * PROPOSER_WEIGHT // WEIGHT_DENOMINATOR)
increase_balance(state, proposer_index, proposer_reward)
increase_balance(state, whistleblower_index, Gwei(whistleblower_reward - proposer_reward))
```
## Beacon chain state transition function
### Epoch processing
#### Modified `process_epoch`
*Note*: The function `process_epoch` is modified to call updated functions and to process pending balance deposits and pending consolidations which are new in Electra.
```python
def process_epoch(state: BeaconState) -> None:
process_justification_and_finalization(state)
process_inactivity_updates(state)
process_rewards_and_penalties(state)
process_registry_updates(state) # [Modified in Electra:EIP7251]
process_slashings(state) # [Modified in Electra:EIP7251]
process_eth1_data_reset(state)
process_pending_deposits(state) # [New in Electra:EIP7251]
process_pending_consolidations(state) # [New in Electra:EIP7251]
process_effective_balance_updates(state) # [Modified in Electra: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)
```
#### Modified `process_registry_updates`
*Note*: The function `process_registry_updates` is modified to
use the updated definitions of `initiate_validator_exit` and `is_eligible_for_activation_queue`
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): # [Modified in Electra:EIP7251]
validator.activation_eligibility_epoch = get_current_epoch(state) + 1
if (
is_active_validator(validator, get_current_epoch(state))
and validator.effective_balance <= EJECTION_BALANCE
):
initiate_validator_exit(state, ValidatorIndex(index)) # [Modified in Electra:EIP7251]
# Activate all eligible validators
# [Modified in Electra:EIP7251]
activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
for validator in state.validators:
if is_eligible_for_activation(state, validator):
validator.activation_epoch = activation_epoch
```
#### Modified `process_slashings`
*Note*: The function `process_slashings` is modified to use a new algorithm to compute correlation penalty.
```python
def process_slashings(state: BeaconState) -> None:
epoch = get_current_epoch(state)
total_balance = get_total_active_balance(state)
adjusted_total_slashing_balance = min(
sum(state.slashings) * PROPORTIONAL_SLASHING_MULTIPLIER_BELLATRIX,
total_balance
)
increment = EFFECTIVE_BALANCE_INCREMENT # Factored out from total balance to avoid uint64 overflow
penalty_per_effective_balance_increment = adjusted_total_slashing_balance // (total_balance // increment)
for index, validator in enumerate(state.validators):
if validator.slashed and epoch + EPOCHS_PER_SLASHINGS_VECTOR // 2 == validator.withdrawable_epoch:
effective_balance_increments = validator.effective_balance // increment
# [Modified in Electra:EIP7251]
penalty = penalty_per_effective_balance_increment * effective_balance_increments
decrease_balance(state, ValidatorIndex(index), penalty)
```
#### New `apply_pending_deposit`
```python
def apply_pending_deposit(state: BeaconState, deposit: PendingDeposit) -> None:
"""
Applies ``deposit`` to the ``state``.
"""
validator_pubkeys = [v.pubkey for v in state.validators]
if deposit.pubkey not in validator_pubkeys:
# Verify the deposit signature (proof of possession) which is not checked by the deposit contract
if is_valid_deposit_signature(
deposit.pubkey,
deposit.withdrawal_credentials,
deposit.amount,
deposit.signature
):
add_validator_to_registry(state, deposit.pubkey, deposit.withdrawal_credentials, deposit.amount)
else:
validator_index = ValidatorIndex(validator_pubkeys.index(deposit.pubkey))
increase_balance(state, validator_index, deposit.amount)
```
#### New `process_pending_deposits`
Iterating over `pending_deposits` queue this function runs the following checks before applying pending deposit:
1. All Eth1 bridge deposits are processed before the first deposit request gets processed.
2. Deposit position in the queue is finalized.
3. Deposit does not exceed the `MAX_PENDING_DEPOSITS_PER_EPOCH` limit.
4. Deposit does not exceed the activation churn limit.
```python
def process_pending_deposits(state: BeaconState) -> None:
next_epoch = Epoch(get_current_epoch(state) + 1)
available_for_processing = state.deposit_balance_to_consume + get_activation_exit_churn_limit(state)
processed_amount = 0
next_deposit_index = 0
deposits_to_postpone = []
is_churn_limit_reached = False
finalized_slot = compute_start_slot_at_epoch(state.finalized_checkpoint.epoch)
for deposit in state.pending_deposits:
# Do not process deposit requests if Eth1 bridge deposits are not yet applied.
if (
# Is deposit request
deposit.slot > GENESIS_SLOT and
# There are pending Eth1 bridge deposits
state.eth1_deposit_index < state.deposit_requests_start_index
):
break
# Check if deposit has been finalized, otherwise, stop processing.
if deposit.slot > finalized_slot:
break
# Check if number of processed deposits has not reached the limit, otherwise, stop processing.
if next_deposit_index >= MAX_PENDING_DEPOSITS_PER_EPOCH:
break
# Read validator state
is_validator_exited = False
is_validator_withdrawn = False
validator_pubkeys = [v.pubkey for v in state.validators]
if deposit.pubkey in validator_pubkeys:
validator = state.validators[ValidatorIndex(validator_pubkeys.index(deposit.pubkey))]
is_validator_exited = validator.exit_epoch < FAR_FUTURE_EPOCH
is_validator_withdrawn = validator.withdrawable_epoch < next_epoch
if is_validator_withdrawn:
# Deposited balance will never become active. Increase balance but do not consume churn
apply_pending_deposit(state, deposit)
elif is_validator_exited:
# Validator is exiting, postpone the deposit until after withdrawable epoch
deposits_to_postpone.append(deposit)
else:
# Check if deposit fits in the churn, otherwise, do no more deposit processing in this epoch.
is_churn_limit_reached = processed_amount + deposit.amount > available_for_processing
if is_churn_limit_reached:
break
# Consume churn and apply deposit.
processed_amount += deposit.amount
apply_pending_deposit(state, deposit)
# Regardless of how the deposit was handled, we move on in the queue.
next_deposit_index += 1
state.pending_deposits = state.pending_deposits[next_deposit_index:] + deposits_to_postpone
# Accumulate churn only if the churn limit has been hit.
if is_churn_limit_reached:
state.deposit_balance_to_consume = available_for_processing - processed_amount
else:
state.deposit_balance_to_consume = Gwei(0)
```
#### New `process_pending_consolidations`
```python
def process_pending_consolidations(state: BeaconState) -> None:
next_epoch = Epoch(get_current_epoch(state) + 1)
next_pending_consolidation = 0
for pending_consolidation in state.pending_consolidations:
source_validator = state.validators[pending_consolidation.source_index]
if source_validator.slashed:
next_pending_consolidation += 1
continue
if source_validator.withdrawable_epoch > next_epoch:
break
# Calculate the consolidated balance
max_effective_balance = get_max_effective_balance(source_validator)
source_effective_balance = min(state.balances[pending_consolidation.source_index], max_effective_balance)
# Move active balance to target. Excess balance is withdrawable.
decrease_balance(state, pending_consolidation.source_index, source_effective_balance)
increase_balance(state, pending_consolidation.target_index, source_effective_balance)
next_pending_consolidation += 1
state.pending_consolidations = state.pending_consolidations[next_pending_consolidation:]
```
#### Modified `process_effective_balance_updates`
*Note*: The function `process_effective_balance_updates` is modified to use the new limit for the maximum effective balance.
```python
def process_effective_balance_updates(state: BeaconState) -> None:
# Update effective balances with hysteresis
for index, validator in enumerate(state.validators):
balance = state.balances[index]
HYSTERESIS_INCREMENT = uint64(EFFECTIVE_BALANCE_INCREMENT // HYSTERESIS_QUOTIENT)
DOWNWARD_THRESHOLD = HYSTERESIS_INCREMENT * HYSTERESIS_DOWNWARD_MULTIPLIER
UPWARD_THRESHOLD = HYSTERESIS_INCREMENT * HYSTERESIS_UPWARD_MULTIPLIER
# [Modified in Electra:EIP7251]
max_effective_balance = get_max_effective_balance(validator)
if (
balance + DOWNWARD_THRESHOLD < validator.effective_balance
or validator.effective_balance + UPWARD_THRESHOLD < balance
):
validator.effective_balance = min(balance - balance % EFFECTIVE_BALANCE_INCREMENT, max_effective_balance)