EIP7251 - Spec
Table of contents
Introduction
See a modest proposal, the diff view and
security considerations.
Note: This specification is built upon Deneb.
Constants
The following values are (non-configurable) constants used throughout the specification.
Misc
| Name |
Value |
FULL_EXIT_REQUEST_AMOUNT |
uint64(0) |
Withdrawal prefixes
| Name |
Value |
BLS_WITHDRAWAL_PREFIX |
Bytes1('0x00') |
ETH1_ADDRESS_WITHDRAWAL_PREFIX |
Bytes1('0x01') |
COMPOUNDING_WITHDRAWAL_PREFIX |
Bytes1('0x02') |
Domains
| Name |
Value |
DOMAIN_CONSOLIDATION |
DomainType('0x0B000000') |
Presets
Gwei values
| Name |
Value |
MIN_ACTIVATION_BALANCE |
Gwei(2**5 * 10**9) (= 32,000,000,000) |
MAX_EFFECTIVE_BALANCE_EIP7251 |
Gwei(2**11 * 10**9) (= 2048,000,000,000) |
Rewards and penalties
| Name |
Value |
MIN_SLASHING_PENALTY_QUOTIENT_EIP7251 |
uint64(2**12) (= 4,096) |
WHISTLEBLOWER_REWARD_QUOTIENT_EIP7251 |
uint64(2**12) (= 4,096) |
Max operations per block
| Name |
Value |
MAX_CONSOLIDATIONS |
uint64(1) |
Execution
| 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
| Name |
Value |
Unit |
PENDING_BALANCE_DEPOSITS_LIMIT |
uint64(2**27) (= 134,217,728) |
pending balance deposits |
PENDING_PARTIAL_WITHDRAWALS_LIMIT |
uint64(2**27) (= 134,217,728) |
pending partial withdrawals |
PENDING_CONSOLIDATIONS_LIMIT |
uint64(2**18) (= 262,144) |
pending consolidations |
Configuration
Validator cycle
| Name |
Value |
MIN_PER_EPOCH_CHURN_LIMIT_EIP7251 |
Gwei(2**7 * 10**9) (= 128,000,000,000) |
MAX_PER_EPOCH_ACTIVATION_EXIT_CHURN_LIMIT |
Gwei(2**8 * 10**9) (256,000,000,000) |
Containers
New containers
New PendingBalanceDeposit
class PendingBalanceDeposit(Container):
index: ValidatorIndex
amount: Gwei
New PendingPartialWithdrawal
class PendingPartialWithdrawal(Container):
index: ValidatorIndex
amount: Gwei
withdrawable_epoch: Epoch
New ExecutionLayerWithdrawRequest
class ExecutionLayerWithdrawRequest(Container):
source_address: ExecutionAddress
validator_pubkey: BLSPubkey
amount: Gwei
New Consolidation
class Consolidation(Container):
source_index: ValidatorIndex
target_index: ValidatorIndex
epoch: Epoch
New SignedConsolidation
class SignedConsolidation(Container):
message: Consolidation
signature: BLSSignature
New PendingConsolidation
class PendingConsolidation(Container):
source_index: ValidatorIndex
target_index: ValidatorIndex
Extended Containers
BeaconState
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]
# EIP-7251
deposit_balance_to_consume: Gwei # [New in EIP-7251]
exit_balance_to_consume: Gwei # [New in EIP-7251]
earliest_exit_epoch: Epoch # [New in EIP-7251]
consolidation_balance_to_consume: Gwei # [New in EIP-7251]
earliest_consolidation_epoch: Epoch # [New in EIP-7251]
pending_balance_deposits: List[PendingBalanceDeposit, PENDING_BALANCE_DEPOSITS_LIMIT] # [New in EIP-7251]
pending_partial_withdrawals: List[PendingPartialWithdrawal, PENDING_PARTIAL_WITHDRAWALS_LIMIT] # [New in EIP-7251]
pending_consolidations: List[PendingConsolidation, PENDING_CONSOLIDATIONS_LIMIT] # [New in EIP-7251]
BeaconBlockBody
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]
attestations: List[Attestation, MAX_ATTESTATIONS]
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]
consolidations: List[SignedConsolidation, MAX_CONSOLIDATIONS] # [New in EIP-7251]
ExecutionPayload
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]
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
Updated is_eligible_for_activation_queue
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 EIP7251]
)
New is_compounding_withdrawal_credential
def is_compounding_withdrawal_credential(withdrawal_credentials: Bytes32) -> bool:
return withdrawal_credentials[:1] == COMPOUNDING_WITHDRAWAL_PREFIX
New has_compounding_withdrawal_credential
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
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)
Updated is_fully_withdrawable_validator
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 EIP7251]
and validator.withdrawable_epoch <= epoch
and balance > 0
)
Updated is_partially_withdrawable_validator
def is_partially_withdrawable_validator(validator: Validator, balance: Gwei) -> bool:
"""
Check if ``validator`` is partially withdrawable.
"""
max_effective_balance = get_validator_max_effective_balance(validator)
has_max_effective_balance = validator.effective_balance == max_effective_balance # [Modified in EIP7251]
has_excess_balance = balance > max_effective_balance # [Modified in EIP7251]
return (
has_execution_withdrawal_credential(validator) # [Modified in EIP7251]
and has_max_effective_balance
and has_excess_balance
)
Beacon state accessors
New get_validator_max_effective_balance
def get_validator_max_effective_balance(validator: Validator) -> Gwei:
"""
Get max effective balance for ``validator``.
"""
if has_compounding_withdrawal_credential(validator):
return MAX_EFFECTIVE_BALANCE_EIP7251
else:
return MIN_ACTIVATION_BALANCE
New get_churn_limit
def get_churn_limit(state: BeaconState) -> Gwei:
"""
Return the churn limit for the current epoch.
"""
churn = max(
MIN_PER_EPOCH_CHURN_LIMIT_EIP7251,
get_total_active_balance(state) // CHURN_LIMIT_QUOTIENT
)
return churn - churn % EFFECTIVE_BALANCE_INCREMENT
New get_activation_exit_churn_limit
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_churn_limit(state))
New get_consolidation_churn_limit
def get_consolidation_churn_limit(state: BeaconState) -> Gwei:
return get_churn_limit(state) - get_activation_exit_churn_limit(state)
New get_active_balance
def get_active_balance(state: BeaconState, validator_index: ValidatorIndex) -> Gwei:
max_effective_balance = get_validator_max_effective_balance(state.validators[validator_index])
return min(state.balances[validator_index], max_effective_balance)
New get_pending_balance_to_withdraw
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)
Beacon state mutators
Updated initiate_validator_exit
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 EIP 7251]
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
def switch_to_compounding_validator(state: BeaconState, index: ValidatorIndex) -> None:
validator = state.validators[index]
if has_eth1_withdrawal_credential(validator):
validator.withdrawal_credentials[:1] = COMPOUNDING_WITHDRAWAL_PREFIX
queue_excess_active_balance(state, index)
New queue_excess_active_balance
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
state.pending_balance_deposits.append(
PendingBalanceDeposit(index=index, amount=excess_balance)
)
New compute_exit_epoch_and_update_churn
def compute_exit_epoch_and_update_churn(state: BeaconState, exit_balance: Gwei) -> Epoch:
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:
state.earliest_exit_epoch = earliest_exit_epoch
state.exit_balance_to_consume = per_epoch_churn
if exit_balance <= state.exit_balance_to_consume:
# Exit fits in the current earliest epoch.
state.exit_balance_to_consume -= exit_balance
else:
# Exit doesn't fit in the current earliest epoch.
balance_to_process = exit_balance - state.exit_balance_to_consume
additional_epochs, remainder = divmod(balance_to_process, per_epoch_churn)
state.earliest_exit_epoch += additional_epochs + 1
state.exit_balance_to_consume = per_epoch_churn - remainder
return state.earliest_exit_epoch
New compute_consolidation_epoch_and_update_churn
def compute_consolidation_epoch_and_update_churn(state: BeaconState, consolidation_balance: Gwei) -> Epoch:
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:
state.earliest_consolidation_epoch = earliest_consolidation_epoch
state.consolidation_balance_to_consume = per_epoch_consolidation_churn
if consolidation_balance <= state.consolidation_balance_to_consume:
# Consolidation fits in the current earliest consolidation epoch.
state.consolidation_balance_to_consume -= consolidation_balance
else:
# Consolidation doesn't fit in the current earliest epoch.
balance_to_process = consolidation_balance - state.consolidation_balance_to_consume
additional_epochs, remainder = divmod(balance_to_process, per_epoch_consolidation_churn)
state.earliest_consolidation_epoch += additional_epochs + 1
state.consolidation_balance_to_consume = per_epoch_consolidation_churn - remainder
return state.earliest_consolidation_epoch
Updated slash_validator
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
slashing_penalty = validator.effective_balance // MIN_SLASHING_PENALTY_QUOTIENT_EIP7251 # [Modified in EIP7251]
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_EIP7251) # [Modified in 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
Updated process_epoch
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 EIP7251]
process_slashings(state)
process_eth1_data_reset(state)
process_pending_balance_deposits(state) # New in EIP7251
process_pending_consolidations(state) # New in EIP7251
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.
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
):
initiate_validator_exit(state, ValidatorIndex(index))
# Activate all eligible validators
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
New process_pending_balance_deposits
def process_pending_balance_deposits(state: BeaconState) -> None:
available_for_processing = state.deposit_balance_to_consume + get_activation_exit_churn_limit(state)
processed_amount = 0
next_deposit_index = 0
for deposit in state.pending_balance_deposits:
if processed_amount + deposit.amount > available_for_processing:
break
increase_balance(state, deposit.index, deposit.amount)
processed_amount += deposit.amount
next_deposit_index += 1
state.pending_balance_deposits = state.pending_balance_deposits[next_deposit_index:]
if len(state.pending_balance_deposits) == 0:
state.deposit_balance_to_consume = Gwei(0)
else:
state.deposit_balance_to_consume = available_for_processing - processed_amount
New process_pending_consolidations
def process_pending_consolidations(state: BeaconState) -> None:
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 > get_current_epoch(state):
break
# Churn any target excess active balance of target and raise its max
switch_to_compounding_validator(state, pending_consolidation.target_index)
# Move active balance to target. Excess balance is withdrawable.
active_balance = get_active_balance(state, pending_consolidation.source_index)
decrease_balance(state, pending_consolidation.source_index, active_balance)
increase_balance(state, pending_consolidation.target_index, active_balance)
next_pending_consolidation += 1
state.pending_consolidations = state.pending_consolidations[next_pending_consolidation:]
Updated process_effective_balance_updates
process_effective_balance_updates is updated with a new limit for the maximum effective balance.
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
EFFECTIVE_BALANCE_LIMIT = (
MAX_EFFECTIVE_BALANCE_EIP7251 if has_compounding_withdrawal_credential(validator)
else MIN_ACTIVATION_BALANCE
)
if (
balance + DOWNWARD_THRESHOLD < validator.effective_balance
or validator.effective_balance + UPWARD_THRESHOLD < balance
):
validator.effective_balance = min(balance - balance % EFFECTIVE_BALANCE_INCREMENT, EFFECTIVE_BALANCE_LIMIT)
Block processing
def process_block(state: BeaconState, block: BeaconBlock) -> None:
process_block_header(state, block)
process_withdrawals(state, block.body.execution_payload) # [Modified in EIP7251]
process_execution_payload(state, block.body, EXECUTION_ENGINE)
process_randao(state, block.body)
process_eth1_data(state, block.body)
process_operations(state, block.body) # [Modified in EIP7251]
process_sync_aggregate(state, block.body.sync_aggregate)
Updated get_expected_withdrawals
def get_expected_withdrawals(state: BeaconState) -> Tuple[Sequence[Withdrawal], uint64]:
epoch = get_current_epoch(state)
withdrawal_index = state.next_withdrawal_index
validator_index = state.next_withdrawal_validator_index
withdrawals: List[Withdrawal] = []
# [New in EIP7251] Consume pending partial withdrawals
for withdrawal in state.pending_partial_withdrawals:
if withdrawal.withdrawable_epoch > epoch or len(withdrawals) == MAX_PARTIAL_WITHDRAWALS_PER_PAYLOAD:
break
validator = state.validators[withdrawal.index]
has_sufficient_effective_balance = validator.effective_balance >= MIN_ACTIVATION_BALANCE
has_excess_balance = state.balances[withdrawal.index] > MIN_ACTIVATION_BALANCE
if validator.exit_epoch == FAR_FUTURE_EPOCH and has_sufficient_effective_balance and has_excess_balance:
withdrawable_balance = min(state.balances[withdrawal.index] - MIN_ACTIVATION_BALANCE, withdrawal.amount)
withdrawals.append(Withdrawal(
index=withdrawal_index,
validator_index=withdrawal.index,
address=ExecutionAddress(validator.withdrawal_credentials[12:]),
amount=withdrawable_balance,
))
withdrawal_index += WithdrawalIndex(1)
partial_withdrawals_count = len(withdrawals)
# END: Consume pending partial withdrawals
# Sweep for remaining.
bound = min(len(state.validators), MAX_VALIDATORS_PER_WITHDRAWALS_SWEEP)
for _ in range(bound):
validator = state.validators[validator_index]
balance = state.balances[validator_index]
if is_fully_withdrawable_validator(validator, balance, epoch):
withdrawals.append(Withdrawal(
index=withdrawal_index,
validator_index=validator_index,
address=ExecutionAddress(validator.withdrawal_credentials[12:]),
amount=balance,
))
withdrawal_index += WithdrawalIndex(1)
elif is_partially_withdrawable_validator(validator, balance):
withdrawals.append(Withdrawal(
index=withdrawal_index,
validator_index=validator_index,
address=ExecutionAddress(validator.withdrawal_credentials[12:]),
amount=balance - get_validator_max_effective_balance(validator), # [Modified in EIP7251]
))
withdrawal_index += WithdrawalIndex(1)
if len(withdrawals) == MAX_WITHDRAWALS_PER_PAYLOAD:
break
validator_index = ValidatorIndex((validator_index + 1) % len(state.validators))
return withdrawals, partial_withdrawals_count
Updated process_withdrawals
def process_withdrawals(state: BeaconState, payload: ExecutionPayload) -> None:
expected_withdrawals, partial_withdrawals_count = get_expected_withdrawals(state) # [Modified in EIP7251]
assert len(payload.withdrawals) == len(expected_withdrawals)
for expected_withdrawal, withdrawal in zip(expected_withdrawals, payload.withdrawals):
assert withdrawal == expected_withdrawal
decrease_balance(state, withdrawal.validator_index, withdrawal.amount)
# [New in EIP7251] update pending partial withdrawals
state.pending_partial_withdrawals = state.pending_partial_withdrawals[partial_withdrawals_count:]
# Update the next withdrawal index if this block contained withdrawals
if len(expected_withdrawals) != 0:
latest_withdrawal = expected_withdrawals[-1]
state.next_withdrawal_index = WithdrawalIndex(latest_withdrawal.index + 1)
# Update the next validator index to start the next withdrawal sweep
if len(expected_withdrawals) == MAX_WITHDRAWALS_PER_PAYLOAD:
# Next sweep starts after the latest withdrawal's validator index
next_validator_index = ValidatorIndex((expected_withdrawals[-1].validator_index + 1) % len(state.validators))
state.next_withdrawal_validator_index = next_validator_index
else:
# Advance sweep by the max length of the sweep if there was not a full set of withdrawals
next_index = state.next_withdrawal_validator_index + MAX_VALIDATORS_PER_WITHDRAWALS_SWEEP
next_validator_index = ValidatorIndex(next_index % len(state.validators))
state.next_withdrawal_validator_index = next_validator_index
Operations
Updated process_operations
def process_operations(state: BeaconState, body: BeaconBlockBody) -> None:
# Verify that outstanding deposits are processed up to the maximum number of deposits
assert len(body.deposits) == min(MAX_DEPOSITS, state.eth1_data.deposit_count - state.eth1_deposit_index)
def for_ops(operations: Sequence[Any], fn: Callable[[BeaconState, Any], None]) -> None:
for operation in operations:
fn(state, operation)
for_ops(body.proposer_slashings, process_proposer_slashing)
for_ops(body.attester_slashings, process_attester_slashing)
for_ops(body.attestations, process_attestation)
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]
Deposits
Updated apply_deposit
NOTE: process_deposit is updated with a new definition of apply_deposit.
def apply_deposit(state: BeaconState,
pubkey: BLSPubkey,
withdrawal_credentials: Bytes32,
amount: uint64,
signature: BLSSignature) -> None:
validator_pubkeys = [v.pubkey for v in state.validators]
if 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(pubkey, withdrawal_credentials, amount, signature):
add_validator_to_registry(state, pubkey, withdrawal_credentials, amount)
else:
# Increase balance by deposit amount
index = ValidatorIndex(validator_pubkeys.index(pubkey))
state.pending_balance_deposits.append(
PendingBalanceDeposit(index=index, amount=amount)) # [Modified in EIP-7251]
# Check if valid deposit switch to compounding credentials
if (
is_compounding_withdrawal_credential(withdrawal_credentials)
and has_eth1_withdrawal_credential(state.validators[index])
and is_valid_deposit_signature(pubkey, withdrawal_credentials, amount, signature)
):
switch_to_compounding_validator(state, index)
New is_valid_deposit_signature
def is_valid_deposit_signature(pubkey: BLSPubkey,
withdrawal_credentials: Bytes32,
amount: uint64,
signature: BLSSignature) -> bool:
deposit_message = DepositMessage(
pubkey=pubkey,
withdrawal_credentials=withdrawal_credentials,
amount=amount,
)
domain = compute_domain(DOMAIN_DEPOSIT) # Fork-agnostic domain since deposits are valid across forks
signing_root = compute_signing_root(deposit_message, domain)
return bls.Verify(pubkey, signing_root, signature)
Modified add_validator_to_registry
def add_validator_to_registry(state: BeaconState,
pubkey: BLSPubkey,
withdrawal_credentials: Bytes32,
amount: uint64) -> None:
index = get_index_for_new_validator(state)
validator = get_validator_from_deposit(pubkey, withdrawal_credentials)
set_or_append_list(state.validators, index, validator)
set_or_append_list(state.balances, index, 0) # [Modified in EIP7251]
set_or_append_list(state.previous_epoch_participation, index, ParticipationFlags(0b0000_0000))
set_or_append_list(state.current_epoch_participation, index, ParticipationFlags(0b0000_0000))
set_or_append_list(state.inactivity_scores, index, uint64(0))
state.pending_balance_deposits.append(PendingBalanceDeposit(index=index, amount=amount)) # [New in EIP7251]
Updated get_validator_from_deposit
def get_validator_from_deposit(pubkey: BLSPubkey, withdrawal_credentials: Bytes32) -> Validator:
return Validator(
pubkey=pubkey,
withdrawal_credentials=withdrawal_credentials,
activation_eligibility_epoch=FAR_FUTURE_EPOCH,
activation_epoch=FAR_FUTURE_EPOCH,
exit_epoch=FAR_FUTURE_EPOCH,
withdrawable_epoch=FAR_FUTURE_EPOCH,
effective_balance=0, # [Modified in EIP7251]
)
Withdrawals
New process_execution_layer_withdraw_request
def process_execution_layer_withdraw_request(
state: BeaconState,
execution_layer_withdraw_request: ExecutionLayerWithdrawRequest
) -> None:
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 len(state.pending_partial_withdrawals) >= PENDING_PARTIAL_WITHDRAWALS_LIMIT and not is_full_exit_request:
return
validator_pubkeys = [v.pubkey for v in state.validators]
index = ValidatorIndex(validator_pubkeys.index(execution_layer_withdraw_request.validator_pubkey))
validator = state.validators[index]
# Same conditions as in EIP-7002
if not (
has_execution_withdrawal_credential(validator)
# Verify withdrawal credentials
and validator.withdrawal_credentials[12:] == execution_layer_withdraw_request.source_address
# Verify the validator is active
and is_active_validator(validator, get_current_epoch(state))
# Verify exit has not been initiated, and slashed
and validator.exit_epoch == FAR_FUTURE_EPOCH
# Verify the validator has been active long enough
and get_current_epoch(state) >= validator.activation_epoch + SHARD_COMMITTEE_PERIOD
):
return
pending_balance_to_withdraw = get_pending_balance_to_withdraw(state, index)
if is_full_exit_request:
# Only exit validator if it has no pending withdrawals in the queue
if pending_balance_to_withdraw == 0:
initiate_validator_exit(state, index)
return
has_sufficient_effective_balance = validator.effective_balance >= MIN_ACTIVATION_BALANCE
has_excess_balance = state.balances[index] > MIN_ACTIVATION_BALANCE + pending_balance_to_withdraw
# Only allow partial withdrawals with compounding withdrawal credentials
if has_compounding_withdrawal_credential(validator) and has_sufficient_effective_balance and has_excess_balance:
to_withdraw = min(
state.balances[index] - MIN_ACTIVATION_BALANCE - pending_balance_to_withdraw,
amount
)
exit_queue_epoch = compute_exit_epoch_and_update_churn(state, to_withdraw)
withdrawable_epoch = Epoch(exit_queue_epoch + MIN_VALIDATOR_WITHDRAWABILITY_DELAY)
state.pending_partial_withdrawals.append(PendingPartialWithdrawal(
index=index,
amount=to_withdraw,
withdrawable_epoch=withdrawable_epoch,
))
Consolidations
New process_consolidation
def process_consolidation(state: BeaconState, signed_consolidation: SignedConsolidation) -> None:
# If the pending consolidations queue is full, no consolidations are allowed in the block
assert len(state.pending_consolidations) < PENDING_CONSOLIDATIONS_LIMIT
# If there is too little available consolidation churn limit, no consolidations are allowed in the block
assert get_consolidation_churn_limit(state) > MIN_ACTIVATION_BALANCE
consolidation = signed_consolidation.message
# Verify that source != target, so a consolidation cannot be used as an exit.
assert consolidation.source_index != consolidation.target_index
source_validator = state.validators[consolidation.source_index]
target_validator = state.validators[consolidation.target_index]
# Verify the source and the target are active
current_epoch = get_current_epoch(state)
assert is_active_validator(source_validator, current_epoch)
assert is_active_validator(target_validator, current_epoch)
# Verify exits for source and target have not been initiated
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
# Verify the source and the target have Execution layer withdrawal credentials
assert has_execution_withdrawal_credential(source_validator)
assert has_execution_withdrawal_credential(target_validator)
# Verify the same withdrawal address
assert source_validator.withdrawal_credentials[12:] == target_validator.withdrawal_credentials[12:]
# Verify consolidation is signed by the source and the target
domain = compute_domain(DOMAIN_CONSOLIDATION, genesis_validators_root=state.genesis_validators_root)
signing_root = compute_signing_root(consolidation, domain)
pubkeys = [source_validator.pubkey, target_validator.pubkey]
assert bls.FastAggregateVerify(pubkeys, signing_root, signed_consolidation.signature)
# Initiate source validator exit and append pending consolidation
source_validator.exit_epoch = compute_consolidation_epoch_and_update_churn(
state, source_validator.effective_balance)
source_validator.withdrawable_epoch = Epoch(
source_validator.exit_epoch + MIN_VALIDATOR_WITHDRAWABILITY_DELAY
)
state.pending_consolidations.append(PendingConsolidation(
source_index=consolidation.source_index,
target_index=consolidation.target_index
))
Voluntary exits
Updated process_voluntary_exit
def process_voluntary_exit(state: BeaconState, signed_voluntary_exit: SignedVoluntaryExit) -> None:
voluntary_exit = signed_voluntary_exit.message
validator = state.validators[voluntary_exit.validator_index]
# Verify the validator is active
assert is_active_validator(validator, get_current_epoch(state))
# Verify exit has not been initiated
assert validator.exit_epoch == FAR_FUTURE_EPOCH
# Exits must specify an epoch when they become valid; they are not valid before then
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 = 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)
# 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.
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