# EIP7251 - Spec ## Table of contents - [Introduction](#introduction) - [Constants](#constants) - [Withdrawal prefixes](#withdrawal-prefixes) - [Domains](#domains) - [Presets](#presets) - [Gwei values](#gwei-values) - [Rewards and penalties](#rewards-and-penalties) - [Max operations per block](#max-operations-per-block) - [State list lengths](#state-list-lengths) - [Configuration](#configuration) - [Validator cycle](#validator-cycle) - [Containers](#containers) - [New containers](#new-containers) - [New `PendingBalanceDeposit`](#new-pendingbalancedeposit) - [New `PartialWithdrawal`](#new-partialwithdrawal) - [New `ExecutionLayerWithdrawRequest`](#new-executionlayerwithdrawrequest) - [New `Consolidation`](#new-consolidation) - [New `SignedConsolidation`](#new-signedconsolidation) - [New `PendingConsolidation`](#new-pendingconsolidation) - [Extended Containers](#extended-containers) - [`BeaconState`](#beaconstate) - [`BeaconBlockBody`](#beaconblockbody) - [Helpers](#helpers) - [Predicates](#predicates) - [Updated `is_eligible_for_activation_queue`](#updated-is_eligible_for_activation_queue) - [New `has_compounding_withdrawal_credential`](#new-has_compounding_withdrawal_credential) - [New `has_execution_withdrawal_credential`](#new-has_execution_withdrawal_credential) - [Updated `is_fully_withdrawable_validator`](#updated-is_fully_withdrawable_validator) - [Updated `is_partially_withdrawable_validator`](#updated-is_partially_withdrawable_validator) - [Beacon state accessors](#beacon-state-accessors) - [New `get_validator_excess_balance`](#new-get_validator_excess_balance) - [New `get_churn_limit`](#new-get_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_active_balance`](#new-get_active_balance) - [Beacon state mutators](#beacon-state-mutators) - [Updated `initiate_validator_exit`](#updated--initiate_validator_exit) - [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) - [Updated `slash_validator`](#updated-slash_validator) - [Beacon chain state transition function](#beacon-chain-state-transition-function) - [Epoch processing](#epoch-processing) - [Updated `process_epoch`](#updated-process_epoch) - [Updated `process_registry_updates`](#updated--process_registry_updates) - [New `process_pending_balance_deposits`](#new-process_pending_balance_deposits) - [New `process_pending_consolidations`](#new-process_pending_consolidations) - [Updated `process_effective_balance_updates`](#updated-process_effective_balance_updates) - [Block processing](#block-processing) - [Updated `get_expected_withdrawals`](#updated-get_expected_withdrawals) - [Updated `process_withdrawals`](#updated-process_withdrawals) - [Operations](#operations) - [Updated `process_operations`](#updated-process_operations) - [Deposits](#deposits) - [Updated `apply_deposit`](#updated--apply_deposit) - [Modified `add_validator_to_registry`](#modified-add_validator_to_registry) - [Updated `get_validator_from_deposit`](#updated-get_validator_from_deposit) - [Withdrawals](#withdrawals) - [New `process_execution_layer_withdraw_request`](#new-process_execution_layer_withdraw_request) - [Consolidations](#consolidations) - [New `process_consolidation`](#new-process_consolidation) ## 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 [security considerations](https://notes.ethereum.org/@fradamt/meb-increase-security). *Note:* This specification is built upon [Deneb](../../deneb/beacon-chain.md). ## Constants The following values are (non-configurable) constants used throughout the specification. ### 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` | `Gwei(2**16)` (= 65,536) | ### Max operations per block | Name | Value | | - | - | | `MAX_CONSOLIDATIONS` | `uint64(1)` | ### 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) | # 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 #### New `PendingBalanceDeposit` ```python class PendingBalanceDeposit(Container): index: ValidatorIndex amount: Gwei ``` #### New `PartialWithdrawal` ```python class PartialWithdrawal(Container): index: ValidatorIndex amount: Gwei withdrawable_epoch: Epoch ``` #### New `ExecutionLayerWithdrawRequest` ```python class ExecutionLayerWithdrawRequest(Container): source_address: ExecutionAddress validator_pubkey: BLSPubkey amount: Gwei ``` #### New `Consolidation` ```python class Consolidation(Container): source_index: ValidatorIndex target_index: ValidatorIndex epoch: Epoch ``` #### New `SignedConsolidation` ```python class SignedConsolidation(Container): message: Consolidation signature: BLSSignature ``` #### New `PendingConsolidation` ```python class PendingConsolidation(Container): source_index: ValidatorIndex target_index: ValidatorIndex ``` ### Extended Containers #### `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] # 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[PartialWithdrawal, PENDING_PARTIAL_WITHDRAWALS_LIMIT] # [New in EIP-7251] pending_consolidations: List[PendingConsolidation, PENDING_CONSOLIDATIONS_LIMIT] # [New in EIP-7251] ``` #### `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] 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] ``` ## Helpers ### Predicates #### Updated `is_eligible_for_activation_queue` ```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 EIP7251] ) ``` #### 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 validator.withdrawal_credentials[:1] == COMPOUNDING_WITHDRAWAL_PREFIX ``` #### 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) ``` #### Updated `is_fully_withdrawable_validator` ```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 EIP7251] and validator.withdrawable_epoch <= epoch and balance > 0 ) ``` #### Updated `is_partially_withdrawable_validator` ```python def is_partially_withdrawable_validator(validator: Validator, balance: Gwei) -> bool: """ Check if ``validator`` is partially withdrawable. """ return ( has_execution_withdrawal_credential(validator) # [Modified in EIP7251] and get_validator_excess_balance(validator, balance) > 0 ) ``` ### Beacon state accessors #### New `get_validator_excess_balance` ```python def get_validator_excess_balance(validator: Validator, balance: Gwei) -> Gwei: """ Get excess balance for partial withdrawals for ``validator``. """ if has_compounding_withdrawal_credential(validator) and balance > MAX_EFFECTIVE_BALANCE_EIP7251: return balance - MAX_EFFECTIVE_BALANCE_EIP7251 elif has_eth1_withdrawal_credential(validator) and balance > MIN_ACTIVATION_BALANCE: return balance - MIN_ACTIVATION_BALANCE return Gwei(0) ``` #### New `get_churn_limit` ```python 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` ```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_churn_limit(state)) ``` #### New `get_consolidation_churn_limit` ```python def get_consolidation_churn_limit(state: BeaconState) -> Gwei: return get_churn_limit(state) - get_activation_exit_churn_limit(state) ``` #### New `get_active_balance` ```python def get_active_balance(state: BeaconState, validator_index: ValidatorIndex) -> Gwei: active_balance_ceil = ( MIN_ACTIVATION_BALANCE if has_eth1_withdrawal_credential(state.validators[validator_index]) else MAX_EFFECTIVE_BALANCE_EIP7251 ) return min(state.balances[validator_index], active_balance_ceil) ``` ### Beacon state mutators #### Updated `initiate_validator_exit` ```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 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 `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)) 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` ```python 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` ```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 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) 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` ```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 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) ``` #### Updated `process_registry_updates` ```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 ): 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` ```python 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 = 0 else: state.deposit_balance_to_consume = available_for_processing - processed_amount ``` #### New `process_pending_consolidations` ```python 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 next_pending_consolidation += 1 # Move active balance to target. Excess balance is withdrawable. active_balance = get_active_balance(state, pending_consolidation.source_index) state.balances[pending_consolidation.source_index] -= active_balance state.balances[pending_consolidation.target_index] += active_balance state.pending_consolidations = state.pending_consolidations[next_pending_consolidation:] ``` #### Updated `process_effective_balance_updates` ```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 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 ```python 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` ```python 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_WITHDRAWALS_PER_PAYLOAD // 2: break validator = state.validators[withdrawal.index] if validator.exit_epoch == FAR_FUTURE_EPOCH and state.balances[withdrawal.index] > MIN_ACTIVATION_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_len = 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=get_validator_excess_balance(validator, balance), # [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_len ``` ##### Updated `process_withdrawals` ```python def process_withdrawals(state: BeaconState, payload: ExecutionPayload) -> None: expected_withdrawals, partial_withdrawals_len = 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_len:] # 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` ```python 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) 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` ```python 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 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) if bls.Verify(pubkey, signing_root, 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, amount)) # [Modified in EIP-7251] ``` #### Modified `add_validator_to_registry` ```python 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, amount) 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, amount)) # [New in EIP7251] ``` ###### Updated `get_validator_from_deposit` ```python 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` ```python 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 == 0 # If partial withdrawal queue is full, only full exits are processed if not (is_full_exit_request or len(state.pending_consolidations) < PENDING_PARTIAL_WITHDRAWALS_LIMIT): 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 # New condition: only allow partial withdrawals with compounding withdrawal credentials if not (is_full_exit_request or has_compounding_withdrawal_credential(validator)): return pending_balance_to_withdraw = sum( item.amount for item in state.pending_partial_withdrawals if item.index == index ) # only exit validator if it has no pending withdrawals in the queue if is_full_exit_request and pending_balance_to_withdraw == 0: initiate_validator_exit(state, index) elif state.balances[index] > MIN_ACTIVATION_BALANCE + pending_balance_to_withdraw: 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(PartialWithdrawal( index=index, amount=to_withdraw, withdrawable_epoch=withdrawable_epoch, )) ``` ##### Consolidations ###### New `process_consolidation` ```python 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[1:] == target_validator.withdrawal_credentials[1:] # 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 active_balance = get_active_balance(state, consolidation.source_index) source_validator.exit_epoch = compute_consolidation_epoch_and_update_churn(state, active_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 )) ```