Electra -- The Beacon Chain

Notice: This document is a work-in-progress for researchers and implementers.

Introduction

Electra is a consensus-layer upgrade containing a number of features. Including:

EIP-6110: Supply validator deposits on chain
EIP-7002: Execution layer triggerable exits
EIP-7251: Increase the MAX_EFFECTIVE_BALANCE
EIP-7549: Move committee index outside Attestation

Note: This specification is built upon Deneb 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]
`FULL_EXIT_REQUEST_AMOUNT`	`uint64(0)`	[New in Electra:EIP7002]

Withdrawal prefixes

Name	Value
`COMPOUNDING_WITHDRAWAL_PREFIX`	`Bytes1('0x02')`

Preset

Gwei values

Name	Value
`MIN_ACTIVATION_BALANCE`	`Gwei(2*5 10**9)` (= 32,000,000,000)
`MAX_EFFECTIVE_BALANCE_ELECTRA`	`Gwei(2*11 10**9)` (= 2048,000,000,000)

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 deposit receipts allowed 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(1)` (= 1)	[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

Validator cycle

Name	Value
`MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA`	`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

`PendingDeposit`

Note: The container is new in EIP7251.

class PendingDeposit(Container):
    pubkey: BLSPubkey
    withdrawal_credentials: Bytes32
    amount: Gwei
    signature: BLSSignature
    slot: Slot

`PendingPartialWithdrawal`

Note: The container is new in EIP7251.

class PendingPartialWithdrawal(Container):
    index: ValidatorIndex
    amount: Gwei
    withdrawable_epoch: Epoch

`PendingConsolidation`

Note: The container is new in EIP7251.

class PendingConsolidation(Container):
    source_index: ValidatorIndex
    target_index: ValidatorIndex

`DepositRequest`

Note: The container is new in EIP6110.

class DepositRequest(Container):
    pubkey: BLSPubkey
    withdrawal_credentials: Bytes32
    amount: Gwei
    signature: BLSSignature
    index: uint64

`WithdrawalRequest`

Note: The container is new in EIP7251:EIP7002.

class WithdrawalRequest(Container):
    source_address: ExecutionAddress
    validator_pubkey: BLSPubkey
    amount: Gwei

`ConsolidationRequest`

Note: The container is new in EIP7251.

class ConsolidationRequest(Container):
    source_address: ExecutionAddress
    source_pubkey: BLSPubkey
    target_pubkey: BLSPubkey

`SingleAttestation`

class SingleAttestation(Container):
    committee_index: CommitteeIndex
    attester_index: ValidatorIndex
    data: AttestationData
    signature: BLSSignature

`ExecutionRequests`

Note: This container holds requests from the execution layer that are received in ExecutionPayloadV4 via the Engine API. These requests are required for CL state transition (see BeaconBlockBody).

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]

Modified Containers

`AttesterSlashing`

class AttesterSlashing(Container):
    attestation_1: IndexedAttestation  # [Modified in Electra:EIP7549]
    attestation_2: IndexedAttestation  # [Modified in Electra:EIP7549]

`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_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`

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`

class IndexedAttestation(Container):
    # [Modified in Electra:EIP7549]
    attesting_indices: List[ValidatorIndex, MAX_VALIDATORS_PER_COMMITTEE * MAX_COMMITTEES_PER_SLOT]
    data: AttestationData
    signature: BLSSignature

`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]
    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.

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.

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`

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)

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.

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.

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`

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`

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`

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`

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`

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`

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.

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.

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.

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`

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`

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`

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`

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.

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.

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 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

Modified `process_slashings`

Note: The function process_slashings is modified to use a new algorithm to compute correlation penalty.

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`

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
        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:

All Eth1 bridge deposits are processed before the first deposit request gets processed.
Deposit position in the queue is finalized.
Deposit does not exceed the MAX_PENDING_DEPOSITS_PER_EPOCH limit.
Deposit does not exceed the activation churn limit.

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`

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.

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)

Execution engine

Request data

Modified `NewPayloadRequest`

@dataclass
class NewPayloadRequest(object):
    execution_payload: ExecutionPayload
    versioned_hashes: Sequence[VersionedHash]
    parent_beacon_block_root: Root
    execution_requests: ExecutionRequests  # [New in Electra]

Engine APIs

Modified `notify_new_payload`

Note: The function notify_new_payload is modified to include the additional execution_requests parameter in Electra.

def notify_new_payload(self: ExecutionEngine,
                       execution_payload: ExecutionPayload,
                       parent_beacon_block_root: Root,
                       execution_requests_list: Sequence[bytes]) -> bool:
    """
    Return ``True`` if and only if ``execution_payload`` and ``execution_requests``
    are valid with respect to ``self.execution_state``.
    """
    ...

Modified `verify_and_notify_new_payload`

Note: The function verify_and_notify_new_payload is modified to pass the additional parameter execution_requests when calling notify_new_payload in Electra.

def verify_and_notify_new_payload(self: ExecutionEngine,
                                  new_payload_request: NewPayloadRequest) -> bool:
    """
    Return ``True`` if and only if ``new_payload_request`` is valid with respect to ``self.execution_state``.
    """
    execution_payload = new_payload_request.execution_payload
    parent_beacon_block_root = new_payload_request.parent_beacon_block_root
    execution_requests_list = get_execution_requests_list(new_payload_request.execution_requests)  # [New in Electra]

    if not self.is_valid_block_hash(execution_payload, parent_beacon_block_root):
        return False

    if not self.is_valid_versioned_hashes(new_payload_request):
        return False

    # [Modified in Electra]
    if not self.notify_new_payload(
            execution_payload,
            parent_beacon_block_root,
            execution_requests_list):
        return False

    return True

Block processing

def process_block(state: BeaconState, block: BeaconBlock) -> None:
    process_block_header(state, block)
    process_withdrawals(state, block.body.execution_payload)  # [Modified in Electra:EIP7251]
    process_execution_payload(state, block.body, EXECUTION_ENGINE)  # [Modified in Electra:EIP6110]
    process_randao(state, block.body)
    process_eth1_data(state, block.body)
    process_operations(state, block.body)  # [Modified in Electra:EIP6110:EIP7002:EIP7549:EIP7251]
    process_sync_aggregate(state, block.body.sync_aggregate)

Withdrawals

Modified `get_expected_withdrawals`

Note: The function get_expected_withdrawals is modified to support EIP7251.

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] = []
    partial_withdrawals_count = 0

    # [New in Electra:EIP7251] Consume pending partial withdrawals
    for withdrawal in state.pending_partial_withdrawals:
        if withdrawal.withdrawable_epoch > epoch or len(withdrawals) == MAX_PENDING_PARTIALS_PER_WITHDRAWALS_SWEEP:
            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 += 1

    # 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_max_effective_balance(validator),  # [Modified in Electra: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

Modified `process_withdrawals`

Note: The function process_withdrawals is modified to support EIP7251.

def process_withdrawals(state: BeaconState, payload: ExecutionPayload) -> None:
    expected_withdrawals, partial_withdrawals_count = get_expected_withdrawals(state)  # [Modified in Electra:EIP7251]

    assert payload.withdrawals == expected_withdrawals

    for withdrawal in expected_withdrawals:
        decrease_balance(state, withdrawal.validator_index, withdrawal.amount)

    # Update pending partial withdrawals [New in Electra:EIP7251]
    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

Execution payload

New `get_execution_requests_list`

Note: Encodes execution requests as defined by EIP-7685.

def get_execution_requests_list(execution_requests: ExecutionRequests) -> Sequence[bytes]:
    deposit_bytes = ssz_serialize(execution_requests.deposits)
    withdrawal_bytes = ssz_serialize(execution_requests.withdrawals)
    consolidation_bytes = ssz_serialize(execution_requests.consolidations)

    return [deposit_bytes, withdrawal_bytes, consolidation_bytes]

Modified `process_execution_payload`

Note: The function process_execution_payload is modified to pass execution_requests into execution_engine.verify_and_notify_new_payload (via the updated NewPayloadRequest).

def process_execution_payload(state: BeaconState, body: BeaconBlockBody, execution_engine: ExecutionEngine) -> None:
    payload = body.execution_payload

    # Verify consistency of the parent hash with respect to the previous execution payload header
    assert payload.parent_hash == state.latest_execution_payload_header.block_hash
    # Verify prev_randao
    assert payload.prev_randao == get_randao_mix(state, get_current_epoch(state))
    # Verify timestamp
    assert payload.timestamp == compute_timestamp_at_slot(state, state.slot)
    # Verify commitments are under limit
    assert len(body.blob_kzg_commitments) <= MAX_BLOBS_PER_BLOCK
    # Verify the execution payload is valid
    versioned_hashes = [kzg_commitment_to_versioned_hash(commitment) for commitment in body.blob_kzg_commitments]
    assert execution_engine.verify_and_notify_new_payload(
        NewPayloadRequest(
            execution_payload=payload,
            versioned_hashes=versioned_hashes,
            parent_beacon_block_root=state.latest_block_header.parent_root,
            execution_requests=body.execution_requests,  # [New in Electra]
        )
    )
    # Cache execution payload header
    state.latest_execution_payload_header = ExecutionPayloadHeader(
        parent_hash=payload.parent_hash,
        fee_recipient=payload.fee_recipient,
        state_root=payload.state_root,
        receipts_root=payload.receipts_root,
        logs_bloom=payload.logs_bloom,
        prev_randao=payload.prev_randao,
        block_number=payload.block_number,
        gas_limit=payload.gas_limit,
        gas_used=payload.gas_used,
        timestamp=payload.timestamp,
        extra_data=payload.extra_data,
        base_fee_per_gas=payload.base_fee_per_gas,
        block_hash=payload.block_hash,
        transactions_root=hash_tree_root(payload.transactions),
        withdrawals_root=hash_tree_root(payload.withdrawals),
        blob_gas_used=payload.blob_gas_used,
        excess_blob_gas=payload.excess_blob_gas,
    )

Operations

Modified `process_operations`

Note: The function process_operations is modified to support all of the new functionality in Electra.

def process_operations(state: BeaconState, body: BeaconBlockBody) -> None:
    # [Modified in Electra:EIP6110]
    # Disable former deposit mechanism once all prior deposits are processed
    eth1_deposit_index_limit = min(state.eth1_data.deposit_count, state.deposit_requests_start_index)
    if state.eth1_deposit_index < eth1_deposit_index_limit:
        assert len(body.deposits) == min(MAX_DEPOSITS, eth1_deposit_index_limit - state.eth1_deposit_index)
    else:
        assert len(body.deposits) == 0

    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)  # [Modified in Electra:EIP7549]
    for_ops(body.deposits, process_deposit)
    for_ops(body.voluntary_exits, process_voluntary_exit)  # [Modified in Electra:EIP7251]
    for_ops(body.bls_to_execution_changes, process_bls_to_execution_change)
    for_ops(body.execution_requests.deposits, process_deposit_request)  # [New in Electra:EIP6110]
    for_ops(body.execution_requests.withdrawals, process_withdrawal_request)  # [New in Electra:EIP7002:EIP7251]
    for_ops(body.execution_requests.consolidations, process_consolidation_request)  # [New in Electra:EIP7251]

Attestations

Modified `process_attestation`

def process_attestation(state: BeaconState, attestation: Attestation) -> None:
    data = attestation.data
    assert data.target.epoch in (get_previous_epoch(state), get_current_epoch(state))
    assert data.target.epoch == compute_epoch_at_slot(data.slot)
    assert data.slot + MIN_ATTESTATION_INCLUSION_DELAY <= state.slot

    # [Modified in Electra:EIP7549]
    assert data.index == 0
    committee_indices = get_committee_indices(attestation.committee_bits)
    participants_count = 0
    for index in committee_indices:
        assert index < get_committee_count_per_slot(state, data.target.epoch)
        committee = get_beacon_committee(state, data.slot, index)
        participants_count += len(committee)

    assert len(attestation.aggregation_bits) == participants_count

    # Participation flag indices
    participation_flag_indices = get_attestation_participation_flag_indices(state, data, state.slot - data.slot)

    # Verify signature
    assert is_valid_indexed_attestation(state, get_indexed_attestation(state, attestation))

    # Update epoch participation flags
    if data.target.epoch == get_current_epoch(state):
        epoch_participation = state.current_epoch_participation
    else:
        epoch_participation = state.previous_epoch_participation

    proposer_reward_numerator = 0
    for index in get_attesting_indices(state, attestation):
        for flag_index, weight in enumerate(PARTICIPATION_FLAG_WEIGHTS):
            if flag_index in participation_flag_indices and not has_flag(epoch_participation[index], flag_index):
                epoch_participation[index] = add_flag(epoch_participation[index], flag_index)
                proposer_reward_numerator += get_base_reward(state, index) * weight

    # Reward proposer
    proposer_reward_denominator = (WEIGHT_DENOMINATOR - PROPOSER_WEIGHT) * WEIGHT_DENOMINATOR // PROPOSER_WEIGHT
    proposer_reward = Gwei(proposer_reward_numerator // proposer_reward_denominator)
    increase_balance(state, get_beacon_proposer_index(state), proposer_reward)

Deposits

Modified `get_validator_from_deposit`

Note: The function is modified to use MAX_EFFECTIVE_BALANCE_ELECTRA for compounding withdrawal credential.

def get_validator_from_deposit(pubkey: BLSPubkey, withdrawal_credentials: Bytes32, amount: uint64) -> Validator:
    validator = Validator(
        pubkey=pubkey,
        withdrawal_credentials=withdrawal_credentials,
        effective_balance=Gwei(0),
        slashed=False,
        activation_eligibility_epoch=FAR_FUTURE_EPOCH,
        activation_epoch=FAR_FUTURE_EPOCH,
        exit_epoch=FAR_FUTURE_EPOCH,
        withdrawable_epoch=FAR_FUTURE_EPOCH,
    )

    # [Modified in Electra:EIP7251]
    max_effective_balance = get_max_effective_balance(validator)
    validator.effective_balance = min(amount - amount % EFFECTIVE_BALANCE_INCREMENT, max_effective_balance)

    return validator

Modified `add_validator_to_registry`

Note: The function add_validator_to_registry is modified to use the modified get_validator_from_deposit.

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)  # [Modified in Electra:EIP7251]
    set_or_append_list(state.validators, index, validator)
    set_or_append_list(state.balances, index, amount)
    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))

Modified `apply_deposit`

Note: The function apply_deposit is modified to support EIP7251.

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, Gwei(0))  # [Modified in Electra:EIP7251]
            # [New in Electra:EIP7251]
            state.pending_deposits.append(PendingDeposit(
                pubkey=pubkey,
                withdrawal_credentials=withdrawal_credentials,
                amount=amount,
                signature=signature,
                slot=GENESIS_SLOT,  # Use GENESIS_SLOT to distinguish from a pending deposit request
            ))
    else:
        # Increase balance by deposit amount
        # [Modified in Electra:EIP7251]
        state.pending_deposits.append(PendingDeposit(
            pubkey=pubkey,
            withdrawal_credentials=withdrawal_credentials,
            amount=amount,
            signature=signature,
            slot=GENESIS_SLOT  # Use GENESIS_SLOT to distinguish from a pending deposit request
        ))

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 `process_deposit`

Note: The function process_deposit is modified to to use the modified apply_deposit.

def process_deposit(state: BeaconState, deposit: Deposit) -> None:
    # Verify the Merkle branch
    assert is_valid_merkle_branch(
        leaf=hash_tree_root(deposit.data),
        branch=deposit.proof,
        depth=DEPOSIT_CONTRACT_TREE_DEPTH + 1,  # Add 1 for the List length mix-in
        index=state.eth1_deposit_index,
        root=state.eth1_data.deposit_root,
    )

    # Deposits must be processed in order
    state.eth1_deposit_index += 1

    # [Modified in Electra:EIP7251]
    apply_deposit(
        state=state,
        pubkey=deposit.data.pubkey,
        withdrawal_credentials=deposit.data.withdrawal_credentials,
        amount=deposit.data.amount,
        signature=deposit.data.signature,
    )

Voluntary exits

Modified `process_voluntary_exit`

Note: The function process_voluntary_exit is modified to ensure the validator has no pending withdrawals in the queue.

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 Electra: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)

Execution layer withdrawal requests

New `process_withdrawal_request`

def process_withdrawal_request(
    state: BeaconState,
    withdrawal_request: WithdrawalRequest
) -> None:
    amount = withdrawal_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]
    # Verify pubkey exists
    request_pubkey = withdrawal_request.validator_pubkey
    if request_pubkey not in validator_pubkeys:
        return
    index = ValidatorIndex(validator_pubkeys.index(request_pubkey))
    validator = state.validators[index]

    # Verify withdrawal credentials
    has_correct_credential = has_execution_withdrawal_credential(validator)
    is_correct_source_address = (
        validator.withdrawal_credentials[12:] == withdrawal_request.source_address
    )
    if not (has_correct_credential and is_correct_source_address):
        return
    # Verify the validator is active
    if not is_active_validator(validator, get_current_epoch(state)):
        return
    # Verify exit has not been initiated
    if validator.exit_epoch != FAR_FUTURE_EPOCH:
        return
    # Verify the validator has been active long enough
    if 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,
        ))

Deposit requests

New `process_deposit_request`

def process_deposit_request(state: BeaconState, deposit_request: DepositRequest) -> None:
    # Set deposit request start index
    if state.deposit_requests_start_index == UNSET_DEPOSIT_REQUESTS_START_INDEX:
        state.deposit_requests_start_index = deposit_request.index

    # Create pending deposit
    state.pending_deposits.append(PendingDeposit(
        pubkey=deposit_request.pubkey,
        withdrawal_credentials=deposit_request.withdrawal_credentials,
        amount=deposit_request.amount,
        signature=deposit_request.signature,
        slot=state.slot,
    ))

Execution layer consolidation requests

New `is_valid_switch_to_compounding_request`

def is_valid_switch_to_compounding_request(
    state: BeaconState,
    consolidation_request: ConsolidationRequest
) -> bool:
    # Switch to compounding requires source and target be equal
    if consolidation_request.source_pubkey != consolidation_request.target_pubkey:
        return False

    # Verify pubkey exists
    source_pubkey = consolidation_request.source_pubkey
    validator_pubkeys = [v.pubkey for v in state.validators]
    if source_pubkey not in validator_pubkeys:
        return False

    source_validator = state.validators[ValidatorIndex(validator_pubkeys.index(source_pubkey))]

    # Verify request has been authorized
    if source_validator.withdrawal_credentials[12:] != consolidation_request.source_address:
        return False

    # Verify source withdrawal credentials
    if not has_eth1_withdrawal_credential(source_validator):
        return False

    # Verify the source is active
    current_epoch = get_current_epoch(state)
    if not is_active_validator(source_validator, current_epoch):
        return False

    # Verify exit for source has not been initiated
    if source_validator.exit_epoch != FAR_FUTURE_EPOCH:
        return False

    return True

New `process_consolidation_request`

def process_consolidation_request(
    state: BeaconState,
    consolidation_request: ConsolidationRequest
) -> None:
    if is_valid_switch_to_compounding_request(state, consolidation_request):
        validator_pubkeys = [v.pubkey for v in state.validators]
        request_source_pubkey = consolidation_request.source_pubkey
        source_index = ValidatorIndex(validator_pubkeys.index(request_source_pubkey))
        switch_to_compounding_validator(state, source_index)
        return

    # Verify that source != target, so a consolidation cannot be used as an exit.
    if consolidation_request.source_pubkey == consolidation_request.target_pubkey:
        return
    # If the pending consolidations queue is full, consolidation requests are ignored
    if len(state.pending_consolidations) == PENDING_CONSOLIDATIONS_LIMIT:
        return
    # If there is too little available consolidation churn limit, consolidation requests are ignored
    if get_consolidation_churn_limit(state) <= MIN_ACTIVATION_BALANCE:
        return

    validator_pubkeys = [v.pubkey for v in state.validators]
    # Verify pubkeys exists
    request_source_pubkey = consolidation_request.source_pubkey
    request_target_pubkey = consolidation_request.target_pubkey
    if request_source_pubkey not in validator_pubkeys:
        return
    if request_target_pubkey not in validator_pubkeys:
        return
    source_index = ValidatorIndex(validator_pubkeys.index(request_source_pubkey))
    target_index = ValidatorIndex(validator_pubkeys.index(request_target_pubkey))
    source_validator = state.validators[source_index]
    target_validator = state.validators[target_index]

    # Verify source withdrawal credentials
    has_correct_credential = has_execution_withdrawal_credential(source_validator)
    is_correct_source_address = (
        source_validator.withdrawal_credentials[12:] == consolidation_request.source_address
    )
    if not (has_correct_credential and is_correct_source_address):
        return

    # Verify that target has execution withdrawal credentials
    if not has_execution_withdrawal_credential(target_validator):
        return

    # Verify the source and the target are active
    current_epoch = get_current_epoch(state)
    if not is_active_validator(source_validator, current_epoch):
        return
    if not is_active_validator(target_validator, current_epoch):
        return
    # Verify exits for source and target have not been initiated
    if source_validator.exit_epoch != FAR_FUTURE_EPOCH:
        return
    if target_validator.exit_epoch != FAR_FUTURE_EPOCH:
        return

    # 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=source_index,
        target_index=target_index
    ))

    # Churn any target excess active balance of target and raise its max
    if has_eth1_withdrawal_credential(target_validator):
        switch_to_compounding_validator(state, target_index)

Testing

Note: The function initialize_beacon_state_from_eth1 is modified for pure Electra testing only. Modifications include:

Use ELECTRA_FORK_VERSION as the previous and current fork version.
Utilize the Electra BeaconBlockBody when constructing the initial latest_block_header.
[New in Electra:EIP6110] Add deposit_requests_start_index variable to the genesis state initialization.
[New in Electra:EIP7251] Initialize new fields to support increasing the maximum effective balance.

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=ELECTRA_FORK_VERSION,  # [Modified in Electra:EIP6110] for testing only
        current_version=ELECTRA_FORK_VERSION,  # [Modified in Electra:EIP6110]
        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
        deposit_requests_start_index=UNSET_DEPOSIT_REQUESTS_START_INDEX,  # [New in Electra:EIP6110]
    )

    # 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
    validator_pubkeys = [v.pubkey for v in state.validators]
    for deposit in state.pending_deposits:
        validator_index = ValidatorIndex(validator_pubkeys.index(deposit.pubkey))
        increase_balance(state, validator_index, deposit.amount)
    state.pending_deposits = []

    # Process activations
    for index, validator in enumerate(state.validators):
        balance = state.balances[index]
        # [Modified in Electra:EIP7251]
        validator.effective_balance = min(
            balance - balance % EFFECTIVE_BALANCE_INCREMENT, get_max_effective_balance(validator))
        if validator.effective_balance >= MIN_ACTIVATION_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
    state.latest_execution_payload_header = execution_payload_header

    return state

Files

beacon-chain.md

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Electra -- The Beacon Chain

Table of contents

Introduction

Constants

Misc

Withdrawal prefixes

Preset

Gwei values

Rewards and penalties

State list lengths

Max operations per block

Execution

Withdrawals processing

Pending deposits processing

Configuration

Validator cycle

Containers

New containers

PendingDeposit

PendingPartialWithdrawal

PendingConsolidation

DepositRequest

WithdrawalRequest

ConsolidationRequest

SingleAttestation

ExecutionRequests

Modified Containers

AttesterSlashing

BeaconBlockBody

Extended Containers

Attestation

IndexedAttestation

BeaconState

Helper functions

Predicates

Modified compute_proposer_index

Modified is_eligible_for_activation_queue

New is_compounding_withdrawal_credential

New has_compounding_withdrawal_credential

New has_execution_withdrawal_credential

Modified is_fully_withdrawable_validator

Modified is_partially_withdrawable_validator

Misc

New get_committee_indices

New get_max_effective_balance

Beacon state accessors

New get_balance_churn_limit

New get_activation_exit_churn_limit

New get_consolidation_churn_limit

New get_pending_balance_to_withdraw

Modified get_attesting_indices

Modified get_next_sync_committee_indices

Beacon state mutators

Modified initiate_validator_exit

New switch_to_compounding_validator

New queue_excess_active_balance

New compute_exit_epoch_and_update_churn

New compute_consolidation_epoch_and_update_churn

Modified slash_validator

Beacon chain state transition function

Epoch processing

Modified process_epoch

Modified process_registry_updates

Modified process_slashings

New apply_pending_deposit

New process_pending_deposits

New process_pending_consolidations

Modified process_effective_balance_updates

Execution engine

Request data

Modified NewPayloadRequest

Engine APIs

Modified notify_new_payload

Modified verify_and_notify_new_payload

`PendingDeposit`

`PendingPartialWithdrawal`

`PendingConsolidation`

`DepositRequest`

`WithdrawalRequest`

`ConsolidationRequest`

`SingleAttestation`

`ExecutionRequests`

`AttesterSlashing`

`BeaconBlockBody`

`Attestation`

`IndexedAttestation`

`BeaconState`

Modified `compute_proposer_index`

Modified `is_eligible_for_activation_queue`

New `is_compounding_withdrawal_credential`

New `has_compounding_withdrawal_credential`

New `has_execution_withdrawal_credential`

Modified `is_fully_withdrawable_validator`

Modified `is_partially_withdrawable_validator`

New `get_committee_indices`

New `get_max_effective_balance`

New `get_balance_churn_limit`

New `get_activation_exit_churn_limit`

New `get_consolidation_churn_limit`

New `get_pending_balance_to_withdraw`

Modified `get_attesting_indices`

Modified `get_next_sync_committee_indices`

Modified `initiate_validator_exit`

New `switch_to_compounding_validator`

New `queue_excess_active_balance`

New `compute_exit_epoch_and_update_churn`

New `compute_consolidation_epoch_and_update_churn`

Modified `slash_validator`

Modified `process_epoch`

Modified `process_registry_updates`

Modified `process_slashings`

New `apply_pending_deposit`

New `process_pending_deposits`

New `process_pending_consolidations`

Modified `process_effective_balance_updates`

Modified `NewPayloadRequest`

Modified `notify_new_payload`

Modified `verify_and_notify_new_payload`

Modified `get_expected_withdrawals`

Modified `process_withdrawals`

New `get_execution_requests_list`

Modified `process_execution_payload`

Modified `process_operations`

Modified `process_attestation`

Modified `get_validator_from_deposit`

Modified `add_validator_to_registry`

Modified `apply_deposit`

New `is_valid_deposit_signature`

Modified `process_deposit`

Modified `process_voluntary_exit`

New `process_withdrawal_request`

New `process_deposit_request`

New `is_valid_switch_to_compounding_request`

New `process_consolidation_request`