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Electra -- The Beacon Chain

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

Table of contents

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 * EIP-7691: Blob throughput increase

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] Value which indicates no start index has been assigned
FULL_EXIT_REQUEST_AMOUNT uint64(0) [New in Electra:EIP7002] Withdrawal amount used to signal a full validator exit

Withdrawal prefixes

Name Value Description
COMPOUNDING_WITHDRAWAL_PREFIX Bytes1('0x02') [New in Electra:EIP7251] Withdrawal credential prefix for a compounding validator

Execution layer triggered requests

Name Value
DEPOSIT_REQUEST_TYPE Bytes1('0x00')
WITHDRAWAL_REQUEST_TYPE Bytes1('0x01')
CONSOLIDATION_REQUEST_TYPE Bytes1('0x02')

Preset

Gwei values

Name Value Description
MIN_ACTIVATION_BALANCE Gwei(2**5 * 10**9) (= 32,000,000,000) [New in Electra:EIP7251] Minimum balance for a validator to become active
MAX_EFFECTIVE_BALANCE_ELECTRA Gwei(2**11 * 10**9) (= 2048,000,000,000) [New in Electra:EIP7251] Maximum effective balance for a compounding validator

Rewards and penalties

Name Value
MIN_SLASHING_PENALTY_QUOTIENT_ELECTRA uint64(2**12) (= 4,096)
WHISTLEBLOWER_REWARD_QUOTIENT_ELECTRA uint64(2**12) (= 4,096)

State list lengths

Name Value Unit
PENDING_DEPOSITS_LIMIT uint64(2**27) (= 134,217,728) pending deposits
PENDING_PARTIAL_WITHDRAWALS_LIMIT uint64(2**27) (= 134,217,728) pending partial withdrawals
PENDING_CONSOLIDATIONS_LIMIT uint64(2**18) (= 262,144) pending consolidations

Max operations per block

Name Value
MAX_ATTESTER_SLASHINGS_ELECTRA 2**0 (= 1)
MAX_ATTESTATIONS_ELECTRA 2**3 (= 8)

Execution

Name Value Description
MAX_DEPOSIT_REQUESTS_PER_PAYLOAD uint64(2**13) (= 8,192) [New in Electra:EIP6110] Maximum number of execution layer deposit requests in each payload
MAX_WITHDRAWAL_REQUESTS_PER_PAYLOAD uint64(2**4) (= 16) [New in Electra:EIP7002] Maximum number of execution layer withdrawal requests in each payload
MAX_CONSOLIDATION_REQUESTS_PER_PAYLOAD uint64(2**1) (= 2) [New in Electra:EIP7251] Maximum number of execution layer consolidation requests in each payload

Withdrawals processing

Name Value Description
MAX_PENDING_PARTIALS_PER_WITHDRAWALS_SWEEP uint64(2**3) (= 8) [New in Electra:EIP7002] Maximum number of pending partial withdrawals to process per payload

Pending deposits processing

Name Value Description
MAX_PENDING_DEPOSITS_PER_EPOCH uint64(2**4) (= 16) [New in Electra:EIP6110] Maximum number of pending deposits to process per epoch

Configuration

Execution

Name Value Description
MAX_BLOBS_PER_BLOCK_ELECTRA uint64(9) [New in Electra:EIP7691] Maximum number of blobs in a single block limited by MAX_BLOB_COMMITMENTS_PER_BLOCK

Validator cycle

Name Value
MIN_PER_EPOCH_CHURN_LIMIT_ELECTRA Gwei(2**7 * 10**9) (= 128,000,000,000)
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.

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

PendingPartialWithdrawal

Note: The container is new in EIP7251.

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

PendingConsolidation

Note: The container is new in EIP7251.

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

DepositRequest

Note: The container is new in EIP6110.

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

WithdrawalRequest

Note: The container is new in EIP7251:EIP7002.

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

ConsolidationRequest

Note: The container is new in EIP7251.

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

ExecutionRequests

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

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class ExecutionRequests(Container):
    deposits: List[DepositRequest, MAX_DEPOSIT_REQUESTS_PER_PAYLOAD]  # [New in Electra:EIP6110]
    withdrawals: List[WithdrawalRequest, MAX_WITHDRAWAL_REQUESTS_PER_PAYLOAD]  # [New in Electra:EIP7002:EIP7251]
    consolidations: List[ConsolidationRequest, MAX_CONSOLIDATION_REQUESTS_PER_PAYLOAD]  # [New in Electra:EIP7251]

SingleAttestation

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

Modified Containers

AttesterSlashing

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

BeaconBlockBody

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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

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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

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

BeaconState

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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 and to use a 16-bit random value instead of an 8-bit random byte in the effective balance filter.

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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_VALUE = 2**16 - 1  # [Modified in Electra]
    i = uint64(0)
    total = uint64(len(indices))
    while True:
        candidate_index = indices[compute_shuffled_index(i % total, total, seed)]
        # [Modified in Electra]
        random_bytes = hash(seed + uint_to_bytes(i // 16))
        offset = i % 16 * 2
        random_value = bytes_to_uint64(random_bytes[offset:offset + 2])
        effective_balance = state.validators[candidate_index].effective_balance
        # [Modified in Electra:EIP7251]
        if effective_balance * MAX_RANDOM_VALUE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_value:
            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.

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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

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def is_compounding_withdrawal_credential(withdrawal_credentials: Bytes32) -> bool:
    return withdrawal_credentials[:1] == COMPOUNDING_WITHDRAWAL_PREFIX

New has_compounding_withdrawal_credential

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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

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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.

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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.

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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

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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

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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

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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

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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

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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

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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.validator_index == validator_index
    )

Modified get_attesting_indices

Note: The function get_attesting_indices is modified to support EIP7549.

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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 and to use a 16-bit random value instead of an 8-bit random byte in the effective balance filter.

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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_VALUE = 2**16 - 1  # [Modified in Electra]
    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 = uint64(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]
        # [Modified in Electra]
        random_bytes = hash(seed + uint_to_bytes(i // 16))
        offset = i % 16 * 2
        random_value = bytes_to_uint64(random_bytes[offset:offset + 2])
        effective_balance = state.validators[candidate_index].effective_balance
        # [Modified in Electra:EIP7251]
        if effective_balance * MAX_RANDOM_VALUE >= MAX_EFFECTIVE_BALANCE_ELECTRA * random_value:
            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.

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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

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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

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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

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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

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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.

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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.

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def process_epoch(state: BeaconState) -> None:
    process_justification_and_finalization(state)
    process_inactivity_updates(state)
    process_rewards_and_penalties(state)
    process_registry_updates(state)  # [Modified in Electra:EIP7251]
    process_slashings(state)  # [Modified in Electra:EIP7251]
    process_eth1_data_reset(state)
    process_pending_deposits(state)  # [New in Electra:EIP7251]
    process_pending_consolidations(state)  # [New in Electra:EIP7251]
    process_effective_balance_updates(state)  # [Modified in Electra:EIP7251]
    process_slashings_reset(state)
    process_randao_mixes_reset(state)
    process_historical_summaries_update(state)
    process_participation_flag_updates(state)
    process_sync_committee_updates(state)

Modified process_registry_updates

Note: The function process_registry_updates is modified to use the updated definitions of initiate_validator_exit and is_eligible_for_activation_queue and changes how the activation epochs are computed for eligible validators.

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def process_registry_updates(state: BeaconState) -> None:
    # Process activation eligibility and ejections
    for index, validator in enumerate(state.validators):
        if is_eligible_for_activation_queue(validator):  # [Modified in Electra:EIP7251]
            validator.activation_eligibility_epoch = get_current_epoch(state) + 1

        if (
            is_active_validator(validator, get_current_epoch(state))
            and validator.effective_balance <= EJECTION_BALANCE
        ):
            initiate_validator_exit(state, ValidatorIndex(index))  # [Modified in Electra:EIP7251]

    # Activate all eligible validators
    # [Modified in Electra:EIP7251]
    activation_epoch = compute_activation_exit_epoch(get_current_epoch(state))
    for validator in state.validators:
        if is_eligible_for_activation(state, validator):
            validator.activation_epoch = activation_epoch

Modified process_slashings

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

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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

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def apply_pending_deposit(state: BeaconState, deposit: PendingDeposit) -> None:
    """
    Applies ``deposit`` to the ``state``.
    """
    validator_pubkeys = [v.pubkey for v in state.validators]
    if deposit.pubkey not in validator_pubkeys:
        # Verify the deposit signature (proof of possession) which is not checked by the deposit contract
        if is_valid_deposit_signature(
            deposit.pubkey,
            deposit.withdrawal_credentials,
            deposit.amount,
            deposit.signature
        ):
            add_validator_to_registry(state, deposit.pubkey, deposit.withdrawal_credentials, deposit.amount)
    else:
        validator_index = ValidatorIndex(validator_pubkeys.index(deposit.pubkey))
        increase_balance(state, validator_index, deposit.amount)

New process_pending_deposits

Iterating over pending_deposits queue this function runs the following checks before applying pending deposit: 1. All Eth1 bridge deposits are processed before the first deposit request gets processed. 2. Deposit position in the queue is finalized. 3. Deposit does not exceed the MAX_PENDING_DEPOSITS_PER_EPOCH limit. 4. Deposit does not exceed the activation churn limit.

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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

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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
        source_effective_balance = min(
            state.balances[pending_consolidation.source_index], source_validator.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.

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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
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@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 is_valid_block_hash

Note: The function is_valid_block_hash is modified to include the additional execution_requests_list.

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def is_valid_block_hash(self: ExecutionEngine,
                        execution_payload: ExecutionPayload,
                        parent_beacon_block_root: Root,
                        execution_requests_list: Sequence[bytes]) -> bool:
    """
    Return ``True`` if and only if ``execution_payload.block_hash`` is computed correctly.
    """
    ...
Modified notify_new_payload

Note: The function notify_new_payload is modified to include the additional execution_requests_list.

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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_list``
    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_list when calling is_valid_block_hash and notify_new_payload in Electra.

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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 b'' in execution_payload.transactions:
        return False

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

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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.

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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] = []
    processed_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.validator_index]
        has_sufficient_effective_balance = validator.effective_balance >= MIN_ACTIVATION_BALANCE
        has_excess_balance = state.balances[withdrawal.validator_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.validator_index] - MIN_ACTIVATION_BALANCE,
                withdrawal.amount)
            withdrawals.append(Withdrawal(
                index=withdrawal_index,
                validator_index=withdrawal.validator_index,
                address=ExecutionAddress(validator.withdrawal_credentials[12:]),
                amount=withdrawable_balance,
            ))
            withdrawal_index += WithdrawalIndex(1)

        processed_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]
        # [Modified in Electra:EIP7251]
        partially_withdrawn_balance = sum(
            withdrawal.amount for withdrawal in withdrawals if withdrawal.validator_index == validator_index)
        balance = state.balances[validator_index] - partially_withdrawn_balance
        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, processed_partial_withdrawals_count
Modified process_withdrawals

Note: The function process_withdrawals is modified to support EIP7251.

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

    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[processed_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.

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def get_execution_requests_list(execution_requests: ExecutionRequests) -> Sequence[bytes]:
    requests = [
        (DEPOSIT_REQUEST_TYPE, execution_requests.deposits),
        (WITHDRAWAL_REQUEST_TYPE, execution_requests.withdrawals),
        (CONSOLIDATION_REQUEST_TYPE, execution_requests.consolidations),
    ]

    return [
        request_type + ssz_serialize(request_data)
        for request_type, request_data in requests
        if len(request_data) != 0
    ]
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).

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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_ELECTRA  # [Modified in Electra:EIP7691]
    # 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.

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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

Note: The function is modified to support EIP7549.

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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)
    committee_offset = 0
    for committee_index in committee_indices:
        assert committee_index < get_committee_count_per_slot(state, data.target.epoch)
        committee = get_beacon_committee(state, data.slot, committee_index)
        committee_attesters = set(
            attester_index for i, attester_index in enumerate(committee)
            if attestation.aggregation_bits[committee_offset + i]
        )
        assert len(committee_attesters) > 0
        committee_offset += len(committee)

    # Bitfield length matches total number of participants
    assert len(attestation.aggregation_bits) == committee_offset

    # 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.

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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.

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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.

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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]
        else:
            return

    # 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
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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.

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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.

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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
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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(
            validator_index=index,
            amount=to_withdraw,
            withdrawable_epoch=withdrawable_epoch,
        ))
Deposit requests
New process_deposit_request
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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
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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
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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 compounding withdrawal credentials
    if not has_compounding_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
    # Verify the source has been active long enough
    if current_epoch < source_validator.activation_epoch + SHARD_COMMITTEE_PERIOD:
        return
    # Verify the source has no pending withdrawals in the queue
    if get_pending_balance_to_withdraw(state, source_index) > 0:
        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
    ))