# EIP-7732 -- The Beacon Chain ## Table of contents - [Introduction](#introduction) - [Constants](#constants) - [Payload status](#payload-status) - [Preset](#preset) - [Misc](#misc) - [Domain types](#domain-types) - [Max operations per block](#max-operations-per-block) - [Containers](#containers) - [New containers](#new-containers) - [`PayloadAttestationData`](#payloadattestationdata) - [`PayloadAttestation`](#payloadattestation) - [`PayloadAttestationMessage`](#payloadattestationmessage) - [`IndexedPayloadAttestation`](#indexedpayloadattestation) - [`SignedExecutionPayloadHeader`](#signedexecutionpayloadheader) - [`ExecutionPayloadEnvelope`](#executionpayloadenvelope) - [`SignedExecutionPayloadEnvelope`](#signedexecutionpayloadenvelope) - [Modified containers](#modified-containers) - [`BeaconBlockBody`](#beaconblockbody) - [`ExecutionPayloadHeader`](#executionpayloadheader) - [`BeaconState`](#beaconstate) - [Helper functions](#helper-functions) - [Math](#math) - [`bit_floor`](#bit_floor) - [Misc](#misc-1) - [`remove_flag`](#remove_flag) - [Predicates](#predicates) - [`is_valid_indexed_payload_attestation`](#is_valid_indexed_payload_attestation) - [`is_parent_block_full`](#is_parent_block_full) - [Beacon State accessors](#beacon-state-accessors) - [`get_ptc`](#get_ptc) - [Modified `get_attesting_indices`](#modified-get_attesting_indices) - [`get_payload_attesting_indices`](#get_payload_attesting_indices) - [`get_indexed_payload_attestation`](#get_indexed_payload_attestation) - [Beacon chain state transition function](#beacon-chain-state-transition-function) - [Block processing](#block-processing) - [Withdrawals](#withdrawals) - [Modified `process_withdrawals`](#modified-process_withdrawals) - [Execution payload header](#execution-payload-header) - [New `verify_execution_payload_header_signature`](#new-verify_execution_payload_header_signature) - [New `process_execution_payload_header`](#new-process_execution_payload_header) - [Operations](#operations) - [Modified `process_operations`](#modified-process_operations) - [Payload Attestations](#payload-attestations) - [`process_payload_attestation`](#process_payload_attestation) - [Modified `process_execution_payload`](#modified-process_execution_payload) - [New `verify_execution_payload_envelope_signature`](#new-verify_execution_payload_envelope_signature) ## Introduction This is the beacon chain specification of the enshrined proposer builder separation feature. *Note:* This specification is built upon [Electra](../../electra/beacon-chain.md) and is under active development. This feature adds new staked consensus participants called *Builders* and new honest validators duties called *payload timeliness attestations*. The slot is divided in **four** intervals. Honest validators gather *signed bids* (a `SignedExecutionPayloadHeader`) from builders and submit their consensus blocks (a `SignedBeaconBlock`) including these bids at the beginning of the slot. At the start of the second interval, honest validators submit attestations just as they do previous to this feature). At the start of the third interval, aggregators aggregate these attestations and the builder broadcasts either a full payload or a message indicating that they are withholding the payload (a `SignedExecutionPayloadEnvelope`). At the start of the fourth interval, some validators selected to be members of the new **Payload Timeliness Committee** (PTC) attest to the presence and timeliness of the builder's payload. At any given slot, the status of the blockchain's head may be either - A block from a previous slot (e.g. the current slot's proposer did not submit its block). - An *empty* block from the current slot (e.g. the proposer submitted a timely block, but the builder did not reveal the payload on time). - A full block for the current slot (both the proposer and the builder revealed on time). ## Constants ### Payload status | Name | Value | | - | - | | `PAYLOAD_ABSENT` | `uint8(0)` | | `PAYLOAD_PRESENT` | `uint8(1)` | | `PAYLOAD_WITHHELD` | `uint8(2)` | | `PAYLOAD_INVALID_STATUS` | `uint8(3)` | ## Preset ### Misc | Name | Value | | - | - | | `PTC_SIZE` | `uint64(2**9)` (=512) # (New in EIP-7732) | ### Domain types | Name | Value | | - | - | | `DOMAIN_BEACON_BUILDER` | `DomainType('0x1B000000')` # (New in EIP-7732)| | `DOMAIN_PTC_ATTESTER` | `DomainType('0x0C000000')` # (New in EIP-7732)| ### Max operations per block | Name | Value | | - | - | | `MAX_PAYLOAD_ATTESTATIONS` | `2**2` (= 4) # (New in EIP-7732) | ## Containers ### New containers #### `PayloadAttestationData` ```python class PayloadAttestationData(Container): beacon_block_root: Root slot: Slot payload_status: uint8 ``` #### `PayloadAttestation` ```python class PayloadAttestation(Container): aggregation_bits: Bitvector[PTC_SIZE] data: PayloadAttestationData signature: BLSSignature ``` #### `PayloadAttestationMessage` ```python class PayloadAttestationMessage(Container): validator_index: ValidatorIndex data: PayloadAttestationData signature: BLSSignature ``` #### `IndexedPayloadAttestation` ```python class IndexedPayloadAttestation(Container): attesting_indices: List[ValidatorIndex, PTC_SIZE] data: PayloadAttestationData signature: BLSSignature ``` #### `SignedExecutionPayloadHeader` ```python class SignedExecutionPayloadHeader(Container): message: ExecutionPayloadHeader signature: BLSSignature ``` #### `ExecutionPayloadEnvelope` ```python class ExecutionPayloadEnvelope(Container): payload: ExecutionPayload builder_index: ValidatorIndex beacon_block_root: Root blob_kzg_commitments: List[KZGCommitment, MAX_BLOB_COMMITMENTS_PER_BLOCK] payload_withheld: boolean state_root: Root ``` #### `SignedExecutionPayloadEnvelope` ```python class SignedExecutionPayloadEnvelope(Container): message: ExecutionPayloadEnvelope signature: BLSSignature ``` ### Modified containers #### `BeaconBlockBody` **Note:** The Beacon Block body is modified to contain a `Signed ExecutionPayloadHeader`. The containers `BeaconBlock` and `SignedBeaconBlock` are modified indirectly. ```python class BeaconBlockBody(Container): randao_reveal: BLSSignature eth1_data: Eth1Data # Eth1 data vote graffiti: Bytes32 # Arbitrary data # Operations proposer_slashings: List[ProposerSlashing, MAX_PROPOSER_SLASHINGS] attester_slashings: List[AttesterSlashing, MAX_ATTESTER_SLASHINGS] attestations: List[Attestation, MAX_ATTESTATIONS] deposits: List[Deposit, MAX_DEPOSITS] voluntary_exits: List[SignedVoluntaryExit, MAX_VOLUNTARY_EXITS] sync_aggregate: SyncAggregate # Execution # Removed execution_payload [Removed in EIP-7732] # Removed blob_kzg_commitments [Removed in EIP-7732] bls_to_execution_changes: List[SignedBLSToExecutionChange, MAX_BLS_TO_EXECUTION_CHANGES] # PBS signed_execution_payload_header: SignedExecutionPayloadHeader # [New in EIP-7732] payload_attestations: List[PayloadAttestation, MAX_PAYLOAD_ATTESTATIONS] # [New in EIP-7732] ``` #### `ExecutionPayloadHeader` **Note:** The `ExecutionPayloadHeader` is modified to only contain the block hash of the committed `ExecutionPayload` in addition to the builder's payment information, gas limit and KZG commitments root to verify the inclusion proofs. ```python class ExecutionPayloadHeader(Container): parent_block_hash: Hash32 parent_block_root: Root block_hash: Hash32 gas_limit: uint64 builder_index: ValidatorIndex slot: Slot value: Gwei blob_kzg_commitments_root: Root ``` #### `BeaconState` *Note*: The `BeaconState` is modified to track the last withdrawals honored in the CL. The `latest_execution_payload_header` is modified semantically to refer not to a past committed `ExecutionPayload` but instead it corresponds to the state's slot builder's bid. Another addition is to track the last committed block hash and the last slot that was full, that is in which there were both consensus and execution blocks included. ```python class BeaconState(Container): # Versioning genesis_time: uint64 genesis_validators_root: Root slot: Slot fork: Fork # History latest_block_header: BeaconBlockHeader block_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT] state_roots: Vector[Root, SLOTS_PER_HISTORICAL_ROOT] historical_roots: List[Root, HISTORICAL_ROOTS_LIMIT] # Frozen in Capella, replaced by historical_summaries # 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 deposit_balance_to_consume: Gwei exit_balance_to_consume: Gwei earliest_exit_epoch: Epoch consolidation_balance_to_consume: Gwei earliest_consolidation_epoch: Epoch pending_balance_deposits: List[PendingBalanceDeposit, PENDING_BALANCE_DEPOSITS_LIMIT] pending_partial_withdrawals: List[PendingPartialWithdrawal, PENDING_PARTIAL_WITHDRAWALS_LIMIT] pending_consolidations: List[PendingConsolidation, PENDING_CONSOLIDATIONS_LIMIT] # PBS latest_block_hash: Hash32 # [New in EIP-7732] latest_full_slot: Slot # [New in EIP-7732] latest_withdrawals_root: Root # [New in EIP-7732] ``` ## Helper functions ### Math #### `bit_floor` ```python def bit_floor(n: uint64) -> uint64: """ if ``n`` is not zero, returns the largest power of `2` that is not greater than `n`. """ if n == 0: return 0 return uint64(1) << (n.bit_length() - 1) ``` ### Misc #### `remove_flag` ```python def remove_flag(flags: ParticipationFlags, flag_index: int) -> ParticipationFlags: flag = ParticipationFlags(2**flag_index) return flags & ~flag ``` ### Predicates #### `is_valid_indexed_payload_attestation` ```python def is_valid_indexed_payload_attestation( state: BeaconState, indexed_payload_attestation: IndexedPayloadAttestation) -> bool: """ Check if ``indexed_payload_attestation`` is not empty, has sorted and unique indices and has a valid aggregate signature. """ # Verify the data is valid if indexed_payload_attestation.data.payload_status >= PAYLOAD_INVALID_STATUS: return False # Verify indices are sorted and unique indices = indexed_payload_attestation.attesting_indices if len(indices) == 0 or not indices == sorted(set(indices)): return False # Verify aggregate signature pubkeys = [state.validators[i].pubkey for i in indices] domain = get_domain(state, DOMAIN_PTC_ATTESTER, None) signing_root = compute_signing_root(indexed_payload_attestation.data, domain) return bls.FastAggregateVerify(pubkeys, signing_root, indexed_payload_attestation.signature) ``` #### `is_parent_block_full` This function returns true if the last committed payload header was fulfilled with a payload, this can only happen when both beacon block and payload were present. This function must be called on a beacon state before processing the execution payload header in the block. ```python def is_parent_block_full(state: BeaconState) -> bool: return state.latest_execution_payload_header.block_hash == state.latest_block_hash ``` ### Beacon State accessors #### `get_ptc` ```python def get_ptc(state: BeaconState, slot: Slot) -> Vector[ValidatorIndex, PTC_SIZE]: """ Get the payload timeliness committee for the given ``slot`` """ epoch = compute_epoch_at_slot(slot) committees_per_slot = bit_floor(min(get_committee_count_per_slot(state, epoch), PTC_SIZE)) members_per_committee = PTC_SIZE // committees_per_slot validator_indices: List[ValidatorIndex] = [] for idx in range(committees_per_slot): beacon_committee = get_beacon_committee(state, slot, CommitteeIndex(idx)) validator_indices += beacon_committee[:members_per_committee] return validator_indices ``` #### Modified `get_attesting_indices` `get_attesting_indices` is modified to ignore PTC votes ```python def get_attesting_indices(state: BeaconState, attestation: Attestation) -> Set[ValidatorIndex]: """ Return the set of attesting indices corresponding to ``aggregation_bits`` and ``committee_bits``. """ output: Set[ValidatorIndex] = set() committee_indices = get_committee_indices(attestation.committee_bits) committee_offset = 0 for index in committee_indices: committee = get_beacon_committee(state, attestation.data.slot, index) committee_attesters = set( index for i, index in enumerate(committee) if attestation.aggregation_bits[committee_offset + i]) output = output.union(committee_attesters) committee_offset += len(committee) if compute_epoch_at_slot(attestation.data.slot) < EIP7732_FORK_EPOCH: return output ptc = get_ptc(state, attestation.data.slot) return set(i for i in output if i not in ptc) ``` #### `get_payload_attesting_indices` ```python def get_payload_attesting_indices(state: BeaconState, slot: Slot, payload_attestation: PayloadAttestation) -> Set[ValidatorIndex]: """ Return the set of attesting indices corresponding to ``payload_attestation``. """ ptc = get_ptc(state, slot) return set(index for i, index in enumerate(ptc) if payload_attestation.aggregation_bits[i]) ``` #### `get_indexed_payload_attestation` ```python def get_indexed_payload_attestation(state: BeaconState, slot: Slot, payload_attestation: PayloadAttestation) -> IndexedPayloadAttestation: """ Return the indexed payload attestation corresponding to ``payload_attestation``. """ attesting_indices = get_payload_attesting_indices(state, slot, payload_attestation) return IndexedPayloadAttestation( attesting_indices=sorted(attesting_indices), data=payload_attestation.data, signature=payload_attestation.signature, ) ``` ## Beacon chain state transition function *Note*: state transition is fundamentally modified in EIP-7732. The full state transition is broken in two parts, first importing a signed block and then importing an execution payload. The post-state corresponding to a pre-state `state` and a signed beacon block `signed_block` is defined as `state_transition(state, signed_block)`. State transitions that trigger an unhandled exception (e.g. a failed `assert` or an out-of-range list access) are considered invalid. State transitions that cause a `uint64` overflow or underflow are also considered invalid. The post-state corresponding to a pre-state `state` and a signed execution payload envelope `signed_envelope` is defined as `process_execution_payload(state, signed_envelope)`. State transitions that trigger an unhandled exception (e.g. a failed `assert` or an out-of-range list access) are considered invalid. State transitions that cause an `uint64` overflow or underflow are also considered invalid. ### Block processing ```python def process_block(state: BeaconState, block: BeaconBlock) -> None: process_block_header(state, block) process_withdrawals(state) # [Modified in EIP-7732] process_execution_payload_header(state, block) # [Modified in EIP-7732, removed process_execution_payload] process_randao(state, block.body) process_eth1_data(state, block.body) process_operations(state, block.body) # [Modified in EIP-7732] process_sync_aggregate(state, block.body.sync_aggregate) ``` #### Withdrawals ##### Modified `process_withdrawals` **Note:** This is modified to take only the `state` as parameter. Withdrawals are deterministic given the beacon state, any execution payload that has the corresponding block as parent beacon block is required to honor these withdrawals in the execution layer. This function must be called before `process_execution_payload_header` as this latter function affects validator balances. ```python def process_withdrawals(state: BeaconState) -> None: # return early if the parent block was empty if not is_parent_block_full(state): return withdrawals, partial_withdrawals_count = get_expected_withdrawals(state) state.latest_withdrawals_root = hash_tree_root(withdrawals) for withdrawal in withdrawals: decrease_balance(state, withdrawal.validator_index, withdrawal.amount) # Update pending partial withdrawals state.pending_partial_withdrawals = state.pending_partial_withdrawals[partial_withdrawals_count:] # Update the next withdrawal index if this block contained withdrawals if len(withdrawals) != 0: latest_withdrawal = withdrawals[-1] state.next_withdrawal_index = WithdrawalIndex(latest_withdrawal.index + 1) # Update the next validator index to start the next withdrawal sweep if len(withdrawals) == MAX_WITHDRAWALS_PER_PAYLOAD: # Next sweep starts after the latest withdrawal's validator index next_validator_index = ValidatorIndex((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 header ##### New `verify_execution_payload_header_signature` ```python def verify_execution_payload_header_signature(state: BeaconState, signed_header: SignedExecutionPayloadHeader) -> bool: # Check the signature builder = state.validators[signed_header.message.builder_index] signing_root = compute_signing_root(signed_header.message, get_domain(state, DOMAIN_BEACON_BUILDER)) return bls.Verify(builder.pubkey, signing_root, signed_header.signature) ``` ##### New `process_execution_payload_header` ```python def process_execution_payload_header(state: BeaconState, block: BeaconBlock) -> None: # Verify the header signature signed_header = block.body.signed_execution_payload_header assert verify_execution_payload_header_signature(state, signed_header) # Check that the builder has funds to cover the bid header = signed_header.message builder_index = header.builder_index amount = header.value assert state.balances[builder_index] >= amount # Verify that the bid is for the current slot assert header.slot == block.slot # Verify that the bid is for the right parent block assert header.parent_block_hash == state.latest_block_hash assert header.parent_block_root == block.parent_root # Transfer the funds from the builder to the proposer decrease_balance(state, builder_index, amount) increase_balance(state, block.proposer_index, amount) # Cache the signed execution payload header state.latest_execution_payload_header = header ``` #### Operations ##### Modified `process_operations` **Note:** `process_operations` is modified to process PTC attestations ```python def process_operations(state: BeaconState, body: BeaconBlockBody) -> None: # Verify that outstanding deposits are processed up to the maximum number of deposits assert len(body.deposits) == min(MAX_DEPOSITS, state.eth1_data.deposit_count - state.eth1_deposit_index) def for_ops(operations: Sequence[Any], fn: Callable[[BeaconState, Any], None]) -> None: for operation in operations: fn(state, operation) for_ops(body.proposer_slashings, process_proposer_slashing) for_ops(body.attester_slashings, process_attester_slashing) for_ops(body.attestations, process_attestation) for_ops(body.deposits, process_deposit) for_ops(body.voluntary_exits, process_voluntary_exit) for_ops(body.bls_to_execution_changes, process_bls_to_execution_change) # Removed `process_deposit_request` in EIP-7732 # Removed `process_withdrawal_request` in EIP-7732 # Removed `process_consolidation_request` in EIP-7732 for_ops(body.payload_attestations, process_payload_attestation) # [New in EIP-7732] ``` ##### Payload Attestations ###### `process_payload_attestation` ```python def process_payload_attestation(state: BeaconState, payload_attestation: PayloadAttestation) -> None: # Check that the attestation is for the parent beacon block data = payload_attestation.data assert data.beacon_block_root == state.latest_block_header.parent_root # Check that the attestation is for the previous slot assert data.slot + 1 == state.slot # Verify signature indexed_payload_attestation = get_indexed_payload_attestation(state, data.slot, payload_attestation) assert is_valid_indexed_payload_attestation(state, indexed_payload_attestation) if state.slot % SLOTS_PER_EPOCH == 0: epoch_participation = state.previous_epoch_participation else: epoch_participation = state.current_epoch_participation # Return early if the attestation is for the wrong payload status payload_was_present = data.slot == state.latest_full_slot voted_present = data.payload_status == PAYLOAD_PRESENT proposer_reward_denominator = (WEIGHT_DENOMINATOR - PROPOSER_WEIGHT) * WEIGHT_DENOMINATOR // PROPOSER_WEIGHT proposer_index = get_beacon_proposer_index(state) if voted_present != payload_was_present: # Unset the flags in case they were set by an equivocating ptc attestation proposer_penalty_numerator = 0 for index in indexed_payload_attestation.attesting_indices: for flag_index, weight in enumerate(PARTICIPATION_FLAG_WEIGHTS): if has_flag(epoch_participation[index], flag_index): epoch_participation[index] = remove_flag(epoch_participation[index], flag_index) proposer_penalty_numerator += get_base_reward(state, index) * weight # Penalize the proposer proposer_penalty = Gwei(2 * proposer_penalty_numerator // proposer_reward_denominator) decrease_balance(state, proposer_index, proposer_penalty) return # Reward the proposer and set all the participation flags in case of correct attestations proposer_reward_numerator = 0 for index in indexed_payload_attestation.attesting_indices: for flag_index, weight in enumerate(PARTICIPATION_FLAG_WEIGHTS): if 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 = Gwei(proposer_reward_numerator // proposer_reward_denominator) increase_balance(state, proposer_index, proposer_reward) ``` #### Modified `process_execution_payload` ##### New `verify_execution_payload_envelope_signature` ```python def verify_execution_payload_envelope_signature( state: BeaconState, signed_envelope: SignedExecutionPayloadEnvelope) -> bool: builder = state.validators[signed_envelope.message.builder_index] signing_root = compute_signing_root(signed_envelope.message, get_domain(state, DOMAIN_BEACON_BUILDER)) return bls.Verify(builder.pubkey, signing_root, signed_envelope.signature) ``` *Note*: `process_execution_payload` is now an independent check in state transition. It is called when importing a signed execution payload proposed by the builder of the current slot. ```python def process_execution_payload(state: BeaconState, signed_envelope: SignedExecutionPayloadEnvelope, execution_engine: ExecutionEngine, verify: bool = True) -> None: # Verify signature if verify: assert verify_execution_payload_envelope_signature(state, signed_envelope) envelope = signed_envelope.message payload = envelope.payload # Verify consistency with the beacon block assert envelope.beacon_block_root == hash_tree_root(state.latest_block_header) # Verify consistency with the committed header committed_header = state.latest_execution_payload_header assert envelope.builder_index == committed_header.builder_index assert committed_header.blob_kzg_commitments_root == hash_tree_root(envelope.blob_kzg_commitments) if not envelope.payload_withheld: # Verify the withdrawals root assert hash_tree_root(payload.withdrawals) == state.last_withdrawals_root # Verify the gas_limit assert committed_header.gas_limit == payload.gas_limit assert committed_header.block_hash == payload.block_hash # Verify consistency of the parent hash with respect to the previous execution payload assert payload.parent_hash == state.latest_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 the execution payload is valid versioned_hashes = [kzg_commitment_to_versioned_hash(commitment) for commitment in envelope.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, ) ) # Process Electra operations def for_ops(operations: Sequence[Any], fn: Callable[[BeaconState, Any], None]) -> None: for operation in operations: fn(state, operation) for_ops(payload.deposit_requests, process_deposit_request) for_ops(payload.withdrawal_requests, process_withdrawal_request) for_ops(payload, process_consolidation_request) # Cache the execution payload header and proposer state.latest_block_hash = payload.block_hash state.latest_full_slot = state.slot # Verify the state root if verify: assert envelope.state_root == hash_tree_root(state) ```