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Gloas -- Networking

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

Introduction

This document contains the consensus-layer networking specifications for Gloas.

The specification of these changes continues in the same format as the network specifications of previous upgrades, and assumes them as pre-requisite.

Modification in Gloas

Configuration

Name Value Description
MAX_REQUEST_PAYLOADS 2**7 (= 128) Maximum number of execution payload envelopes in a single request

Containers

Modified DataColumnSidecar

Note: The signed_block_header, kzg_commitments, and kzg_commitments_inclusion_proof fields have been removed from DataColumnSidecar in Gloas as header and inclusion proof verifications are no longer required in Gloas. The KZG commitments are now located at block.body.signed_execution_payload_bid.message.blob_kzg_commitments where block is the BeaconBlock associated with beacon_block_root.

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class DataColumnSidecar(Container):
    index: ColumnIndex
    column: List[Cell, MAX_BLOB_COMMITMENTS_PER_BLOCK]
    # [Modified in Gloas:EIP7732]
    # Removed `kzg_commitments`
    kzg_proofs: List[KZGProof, MAX_BLOB_COMMITMENTS_PER_BLOCK]
    # [Modified in Gloas:EIP7732]
    # Removed `signed_block_header`
    # [Modified in Gloas:EIP7732]
    # Removed `kzg_commitments_inclusion_proof`
    # [New in Gloas:EIP7732]
    slot: Slot
    # [New in Gloas:EIP7732]
    beacon_block_root: Root

New ProposerPreferences

[New in Gloas:EIP7732]

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class ProposerPreferences(Container):
    proposal_slot: Slot
    validator_index: ValidatorIndex
    fee_recipient: ExecutionAddress
    gas_limit: uint64

New SignedProposerPreferences

[New in Gloas:EIP7732]

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class SignedProposerPreferences(Container):
    message: ProposerPreferences
    signature: BLSSignature

Helpers

Modified compute_fork_version

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def compute_fork_version(epoch: Epoch) -> Version:
    """
    Return the fork version at the given ``epoch``.
    """
    if epoch >= GLOAS_FORK_EPOCH:
        return GLOAS_FORK_VERSION
    if epoch >= FULU_FORK_EPOCH:
        return FULU_FORK_VERSION
    if epoch >= ELECTRA_FORK_EPOCH:
        return ELECTRA_FORK_VERSION
    if epoch >= DENEB_FORK_EPOCH:
        return DENEB_FORK_VERSION
    if epoch >= CAPELLA_FORK_EPOCH:
        return CAPELLA_FORK_VERSION
    if epoch >= BELLATRIX_FORK_EPOCH:
        return BELLATRIX_FORK_VERSION
    if epoch >= ALTAIR_FORK_EPOCH:
        return ALTAIR_FORK_VERSION
    return GENESIS_FORK_VERSION

Modified verify_data_column_sidecar_kzg_proofs

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def verify_data_column_sidecar_kzg_proofs(
    sidecar: DataColumnSidecar,
    # [New in Gloas:EIP7732]
    kzg_commitments: List[KZGCommitment, MAX_BLOB_COMMITMENTS_PER_BLOCK],
) -> bool:
    """
    Verify if the KZG proofs are correct.
    """
    # The column index also represents the cell index
    cell_indices = [CellIndex(sidecar.index)] * len(sidecar.column)

    # Batch verify that the cells match the corresponding commitments and proofs
    return verify_cell_kzg_proof_batch(
        # [Modified in Gloas:EIP7732]
        commitments_bytes=kzg_commitments,
        cell_indices=cell_indices,
        cells=sidecar.column,
        proofs_bytes=sidecar.kzg_proofs,
    )

Modified verify_data_column_sidecar

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def verify_data_column_sidecar(
    sidecar: DataColumnSidecar,
    # [New in Gloas:EIP7732]
    kzg_commitments: List[KZGCommitment, MAX_BLOB_COMMITMENTS_PER_BLOCK],
) -> bool:
    """
    Verify if the data column sidecar is valid.
    """
    # The sidecar index must be within the valid range
    if sidecar.index >= NUMBER_OF_COLUMNS:
        return False

    # [Modified in Gloas:EIP7732]
    # A sidecar for zero blobs is invalid
    if len(sidecar.column) == 0:
        return False

    # [Modified in Gloas:EIP7732]
    # The column length must be equal to the number of commitments/proofs
    if len(sidecar.column) != len(kzg_commitments) or len(sidecar.column) != len(
        sidecar.kzg_proofs
    ):
        return False

    return True

The gossip domain: gossipsub

Some gossip meshes are upgraded in Gloas to support upgraded types.

Topics and messages

Topics follow the same specification as in prior upgrades.

The beacon_block topic is updated to support the modified type

Name Message Type
beacon_block SignedBeaconBlock

The new topics along with the type of the data field of a gossipsub message are given in this table:

Name Message Type
execution_payload_bid SignedExecutionPayloadBid
execution_payload SignedExecutionPayloadEnvelope
payload_attestation_message PayloadAttestationMessage
proposer_preferences SignedProposerPreferences
Global topics

Gloas introduces new global topics for execution bid, execution payload and payload attestation.

beacon_aggregate_and_proof

Let block be the beacon block corresponding to aggregate.data.beacon_block_root.

The following validations are added:

  • [REJECT] aggregate.data.index < 2.
  • [REJECT] aggregate.data.index == 0 if block.slot == aggregate.data.slot.

The following validations are removed:

  • [REJECT] aggregate.data.index == 0.
beacon_block

[Modified in Gloas:EIP7732]

The type of the payload of this topic changes to the (modified) SignedBeaconBlock found in the beacon-chain changes.

There are no new validations for this topic. However, all validations with regards to the ExecutionPayload are removed:

  • [REJECT] The length of KZG commitments is less than or equal to the limitation defined in the consensus layer -- i.e. validate that len(signed_beacon_block.message.body.blob_kzg_commitments) <= get_blob_parameters(get_current_epoch(state)).max_blobs_per_block
  • [REJECT] The block's execution payload timestamp is correct with respect to the slot -- i.e. execution_payload.timestamp == compute_time_at_slot(state, block.slot).
  • If execution_payload verification of block's parent by an execution node is not complete:
  • [REJECT] The block's parent (defined by block.parent_root) passes all validation (excluding execution node verification of the block.body.execution_payload).
  • otherwise:
  • [IGNORE] The block's parent (defined by block.parent_root) passes all validation (including execution node verification of the block.body.execution_payload).

And instead the following validations are set in place with the alias bid = signed_execution_payload_bid.message:

  • [REJECT] The length of KZG commitments is less than or equal to the limitation defined in the consensus layer -- i.e. validate that len(bid.blob_kzg_commitments) <= get_blob_parameters(get_current_epoch(state)).max_blobs_per_block
  • If execution_payload verification of block's execution payload parent by an execution node is complete:
  • [REJECT] The block's execution payload parent (defined by bid.parent_block_hash) passes all validation.
  • [REJECT] The bid's parent (defined by bid.parent_block_root) equals the block's parent (defined by block.parent_root).
execution_payload

This topic is used to propagate execution payload messages as SignedExecutionPayloadEnvelope.

The following validations MUST pass before forwarding the signed_execution_payload_envelope on the network, assuming the alias envelope = signed_execution_payload_envelope.message, payload = envelope.payload:

  • [IGNORE] The envelope's block root envelope.block_root has been seen (via gossip or non-gossip sources) (a client MAY queue payload for processing once the block is retrieved).
  • [IGNORE] The node has not seen another valid SignedExecutionPayloadEnvelope for this block root from this builder.
  • [IGNORE] The envelope is from a slot greater than or equal to the latest finalized slot -- i.e. validate that envelope.slot >= compute_start_slot_at_epoch(store.finalized_checkpoint.epoch)

Let block be the block with envelope.beacon_block_root. Let bid alias block.body.signed_execution_payload_bid.message (notice that this can be obtained from the state.latest_execution_payload_bid)

  • [REJECT] block passes validation.
  • [REJECT] block.slot equals envelope.slot.
  • [REJECT] envelope.builder_index == bid.builder_index
  • [REJECT] payload.block_hash == bid.block_hash
  • [REJECT] signed_execution_payload_envelope.signature is valid with respect to the builder's public key.
payload_attestation_message

This topic is used to propagate signed payload attestation message.

The following validations MUST pass before forwarding the payload_attestation_message on the network, assuming the alias data = payload_attestation_message.data:

  • [IGNORE] The message's slot is for the current slot (with a MAXIMUM_GOSSIP_CLOCK_DISPARITY allowance), i.e. data.slot == current_slot.
  • [IGNORE] The payload_attestation_message is the first valid message received from the validator with index payload_attestation_message.validator_index.
  • [IGNORE] The message's block data.beacon_block_root has been seen (via gossip or non-gossip sources) (a client MAY queue attestation for processing once the block is retrieved. Note a client might want to request payload after).
  • [REJECT] The message's block data.beacon_block_root passes validation.
  • [REJECT] The message's validator index is within the payload committee in get_ptc(state, data.slot). The state is the head state corresponding to processing the block up to the current slot as determined by the fork choice.
  • [REJECT] payload_attestation_message.signature is valid with respect to the validator's public key.
execution_payload_bid

This topic is used to propagate signed bids as SignedExecutionPayloadBid.

The following validations MUST pass before forwarding the signed_execution_payload_bid on the network, assuming the alias bid = signed_execution_payload_bid.message:

  • [IGNORE] bid.slot is the current slot or the next slot.
  • [IGNORE] the SignedProposerPreferences where preferences.proposal_slot is equal to bid.slot has been seen.
  • [REJECT] bid.builder_index is a valid/active builder index -- i.e. is_active_builder(state, bid.builder_index) returns True.
  • [REJECT] bid.execution_payment is zero.
  • [REJECT] bid.fee_recipient matches the fee_recipient from the proposer's SignedProposerPreferences associated with bid.slot.
  • [REJECT] bid.gas_limit matches the gas_limit from the proposer's SignedProposerPreferences associated with bid.slot.
  • [IGNORE] this is the first signed bid seen with a valid signature from the given builder for this slot.
  • [IGNORE] this bid is the highest value bid seen for the corresponding slot and the given parent block hash.
  • [IGNORE] bid.value is less or equal than the builder's excess balance -- i.e. can_builder_cover_bid(state, builder_index, amount) returns True.
  • [IGNORE] bid.parent_block_hash is the block hash of a known execution payload in fork choice.
  • [IGNORE] bid.parent_block_root is the hash tree root of a known beacon block in fork choice.
  • [REJECT] signed_execution_payload_bid.signature is valid with respect to the bid.builder_index.

Note: Implementations SHOULD include DoS prevention measures to mitigate spam from malicious builders submitting numerous bids with minimal value increments. Possible strategies include: (1) only forwarding bids that exceed the current highest bid by a minimum threshold, or (2) forwarding only the highest observed bid at regular time intervals.

proposer_preferences

[New in Gloas:EIP7732]

This topic is used to propagate signed proposer preferences as SignedProposerPreferences. These messages allow validators to communicate their preferred fee_recipient and gas_limit to builders.

The following validations MUST pass before forwarding the signed_proposer_preferences on the network, assuming the alias preferences = signed_proposer_preferences.message:

  • [IGNORE] preferences.proposal_slot is in the next epoch -- i.e. compute_epoch_at_slot(preferences.proposal_slot) == get_current_epoch(state) + 1.
  • [REJECT] preferences.validator_index is present at the correct slot in the next epoch's portion of state.proposer_lookahead -- i.e. is_valid_proposal_slot(state, preferences) returns True.
  • [IGNORE] The signed_proposer_preferences is the first valid message received from the validator with index preferences.validator_index and the given slot preferences.slot.
  • [REJECT] signed_proposer_preferences.signature is valid with respect to the validator's public key.
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def is_valid_proposal_slot(state: BeaconState, preferences: ProposerPreferences) -> bool:
    """
    Check if the validator is the proposer for the given slot in the next epoch.
    """
    index = SLOTS_PER_EPOCH + preferences.proposal_slot % SLOTS_PER_EPOCH
    return state.proposer_lookahead[index] == preferences.validator_index
Blob subnets
data_column_sidecar_{subnet_id}

[Modified in Gloas:EIP7732]

The following validations MUST pass before forwarding the sidecar: DataColumnSidecar on the network, assuming the alias bid = block.body.signed_execution_payload_bid.message where block is the BeaconBlock associated with sidecar.beacon_block_root:

  • [IGNORE] A valid block for the sidecar's slot has been seen (via gossip or non-gossip sources). If not yet seen, a client MUST queue the sidecar for deferred validation and possible processing once the block is received or retrieved.
  • [REJECT] The sidecar's slot matches the slot of the block with root beacon_block_root.
  • [REJECT] The sidecar is valid as verified by verify_data_column_sidecar(sidecar, bid.blob_kzg_commitments).
  • [REJECT] The sidecar is for the correct subnet -- i.e. compute_subnet_for_data_column_sidecar(sidecar.index) == subnet_id.
  • [REJECT] The sidecar's column data is valid as verified by verify_data_column_sidecar_kzg_proofs(sidecar, bid.blob_kzg_commitments).
  • [IGNORE] The sidecar is the first sidecar for the tuple (sidecar.beacon_block_root, sidecar.index) with valid kzg proof.

Note: If the sidecar fails deferred validation, its forwarding peers MUST be downscored retroactively. If validation succeeds, the client MUST re-broadcast the sidecar.

Attestation subnets
beacon_attestation_{subnet_id}

Let block be the beacon block corresponding to attestation.data.beacon_block_root.

The following validations are added:

  • [REJECT] attestation.data.index < 2.
  • [REJECT] attestation.data.index == 0 if block.slot == attestation.data.slot.

The following validations are removed:

  • [REJECT] attestation.data.index == 0.

The Req/Resp domain

Messages

BeaconBlocksByRange v2

Protocol ID: /eth2/beacon_chain/req/beacon_blocks_by_range/2/

fork_version Chunk SSZ type
GENESIS_FORK_VERSION phase0.SignedBeaconBlock
ALTAIR_FORK_VERSION altair.SignedBeaconBlock
BELLATRIX_FORK_VERSION bellatrix.SignedBeaconBlock
CAPELLA_FORK_VERSION capella.SignedBeaconBlock
DENEB_FORK_VERSION deneb.SignedBeaconBlock
ELECTRA_FORK_VERSION electra.SignedBeaconBlock
FULU_FORK_VERSION fulu.SignedBeaconBlock
GLOAS_FORK_VERSION gloas.SignedBeaconBlock
BeaconBlocksByRoot v2

Protocol ID: /eth2/beacon_chain/req/beacon_blocks_by_root/2/

fork_version Chunk SSZ type
GENESIS_FORK_VERSION phase0.SignedBeaconBlock
ALTAIR_FORK_VERSION altair.SignedBeaconBlock
BELLATRIX_FORK_VERSION bellatrix.SignedBeaconBlock
CAPELLA_FORK_VERSION capella.SignedBeaconBlock
DENEB_FORK_VERSION deneb.SignedBeaconBlock
ELECTRA_FORK_VERSION electra.SignedBeaconBlock
FULU_FORK_VERSION fulu.SignedBeaconBlock
GLOAS_FORK_VERSION gloas.SignedBeaconBlock
ExecutionPayloadEnvelopesByRange v1

Protocol ID: /eth2/beacon_chain/req/execution_payload_envelopes_by_range/1/

Request Content:

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(
  start_slot: Slot
  count: uint64
)

Response Content:

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(
  List[SignedExecutionPayloadEnvelope, MAX_REQUEST_BLOCKS_DENEB]
)

Specifications of req\response methods are equivalent to BeaconBlocksByRange v2, with the only difference being the response content type.

For each successful response_chunk, the ForkDigest context epoch is determined by compute_epoch_at_slot(beacon_block.slot) based on the beacon_block referred to by signed_execution_payload_envelope.message.beacon_block_root.

Per fork_version = compute_fork_version(epoch):

fork_version Chunk SSZ type
GLOAS_FORK_VERSION gloas.SignedExecutionPayloadEnvelope
ExecutionPayloadEnvelopesByRoot v1

Protocol ID: /eth2/beacon_chain/req/execution_payload_envelopes_by_root/1/

For each successful response_chunk, the ForkDigest context epoch is determined by compute_epoch_at_slot(beacon_block.slot) based on the beacon_block referred to by signed_execution_payload_envelope.message.beacon_block_root.

Per fork_version = compute_fork_version(epoch):

fork_version Chunk SSZ type
GLOAS_FORK_VERSION gloas.SignedExecutionPayloadEnvelope

Request Content:

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(
  List[Root, MAX_REQUEST_PAYLOADS]
)

Response Content:

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(
  List[SignedExecutionPayloadEnvelope, MAX_REQUEST_PAYLOADS]
)

Requests execution payload envelopes by signed_execution_payload_envelope.message.block_root. The response is a list of SignedExecutionPayloadEnvelope whose length is less than or equal to the number of requested execution payload envelopes. It may be less in the case that the responding peer is missing payload envelopes.

No more than MAX_REQUEST_PAYLOADS may be requested at a time.

ExecutionPayloadEnvelopesByRoot is primarily used to recover recent execution payload envelopes (e.g. when receiving a payload attestation with revealed status as true but never received a payload).

The request MUST be encoded as an SSZ-field.

The response MUST consist of zero or more response_chunk. Each successful response_chunk MUST contain a single SignedExecutionPayloadEnvelope payload.

Clients MUST support requesting payload envelopes since the latest finalized epoch.

Clients MUST respond with at least one payload envelope, if they have it. Clients MAY limit the number of payload envelopes in the response.