158 lines
5.7 KiB
Markdown
158 lines
5.7 KiB
Markdown
# Deneb -- Honest Validator
|
|
|
|
**Notice**: This document is a work-in-progress for researchers and implementers.
|
|
|
|
## Table of contents
|
|
|
|
<!-- TOC -->
|
|
<!-- START doctoc generated TOC please keep comment here to allow auto update -->
|
|
<!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
|
|
|
|
- [Introduction](#introduction)
|
|
- [Prerequisites](#prerequisites)
|
|
- [Helpers](#helpers)
|
|
- [`BlobsBundle`](#blobsbundle)
|
|
- [Modified `GetPayloadResponse`](#modified-getpayloadresponse)
|
|
- [Protocol](#protocol)
|
|
- [`ExecutionEngine`](#executionengine)
|
|
- [Modified `get_payload`](#modified-get_payload)
|
|
- [Beacon chain responsibilities](#beacon-chain-responsibilities)
|
|
- [Block and sidecar proposal](#block-and-sidecar-proposal)
|
|
- [Constructing the `BeaconBlockBody`](#constructing-the-beaconblockbody)
|
|
- [Blob KZG commitments](#blob-kzg-commitments)
|
|
- [Constructing the `SignedBlobSidecar`s](#constructing-the-signedblobsidecars)
|
|
- [Sidecar](#sidecar)
|
|
|
|
<!-- END doctoc generated TOC please keep comment here to allow auto update -->
|
|
<!-- /TOC -->
|
|
|
|
## Introduction
|
|
|
|
This document represents the changes to be made in the code of an "honest validator" to implement Deneb.
|
|
|
|
## Prerequisites
|
|
|
|
This document is an extension of the [Capella -- Honest Validator](../capella/validator.md) guide.
|
|
All behaviors and definitions defined in this document, and documents it extends, carry over unless explicitly noted or overridden.
|
|
|
|
All terminology, constants, functions, and protocol mechanics defined in the updated [Beacon Chain doc of Deneb](./beacon-chain.md) are requisite for this document and used throughout.
|
|
Please see related Beacon Chain doc before continuing and use them as a reference throughout.
|
|
|
|
## Helpers
|
|
|
|
### `BlobsBundle`
|
|
|
|
```python
|
|
@dataclass
|
|
class BlobsBundle(object):
|
|
commitments: Sequence[KZGCommitment]
|
|
proofs: Sequence[KZGProof]
|
|
blobs: Sequence[Blob]
|
|
```
|
|
|
|
### Modified `GetPayloadResponse`
|
|
|
|
```python
|
|
@dataclass
|
|
class GetPayloadResponse(object):
|
|
execution_payload: ExecutionPayload
|
|
block_value: uint256
|
|
blobs_bundle: BlobsBundle
|
|
```
|
|
|
|
## Protocol
|
|
|
|
### `ExecutionEngine`
|
|
|
|
#### Modified `get_payload`
|
|
|
|
Given the `payload_id`, `get_payload` returns the most recent version of the execution payload that
|
|
has been built since the corresponding call to `notify_forkchoice_updated` method.
|
|
|
|
```python
|
|
def get_payload(self: ExecutionEngine, payload_id: PayloadId) -> GetPayloadResponse:
|
|
"""
|
|
Return ExecutionPayload, uint256, BlobsBundle objects.
|
|
"""
|
|
# pylint: disable=unused-argument
|
|
...
|
|
```
|
|
|
|
## Beacon chain responsibilities
|
|
|
|
All validator responsibilities remain unchanged other than those noted below.
|
|
|
|
### Block and sidecar proposal
|
|
|
|
#### Constructing the `BeaconBlockBody`
|
|
|
|
##### Blob KZG commitments
|
|
|
|
1. After retrieving the execution payload from the execution engine as specified in Capella,
|
|
use the `payload_id` to retrieve `blobs`, `blob_kzg_commitments`, and `blob_kzg_proofs`
|
|
via `get_payload(payload_id).blobs_bundle`.
|
|
2. Validate `blobs` and `blob_kzg_commitments`:
|
|
|
|
```python
|
|
def validate_blobs_and_kzg_commitments(execution_payload: ExecutionPayload,
|
|
blobs: Sequence[Blob],
|
|
blob_kzg_commitments: Sequence[KZGCommitment],
|
|
blob_kzg_proofs: Sequence[KZGProof]) -> None:
|
|
# Optionally sanity-check that the KZG commitments match the versioned hashes in the transactions
|
|
assert verify_kzg_commitments_against_transactions(execution_payload.transactions, blob_kzg_commitments)
|
|
|
|
# Optionally sanity-check that the KZG commitments match the blobs (as produced by the execution engine)
|
|
assert len(blob_kzg_commitments) == len(blobs) == len(blob_kzg_proofs)
|
|
assert verify_blob_kzg_proof_batch(blobs, blob_kzg_commitments, blob_kzg_proofs)
|
|
```
|
|
|
|
3. If valid, set `block.body.blob_kzg_commitments = blob_kzg_commitments`.
|
|
|
|
#### Constructing the `SignedBlobSidecar`s
|
|
|
|
To construct a `SignedBlobSidecar`, a `signed_blob_sidecar` is defined with the necessary context for block and sidecar proposal.
|
|
|
|
##### Sidecar
|
|
|
|
Blobs associated with a block are packaged into sidecar objects for distribution to the network.
|
|
|
|
Each `sidecar` is obtained from:
|
|
```python
|
|
def get_blob_sidecars(block: BeaconBlock,
|
|
blobs: Sequence[Blob],
|
|
blob_kzg_proofs: Sequence[KZGProof]) -> Sequence[BlobSidecar]:
|
|
return [
|
|
BlobSidecar(
|
|
block_root=hash_tree_root(block),
|
|
index=index,
|
|
slot=block.slot,
|
|
block_parent_root=block.parent_root,
|
|
blob=blob,
|
|
kzg_commitment=block.body.blob_kzg_commitments[index],
|
|
kzg_proof=blob_kzg_proofs[index],
|
|
)
|
|
for index, blob in enumerate(blobs)
|
|
]
|
|
|
|
```
|
|
|
|
Then for each sidecar, `signed_sidecar = SignedBlobSidecar(message=sidecar, signature=signature)` is constructed and published to the `blob_sidecar_{index}` topics according to its index.
|
|
|
|
`signature` is obtained from:
|
|
|
|
```python
|
|
def get_blob_sidecar_signature(state: BeaconState,
|
|
sidecar: BlobSidecar,
|
|
privkey: int) -> BLSSignature:
|
|
domain = get_domain(state, DOMAIN_BLOB_SIDECAR, compute_epoch_at_slot(sidecar.slot))
|
|
signing_root = compute_signing_root(sidecar, domain)
|
|
return bls.Sign(privkey, signing_root)
|
|
```
|
|
|
|
After publishing the peers on the network may request the sidecar through sync-requests, or a local user may be interested.
|
|
|
|
The validator MUST hold on to sidecars for `MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS` epochs and serve when capable,
|
|
to ensure the data-availability of these blobs throughout the network.
|
|
|
|
After `MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS` nodes MAY prune the sidecars and/or stop serving them.
|