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Add blob sidecar inclusion proof

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dapplion 2023-10-27 12:10:29 +03:00
parent 612d1485ba
commit 530efa88aa
2 changed files with 71 additions and 52 deletions
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79
specs/deneb/p2p-interface.md
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@ -14,10 +14,11 @@ The specification of these changes continues in the same format as the network s
- [Configuration](#configuration)
- [Containers](#containers)
- [`BlobSidecar`](#blobsidecar)
- [`SignedBlobSidecar`](#signedblobsidecar)
- [`BlobIdentifier`](#blobidentifier)
- [Helpers](#helpers)
- [`verify_blob_sidecar_signature`](#verify_blob_sidecar_signature)
- [`verify_blob_sidecar_inclusion_proof`](#verify_blob_sidecar_inclusion_proof)
- [`is_valid_merkle_path`](#is_valid_merkle_path)
- [The gossip domain: gossipsub](#the-gossip-domain-gossipsub)
- [Topics and messages](#topics-and-messages)
- [Global topics](#global-topics)
@ -51,6 +52,8 @@ The specification of these changes continues in the same format as the network s
| `MAX_REQUEST_BLOB_SIDECARS` | `MAX_REQUEST_BLOCKS_DENEB * MAX_BLOBS_PER_BLOCK` | Maximum number of blob sidecars in a single request |
| `MIN_EPOCHS_FOR_BLOB_SIDECARS_REQUESTS` | `2**12` (= 4096 epochs, ~18 days) | The minimum epoch range over which a node must serve blob sidecars |
| `BLOB_SIDECAR_SUBNET_COUNT` | `6` | The number of blob sidecar subnets used in the gossipsub protocol. |
| `KZG_COMMITMENT_INCLUSION_PROOF_DEPTH` | `17` | Merkle proof for `blob_kzg_commitments` list item |
| `BLOB_KZG_COMMITMENT_GINDEX` | `27` | Gindex path to `blob_kzg_commitments` on `BeaconBlockBody` container
### Containers
@ -60,24 +63,12 @@ The specification of these changes continues in the same format as the network s
```python
class BlobSidecar(Container):
block_root: Root
index: BlobIndex # Index of blob in block
slot: Slot
block_parent_root: Root # Proposer shuffling determinant
proposer_index: ValidatorIndex
blob: Blob
kzg_commitment: KZGCommitment
kzg_proof: KZGProof # Allows for quick verification of kzg_commitment
```
#### `SignedBlobSidecar`
*[New in Deneb:EIP4844]*
```python
class SignedBlobSidecar(Container):
message: BlobSidecar
signature: BLSSignature
commitment_inclusion_proof: [Bytes32, KZG_COMMITMENT_INCLUSION_PROOF_DEPTH]
signed_block_header: SignedBeaconBlockHeader
```
#### `BlobIdentifier`
@ -95,10 +86,39 @@ class BlobIdentifier(Container):
##### `verify_blob_sidecar_signature`
```python
def verify_blob_sidecar_signature(state: BeaconState, signed_blob_sidecar: SignedBlobSidecar) -> bool:
proposer = state.validators[signed_blob_sidecar.message.proposer_index]
signing_root = compute_signing_root(signed_blob_sidecar.message, get_domain(state, DOMAIN_BLOB_SIDECAR))
return bls.Verify(proposer.pubkey, signing_root, signed_blob_sidecar.signature)
def verify_blob_sidecar_signature(state: BeaconState, blob_sidecar: BlobSidecar) -> bool:
block_header = blob_sidecar.signed_block_header.message
proposer = state.validators[block_header.proposer_index]
domain = get_domain(state, DOMAIN_BEACON_PROPOSER, compute_epoch_at_slot(block_header.slot))
signing_root = compute_signing_root(block_header, domain)
return bls.Verify(proposer.pubkey, signing_root, blob_sidecar.signed_block_header.signature)
```
##### `verify_blob_sidecar_inclusion_proof`
```python
def verify_blob_sidecar_inclusion_proof(blob_sidecar: BlobSidecar) -> bool:
commitment_item_gindex = MAX_BLOB_COMMITMENTS_PER_BLOCK + blob_sidecar.index
gindex = BLOB_KZG_COMMITMENT_GINDEX + commitment_item_gindex << floorlog2(BLOB_ZKG_COMMITMENT_GINDEX)
return is_valid_merkle_path(
leaf=blob_sidecar.kzg_commitment.hash_tree_root(),
branch=blob_sidecar.commitment_inclusion_proof,
gindex=gindex,
root=blob_sidecar.signed_block_header.message.body_root,
)
```
#### `is_valid_merkle_path`
```python
def is_valid_merkle_path(leaf: Bytes32, branch: Sequence[Bytes32], gindex: int, root: Root) -> bool:
value = leaf
for i in range(len(branch)):
if (gindex >> i) & 1 == 0:
value = hash(branch[i] + value)
else:
value = hash(value + branch[i])
return value == root
```
### The gossip domain: gossipsub
@ -123,7 +143,7 @@ The new topics along with the type of the `data` field of a gossipsub message ar
| Name | Message Type |
| - | - |
| `blob_sidecar_{subnet_id}` | `SignedBlobSidecar` [New in Deneb:EIP4844] |
| `blob_sidecar_{subnet_id}` | `BlobSidecar` [New in Deneb:EIP4844] |
##### Global topics
@ -146,18 +166,19 @@ New validation:
This topic is used to propagate signed blob sidecars, where each blob index maps to some `subnet_id`.
The following validations MUST pass before forwarding the `signed_blob_sidecar` on the network, assuming the alias `sidecar = signed_blob_sidecar.message`:
The following validations MUST pass before forwarding the `blob_sidecar` on the network, assuming the alias `sidecar = blob_sidecar` and `block_header = blob_sidecar.signed_block_header.message`:
- _[REJECT]_ The sidecar's index is consistent with `MAX_BLOBS_PER_BLOCK` -- i.e. `sidecar.index < MAX_BLOBS_PER_BLOCK`.
- _[REJECT]_ The sidecar is for the correct subnet -- i.e. `compute_subnet_for_blob_sidecar(sidecar.index) == subnet_id`.
- _[IGNORE]_ The sidecar is not from a future slot (with a `MAXIMUM_GOSSIP_CLOCK_DISPARITY` allowance) -- i.e. validate that `sidecar.slot <= current_slot` (a client MAY queue future sidecars for processing at the appropriate slot).
- _[IGNORE]_ The sidecar is from a slot greater than the latest finalized slot -- i.e. validate that `sidecar.slot > compute_start_slot_at_epoch(state.finalized_checkpoint.epoch)`
- _[IGNORE]_ The sidecar's block's parent (defined by `sidecar.block_parent_root`) has been seen (via both gossip and non-gossip sources) (a client MAY queue sidecars for processing once the parent block is retrieved).
- _[REJECT]_ The sidecar's block's parent (defined by `sidecar.block_parent_root`) passes validation.
- _[REJECT]_ The sidecar is from a higher slot than the sidecar's block's parent (defined by `sidecar.block_parent_root`).
- _[REJECT]_ The proposer signature, `signed_blob_sidecar.signature`, is valid as verified by `verify_blob_sidecar_signature`.
- _[IGNORE]_ The sidecar is the only sidecar with valid signature received for the tuple `(sidecar.block_root, sidecar.index)`.
- _[REJECT]_ The sidecar is proposed by the expected `proposer_index` for the block's slot in the context of the current shuffling (defined by `block_parent_root`/`slot`).
- _[IGNORE]_ The sidecar is not from a future slot (with a `MAXIMUM_GOSSIP_CLOCK_DISPARITY` allowance) -- i.e. validate that `block_header.slot <= current_slot` (a client MAY queue future sidecars for processing at the appropriate slot).
- _[IGNORE]_ The sidecar is from a slot greater than the latest finalized slot -- i.e. validate that `block_header.slot > compute_start_slot_at_epoch(state.finalized_checkpoint.epoch)`
- _[IGNORE]_ The sidecar's block's parent (defined by `block_header.parent_root`) has been seen (via both gossip and non-gossip sources) (a client MAY queue sidecars for processing once the parent block is retrieved).
- _[REJECT]_ The sidecar's block's parent (defined by `block_header.parent_root`) passes validation.
- _[REJECT]_ The sidecar is from a higher slot than the sidecar's block's parent (defined by `block_header.parent_root`).
- _[REJECT]_ The proposer signature in `blob_sidecar.signed_block_header`, is valid as verified by `verify_blob_sidecar_signature`.
- _[REJECT]_ The sidecar's inclusion proof is valid as verified by `verify_blob_sidecar_inclusion_proof`.
- _[IGNORE]_ The sidecar is the only sidecar with valid signature received for the tuple `(hash_tree_root(block_header), sidecar.index)`.
- _[REJECT]_ The sidecar is proposed by the expected `proposer_index` for the block's slot in the context of the current shuffling (defined by `parent_root`/`slot`).
If the `proposer_index` cannot immediately be verified against the expected shuffling, the sidecar MAY be queued for later processing while proposers for the block's branch are calculated -- in such a case _do not_ `REJECT`, instead `IGNORE` this message.
###### `beacon_aggregate_and_proof`

44
specs/deneb/validator.md
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@ -21,8 +21,8 @@
- [Constructing the `BeaconBlockBody`](#constructing-the-beaconblockbody)
- [ExecutionPayload](#executionpayload)
- [Blob KZG commitments](#blob-kzg-commitments)
- [Constructing the `SignedBlobSidecar`s](#constructing-the-signedblobsidecars)
- [Sidecar](#sidecar)
- [Constructing the `BlobSidecar`s](#constructing-the-blobsidecars)
- [BlobSidecar](#blob-sidecar)
<!-- END doctoc generated TOC please keep comment here to allow auto update -->
<!-- /TOC -->
@ -133,49 +133,47 @@ use the `payload_id` to retrieve `blobs`, `blob_kzg_commitments`, and `blob_kzg_
via `get_payload(payload_id).blobs_bundle`.
2. Set `block.body.blob_kzg_commitments = blob_kzg_commitments`.
#### Constructing the `SignedBlobSidecar`s
#### Constructing the `BlobSidecar`s
*[New in Deneb:EIP4844]*
To construct a `SignedBlobSidecar`, a `signed_blob_sidecar` is defined with the necessary context for block and sidecar proposal.
To construct a `BlobSidecar`, a `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.
Blobs associated with a block are packaged into sidecar objects for distribution to the associated sidecar topic, the `blob_sidecar_{subnet_id}` pubsub topic.
Each `sidecar` is obtained from:
```python
def get_blob_sidecars(block: BeaconBlock,
def get_blob_sidecars(signed_block: SignedBeaconBlock,
blobs: Sequence[Blob],
blob_kzg_proofs: Sequence[KZGProof]) -> Sequence[BlobSidecar]:
block_header = BeaconBlockHeader(
slot=block.slot,
proposer_index=block.proposer_index,
parent_root=block.parent_root,
state_root=Bytes32(), # Overwritten in the next process_slot call
body_root=hash_tree_root(block.body),
)
signed_block_header = SignedBeaconBlockHeader(message=block_header, signature=signed_block.signature)
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_commitment=signed_block.message.body.blob_kzg_commitments[index],
kzg_proof=blob_kzg_proofs[index],
commitment_inclusion_proof=compute_commitment_inclusion_proof(
signed_block.message.body,
signed_block.message.body.blob_kzg_commitments[index],
index,
),
signed_block_header=signed_block_header,
)
for index, blob in enumerate(blobs)
]
```
Then for each sidecar, `signed_sidecar = SignedBlobSidecar(message=sidecar, signature=signature)` is constructed and published to the associated sidecar topic, the `blob_sidecar_{subnet_id}` pubsub topic.
`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)
```
The `subnet_id` for the `signed_sidecar` is calculated with:
- Let `blob_index = signed_sidecar.message.index`.
- Let `subnet_id = compute_subnet_for_blob_sidecar(blob_index)`.