Separate type for unaggregated network attestations

specs/electra/beacon-chain.md

@@ -29,6 +29,7 @@
     - [`WithdrawalRequest`](#withdrawalrequest)
     - [`ConsolidationRequest`](#consolidationrequest)
     - [`PendingConsolidation`](#pendingconsolidation)
+    - [`SingleAttestation`](#singleattestation)
     - [`ExecutionRequests`](#executionrequests)
   - [Modified Containers](#modified-containers)
     - [`AttesterSlashing`](#attesterslashing)
@@ -257,6 +258,16 @@ class PendingConsolidation(Container):
     target_index: ValidatorIndex
 ```
 
+#### `SingleAttestation`
+
+```python
+class SingleAttestation(Container):
+    committee_index: CommitteeIndex
+    attester_index: ValidatorIndex
+    data: AttestationData
+    signature: BLSSignature
+```
+
 #### `ExecutionRequests`
 
 *Note*: This container holds requests from the execution layer that are received in [
@@ -945,7 +956,7 @@ def notify_new_payload(self: ExecutionEngine,
                        execution_requests: ExecutionRequests,
                        parent_beacon_block_root: Root) -> bool:
     """
-    Return ``True`` if and only if ``execution_payload`` and ``execution_requests`` 
+    Return ``True`` if and only if ``execution_payload`` and ``execution_requests``
     are valid with respect to ``self.execution_state``.
     """
     ...
@@ -974,8 +985,8 @@ def verify_and_notify_new_payload(self: ExecutionEngine,
 
     # [Modified in Electra]
     if not self.notify_new_payload(
-            execution_payload, 
-            execution_requests, 
+            execution_payload,
+            execution_requests,
             parent_beacon_block_root):
         return False
 

specs/electra/p2p-interface.md

@@ -54,9 +54,18 @@ The following validations are added:
 
 ##### `beacon_attestation_{subnet_id}`
 
-The following convenience variables are re-defined
-- `index = get_committee_indices(attestation.committee_bits)[0]`
+The topic is updated to propagate `SingleAttestation` objects.
+
+The following convenience variables are re-defined:
+- `index = attestation.committee_index`
 
 The following validations are added:
-* [REJECT] `len(committee_indices) == 1`, where `committee_indices = get_committee_indices(attestation)`.
-* [REJECT] `attestation.data.index == 0`
+- _[REJECT]_ `attestation.data.index == 0`
+- _[REJECT]_ The attester is a member of the committee -- i.e.
+  `atestation.attester_index in get_beacon_committee(state, attestation.data.slot, index)`.
+
+The following validations are removed:
+- _[REJECT]_ The attestation is unaggregated --
+  that is, it has exactly one participating validator (`len([bit for bit in aggregation_bits if bit]) == 1`, i.e. exactly 1 bit is set).
+- _[REJECT]_ The number of aggregation bits matches the committee size -- i.e.
+  `len(aggregation_bits) == len(get_beacon_committee(state, attestation.data.slot, index))`.

specs/electra/validator.md

@@ -152,16 +152,17 @@ def prepare_execution_payload(state: BeaconState,
 
 ### Construct attestation
 
-- Set `attestation_data.index = 0`.
-- Let `attestation.aggregation_bits` be a `Bitlist[MAX_VALIDATORS_PER_COMMITTEE * MAX_COMMITTEES_PER_SLOT]` of length `len(committee)`, where the bit of the index of the validator in the `committee` is set to `0b1`.
-- Let `attestation.committee_bits` be a `Bitvector[MAX_COMMITTEES_PER_SLOT]`, where the bit at the index associated with the validator's committee is set to `0b1`.
+The validator creates `attestation` as a `SingleAttestation` container
+with updated field assignments:
 
-*Note*: Calling `get_attesting_indices(state, attestation)` should return a list of length equal to 1, containing `validator_index`.
+- Set `attestation_data.index = 0`.
+- Set `attestation.committee_index` to the index associated with the validator's committee.
+- Set `attestation.attester_index` to the index of the validator.
 
 ## Attestation aggregation
 
 ### Construct aggregate
 
 - Set `attestation_data.index = 0`.
 - Let `aggregation_bits` be a `Bitlist[MAX_VALIDATORS_PER_COMMITTEE * MAX_COMMITTEES_PER_SLOT]` of length `len(committee)`, where each bit set from each individual attestation is set to `0b1`.
-- Set `attestation.committee_bits = committee_bits`, where `committee_bits` has the same value as in each individual attestation.
+- Set `attestation.committee_bits = committee_bits`, where `committee_bits` has the bit set corresponding to `committee_index` in each individual attestation.