Add payload attestation validator duty (#9178)

Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>

Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>

validator_client/lighthouse_validator_store/src/lib.rs

@@ -21,11 +21,12 @@ use tracing::{Instrument, debug, error, info, info_span, instrument, warn};
 use types::{
     AbstractExecPayload, Address, AggregateAndProof, Attestation, BeaconBlock, BlindedPayload,
     ChainSpec, ContributionAndProof, Domain, Epoch, EthSpec, ExecutionPayloadEnvelope, Fork,
-    FullPayload, Graffiti, Hash256, SelectionProof, SignedAggregateAndProof, SignedBeaconBlock,
-    SignedContributionAndProof, SignedExecutionPayloadEnvelope, SignedRoot,
-    SignedValidatorRegistrationData, SignedVoluntaryExit, Slot, SyncAggregatorSelectionData,
-    SyncCommitteeContribution, SyncCommitteeMessage, SyncSelectionProof, SyncSubnetId,
-    ValidatorRegistrationData, VoluntaryExit, graffiti::GraffitiString,
+    FullPayload, Graffiti, Hash256, PayloadAttestationData, PayloadAttestationMessage,
+    SelectionProof, SignedAggregateAndProof, SignedBeaconBlock, SignedContributionAndProof,
+    SignedExecutionPayloadEnvelope, SignedRoot, SignedValidatorRegistrationData,
+    SignedVoluntaryExit, Slot, SyncAggregatorSelectionData, SyncCommitteeContribution,
+    SyncCommitteeMessage, SyncSelectionProof, SyncSubnetId, ValidatorRegistrationData,
+    VoluntaryExit, graffiti::GraffitiString,
 };
 use validator_store::{
     AggregateToSign, AttestationToSign, ContributionToSign, DoppelgangerStatus,
@@ -1423,6 +1424,37 @@ impl<T: SlotClock + 'static, E: EthSpec> ValidatorStore for LighthouseValidatorS
             })
     }
 
+    async fn sign_payload_attestation(
+        &self,
+        validator_pubkey: PublicKeyBytes,
+        data: PayloadAttestationData,
+    ) -> Result<PayloadAttestationMessage, Error> {
+        let signing_context =
+            self.signing_context(Domain::PTCAttester, data.slot.epoch(E::slots_per_epoch()));
+
+        let validator_index = self
+            .validator_index(&validator_pubkey)
+            .ok_or(ValidatorStoreError::UnknownPubkey(validator_pubkey))?;
+
+        let signing_method = self.doppelganger_bypassed_signing_method(validator_pubkey)?;
+
+        let signature = signing_method
+            .get_signature::<E, FullPayload<E>>(
+                SignableMessage::PayloadAttestationData(&data),
+                signing_context,
+                &self.spec,
+                &self.task_executor,
+            )
+            .await
+            .map_err(Error::SpecificError)?;
+
+        Ok(PayloadAttestationMessage {
+            validator_index,
+            data,
+            signature,
+        })
+    }
+
     /// Sign an `ExecutionPayloadEnvelope` for Gloas (local building).
     /// The proposer acts as the builder and signs with the BeaconBuilder domain.
     async fn sign_execution_payload_envelope(