Add more gossip verification conditions

consensus/types/src/signed_blobs_sidecar.rs

@@ -1,7 +1,9 @@
-use crate::{BlobsSidecar, EthSpec};
+use crate::{
+    signing_data::SignedRoot, BlobsSidecar, ChainSpec, Domain, EthSpec, Fork, Hash256, PublicKey,
+    SigningData,
+};
 use bls::Signature;
 use serde_derive::{Deserialize, Serialize};
-use ssz::Encode;
 use ssz_derive::{Decode, Encode};
 use tree_hash::TreeHash;
 use tree_hash_derive::TreeHash;
@@ -21,4 +23,36 @@ impl<T: EthSpec> SignedBlobsSidecar<T> {
             signature,
         }
     }
+
+    /// Verify `self.signature`.
+    ///
+    /// If the root of `blob_sidecar.message` is already known it can be passed in via `object_root_opt`.
+    /// Otherwise, it will be computed locally.
+    pub fn verify_signature(
+        &self,
+        object_root_opt: Option<Hash256>,
+        pubkey: &PublicKey,
+        fork: &Fork,
+        genesis_validators_root: Hash256,
+        spec: &ChainSpec,
+    ) -> bool {
+        let domain = spec.get_domain(
+            self.message.beacon_block_slot.epoch(T::slots_per_epoch()),
+            Domain::BlobsSideCar,
+            fork,
+            genesis_validators_root,
+        );
+
+        let message = if let Some(object_root) = object_root_opt {
+            SigningData {
+                object_root,
+                domain,
+            }
+            .tree_hash_root()
+        } else {
+            self.message.signing_root(domain)
+        };
+
+        self.signature.verify(pubkey, message)
+    }
 }