Add KZG proof and blob validation

beacon_node/beacon_chain/src/beacon_chain.rs

@@ -73,6 +73,7 @@ use fork_choice::{
 use futures::channel::mpsc::Sender;
 use itertools::process_results;
 use itertools::Itertools;
+use kzg::Kzg;
 use operation_pool::{AttestationRef, OperationPool, PersistedOperationPool, ReceivedPreCapella};
 use parking_lot::{Mutex, RwLock};
 use proto_array::{CountUnrealizedFull, DoNotReOrg, ProposerHeadError};
@@ -107,6 +108,7 @@ use store::{
 use task_executor::{ShutdownReason, TaskExecutor};
 use tree_hash::TreeHash;
 use types::beacon_state::CloneConfig;
+use types::blobs_sidecar::KzgCommitments;
 use types::consts::eip4844::MIN_EPOCHS_FOR_BLOBS_SIDECARS_REQUESTS;
 use types::consts::merge::INTERVALS_PER_SLOT;
 use types::*;
@@ -4760,39 +4762,60 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
                 .as_ref()
                 .ok_or(BlockProductionError::TrustedSetupNotInitialized)?;
             let beacon_block_root = block.canonical_root();
-            let expected_kzg_commitments = block.body().blob_kzg_commitments().map_err(|_| {
-                BlockProductionError::InvalidBlockVariant(
-                    "EIP4844 block does not contain kzg commitments".to_string(),
-                )
-            })?;
+            let expected_kzg_commitments: &KzgCommitments<T::EthSpec> =
+                block.body().blob_kzg_commitments().map_err(|_| {
+                    BlockProductionError::InvalidBlockVariant(
+                        "EIP4844 block does not contain kzg commitments".to_string(),
+                    )
+                })?;
+
+            if expected_kzg_commitments.len() != blobs.len() {
+                return Err(BlockProductionError::MissingKzgCommitment(format!(
+                    "Missing KZG commitment for slot {}. Expected {}, got: {}",
+                    slot,
+                    blobs.len(),
+                    expected_kzg_commitments.len()
+                )));
+            }
+
+            let kzg_proofs =
+                Self::compute_blob_kzg_proofs(kzg, &blobs, expected_kzg_commitments, slot)?;
+
+            kzg_utils::validate_blobs::<T::EthSpec>(
+                kzg,
+                expected_kzg_commitments,
+                &blobs,
+                &kzg_proofs,
+            )
+            .map_err(BlockProductionError::KzgError)?;
 
             let blob_sidecars = VariableList::from(
                 blobs
                     .into_iter()
                     .enumerate()
                     .map(|(blob_index, blob)| {
-                        BlobSidecar {
+                        let kzg_commitment = expected_kzg_commitments
+                            .get(blob_index)
+                            .expect("KZG commitment should exist for blob");
+
+                        let kzg_proof = kzg_proofs
+                            .get(blob_index)
+                            .expect("KZG proof should exist for blob");
+
+                        Ok(BlobSidecar {
                             block_root: beacon_block_root,
                             index: blob_index as u64,
                             slot,
                             block_parent_root: block.parent_root(),
                             proposer_index,
                             blob,
-                            kzg_commitment: expected_kzg_commitments[blob_index].clone(),
-                            kzg_proof: Default::default(), // TODO: compute KZG proof
-                        }
+                            kzg_commitment: *kzg_commitment,
+                            kzg_proof: *kzg_proof,
+                        })
                     })
-                    .collect::<Vec<BlobSidecar<T::EthSpec>>>(),
+                    .collect::<Result<Vec<BlobSidecar<T::EthSpec>>, BlockProductionError>>()?,
             );
 
-            // TODO: validate blobs
-            // kzg_utils::validate_blobs_sidecar(
-            //     kzg,
-            //     slot,
-            //     beacon_block_root,
-            //     expected_kzg_commitments,
-            //     &blobs_sidecar,
-            // ).map_err(BlockProductionError::KzgError)?;
             self.blob_cache.put(beacon_block_root, blob_sidecars);
         }
 
@@ -4809,6 +4832,29 @@ impl<T: BeaconChainTypes> BeaconChain<T> {
         Ok((block, state))
     }
 
+    fn compute_blob_kzg_proofs(
+        kzg: &Arc<Kzg>,
+        blobs: &Blobs<<T as BeaconChainTypes>::EthSpec>,
+        expected_kzg_commitments: &KzgCommitments<<T as BeaconChainTypes>::EthSpec>,
+        slot: Slot,
+    ) -> Result<Vec<KzgProof>, BlockProductionError> {
+        blobs
+            .iter()
+            .enumerate()
+            .map(|(blob_index, blob)| {
+                let kzg_commitment = expected_kzg_commitments.get(blob_index).ok_or(
+                    BlockProductionError::MissingKzgCommitment(format!(
+                        "Missing KZG commitment for slot {} blob index {}",
+                        slot, blob_index
+                    )),
+                )?;
+
+                kzg_utils::compute_blob_kzg_proof::<T::EthSpec>(kzg, blob, kzg_commitment.clone())
+                    .map_err(BlockProductionError::KzgError)
+            })
+            .collect::<Result<Vec<KzgProof>, BlockProductionError>>()
+    }
+
     /// This method must be called whenever an execution engine indicates that a payload is
     /// invalid.
     ///

beacon_node/beacon_chain/src/errors.rs

@@ -273,6 +273,7 @@ pub enum BlockProductionError {
     ShuttingDown,
     MissingSyncAggregate,
     MissingExecutionPayload,
+    MissingKzgCommitment(String),
     TokioJoin(tokio::task::JoinError),
     BeaconChain(BeaconChainError),
     InvalidPayloadFork,

beacon_node/beacon_chain/src/kzg_utils.rs

@@ -42,10 +42,11 @@ pub fn validate_blobs<T: EthSpec>(
 /// Compute the kzg proof given an ssz blob and its kzg commitment.
 pub fn compute_blob_kzg_proof<T: EthSpec>(
     kzg: &Kzg,
-    blob: Blob<T>,
+    blob: &Blob<T>,
     kzg_commitment: KzgCommitment,
 ) -> Result<KzgProof, KzgError> {
-    kzg.compute_blob_kzg_proof(ssz_blob_to_crypto_blob::<T>(blob), kzg_commitment)
+    // Avoid this blob clone
+    kzg.compute_blob_kzg_proof(ssz_blob_to_crypto_blob::<T>(blob.clone()), kzg_commitment)
 }
 
 /// Compute the kzg commitment for a given blob.