feat: Blob Tx Sidecar Iterator

crates/eips/src/eip4844/mod.rs

@@ -85,6 +85,20 @@ pub const BYTES_PER_PROOF: usize = 48;
 /// A Blob serialized as 0x-prefixed hex string
 pub type Blob = FixedBytes<BYTES_PER_BLOB>;
 
+/// Helper function to deserialize boxed blobs.
+#[cfg(feature = "serde")]
+pub fn deserialize_blob<'de, D>(deserializer: D) -> Result<alloc::boxed::Box<Blob>, D::Error>
+where
+    D: serde::de::Deserializer<'de>,
+{
+    use serde::Deserialize;
+    let raw_blob = <alloy_primitives::Bytes>::deserialize(deserializer)?;
+    let blob = alloc::boxed::Box::new(
+        Blob::try_from(raw_blob.as_ref()).map_err(serde::de::Error::custom)?,
+    );
+    Ok(blob)
+}
+
 /// A commitment/proof serialized as 0x-prefixed hex string
 pub type Bytes48 = FixedBytes<48>;
 

crates/eips/src/eip4844/sidecar.rs

@@ -3,6 +3,7 @@
 use crate::eip4844::{
     kzg_to_versioned_hash, Blob, Bytes48, BYTES_PER_BLOB, BYTES_PER_COMMITMENT, BYTES_PER_PROOF,
 };
+use alloc::boxed::Box;
 use alloy_primitives::{bytes::BufMut, B256};
 use alloy_rlp::{Decodable, Encodable};
 
@@ -12,6 +13,10 @@ use crate::eip4844::MAX_BLOBS_PER_BLOCK;
 #[cfg(not(feature = "std"))]
 use alloc::vec::Vec;
 
+/// The versioned hash version for KZG.
+#[cfg(feature = "kzg")]
+pub(crate) const VERSIONED_HASH_VERSION_KZG: u8 = 0x01;
+
 /// This represents a set of blobs, and its corresponding commitments and proofs.
 ///
 /// This type encodes and decodes the fields without an rlp header.
@@ -32,6 +37,96 @@ pub struct BlobTransactionSidecar {
     pub proofs: Vec<Bytes48>,
 }
 
+impl IntoIterator for BlobTransactionSidecar {
+    type Item = BlobTransactionSidecarItem;
+    type IntoIter = alloc::vec::IntoIter<BlobTransactionSidecarItem>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.blobs
+            .into_iter()
+            .zip(self.commitments)
+            .zip(self.proofs)
+            .enumerate()
+            .map(|(index, ((blob, commitment), proof))| BlobTransactionSidecarItem {
+                index,
+                blob: Box::new(blob),
+                kzg_commitment: commitment,
+                kzg_proof: proof,
+            })
+            .collect::<Vec<_>>()
+            .into_iter()
+    }
+}
+
+/// A single blob sidecar.
+#[derive(Clone, Debug, Default, PartialEq, Eq, Hash)]
+#[repr(C)]
+#[cfg_attr(feature = "serde", derive(serde::Serialize, serde::Deserialize))]
+pub struct BlobTransactionSidecarItem {
+    /// The index of this item within the [BlobTransactionSidecar].
+    pub index: usize,
+    /// The blob in this sidecar item.
+    #[cfg_attr(feature = "serde", serde(deserialize_with = "super::deserialize_blob"))]
+    pub blob: Box<Blob>,
+    /// The KZG commitment.
+    pub kzg_commitment: Bytes48,
+    /// The KZG proof.
+    pub kzg_proof: Bytes48,
+}
+
+#[cfg(feature = "kzg")]
+impl BlobTransactionSidecarItem {
+    /// `VERSIONED_HASH_VERSION_KZG ++ sha256(commitment)[1..]`
+    pub fn to_kzg_versioned_hash(&self) -> [u8; 32] {
+        use sha2::Digest;
+        let commitment = self.kzg_commitment.as_slice();
+        let mut hash: [u8; 32] = sha2::Sha256::digest(commitment).into();
+        hash[0] = VERSIONED_HASH_VERSION_KZG;
+        hash
+    }
+
+    /// Verifies the KZG proof of a blob to ensure its integrity and correctness.
+    pub fn verify_blob_kzg_proof(&self) -> Result<(), BlobTransactionValidationError> {
+        let binding = crate::eip4844::env_settings::EnvKzgSettings::Default;
+        let settings = binding.get();
+
+        let blob = c_kzg::Blob::from_bytes(self.blob.as_slice())
+            .map_err(BlobTransactionValidationError::KZGError)?;
+
+        let commitment = c_kzg::Bytes48::from_bytes(self.kzg_commitment.as_slice())
+            .map_err(BlobTransactionValidationError::KZGError)?;
+
+        let proof = c_kzg::Bytes48::from_bytes(self.kzg_proof.as_slice())
+            .map_err(BlobTransactionValidationError::KZGError)?;
+
+        let result = c_kzg::KzgProof::verify_blob_kzg_proof(&blob, &commitment, &proof, settings)
+            .map_err(BlobTransactionValidationError::KZGError)?;
+
+        result.then_some(()).ok_or(BlobTransactionValidationError::InvalidProof)
+    }
+
+    /// Verify the blob sidecar against its [crate::NumHash].
+    pub fn verify_blob(&self, hash: &crate::NumHash) -> Result<(), BlobTransactionValidationError> {
+        if self.index != hash.number as usize {
+            let blob_hash_part = B256::from_slice(&self.blob[0..32]);
+            return Err(BlobTransactionValidationError::WrongVersionedHash {
+                have: blob_hash_part,
+                expected: hash.hash,
+            });
+        }
+
+        let computed_hash = self.to_kzg_versioned_hash();
+        if computed_hash != hash.hash {
+            return Err(BlobTransactionValidationError::WrongVersionedHash {
+                have: computed_hash.into(),
+                expected: hash.hash,
+            });
+        }
+
+        self.verify_blob_kzg_proof()
+    }
+}
+
 #[cfg(any(test, feature = "arbitrary"))]
 impl<'a> arbitrary::Arbitrary<'a> for BlobTransactionSidecar {
     fn arbitrary(u: &mut arbitrary::Unstructured<'a>) -> arbitrary::Result<Self> {
@@ -139,11 +234,7 @@ impl BlobTransactionSidecar {
         }
         .map_err(BlobTransactionValidationError::KZGError)?;
 
-        if res {
-            Ok(())
-        } else {
-            Err(BlobTransactionValidationError::InvalidProof)
-        }
+        res.then_some(()).ok_or(BlobTransactionValidationError::InvalidProof)
     }
 
     /// Returns an iterator over the versioned hashes of the commitments.

crates/rpc-types-beacon/src/sidecar.rs

@@ -1,6 +1,6 @@
 use crate::header::Header;
-use alloy_eips::eip4844::{Blob, BlobTransactionSidecar, Bytes48};
-use alloy_primitives::{Bytes, B256};
+use alloy_eips::eip4844::{deserialize_blob, Blob, BlobTransactionSidecar, Bytes48};
+use alloy_primitives::B256;
 use serde::{Deserialize, Serialize};
 use serde_with::{serde_as, DisplayFromStr};
 use std::vec::IntoIter;
@@ -101,18 +101,6 @@ pub struct BlobData {
     pub kzg_commitment_inclusion_proof: Vec<B256>,
 }
 
-/// Helper function to deserialize boxed blobs
-fn deserialize_blob<'de, D>(deserializer: D) -> Result<Box<Blob>, D::Error>
-where
-    D: serde::de::Deserializer<'de>,
-{
-    let raw_blob = <Bytes>::deserialize(deserializer)?;
-
-    let blob = Box::new(Blob::try_from(raw_blob.as_ref()).map_err(serde::de::Error::custom)?);
-
-    Ok(blob)
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;