From 8c780109966bd9364286c01e3785e485d70ea0c5 Mon Sep 17 00:00:00 2001
From: kevaundray <kevtheappdev@gmail.com>
Date: Thu, 1 Aug 2024 17:33:39 +1000
Subject: [PATCH] chore: Use reference to an array representing a blob instead
 of an owned KzgBlob (#6179)

* add KzgBlobRef type

* modify code to use KzgBlobRef

* clippy

* Remove Deneb blob related changes to maintain compatibility with `c-kzg-4844`.

---------

Co-authored-by: Jimmy Chen <jchen.tc@gmail.com>
---
 consensus/types/src/data_column_sidecar.rs    |  9 ++++++---
 crypto/kzg/src/lib.rs                         | 20 ++++++++++---------
 .../cases/kzg_compute_cells_and_kzg_proofs.rs |  6 +++---
 3 files changed, 20 insertions(+), 15 deletions(-)

diff --git a/consensus/types/src/data_column_sidecar.rs b/consensus/types/src/data_column_sidecar.rs
index 9b140ca0652..aa00e7d0213 100644
--- a/consensus/types/src/data_column_sidecar.rs
+++ b/consensus/types/src/data_column_sidecar.rs
@@ -9,7 +9,7 @@ use bls::Signature;
 use derivative::Derivative;
 #[cfg_attr(test, double)]
 use kzg::Kzg;
-use kzg::{Blob as KzgBlob, CellRef as KzgCellRef, Error as KzgError};
+use kzg::{CellRef as KzgCellRef, Error as KzgError};
 use kzg::{KzgCommitment, KzgProof};
 use merkle_proof::verify_merkle_proof;
 #[cfg(test)]
@@ -128,8 +128,11 @@ impl<E: EthSpec> DataColumnSidecar<E> {
         let blob_cells_and_proofs_vec = blobs
             .into_par_iter()
             .map(|blob| {
-                let blob = KzgBlob::from_bytes(blob).map_err(KzgError::from)?;
-                kzg.compute_cells_and_proofs(&blob)
+                let blob = blob
+                    .as_ref()
+                    .try_into()
+                    .expect("blob should have a guaranteed size due to FixedVector");
+                kzg.compute_cells_and_proofs(blob)
             })
             .collect::<Result<Vec<_>, KzgError>>()?;
 
diff --git a/crypto/kzg/src/lib.rs b/crypto/kzg/src/lib.rs
index b9f556d5a47..c45fb8dfdd0 100644
--- a/crypto/kzg/src/lib.rs
+++ b/crypto/kzg/src/lib.rs
@@ -20,8 +20,11 @@ pub use peerdas_kzg::{
     Cell, CellIndex as CellID, CellRef, TrustedSetup as PeerDASTrustedSetup,
 };
 use peerdas_kzg::{prover::ProverError, verifier::VerifierError, PeerDASContext};
+
 pub type CellsAndKzgProofs = ([Cell; CELLS_PER_EXT_BLOB], [KzgProof; CELLS_PER_EXT_BLOB]);
 
+pub type KzgBlobRef<'a> = &'a [u8; BYTES_PER_BLOB];
+
 #[derive(Debug)]
 pub enum Error {
     /// An error from the underlying kzg library.
@@ -173,15 +176,14 @@ impl Kzg {
     }
 
     /// Computes the cells and associated proofs for a given `blob` at index `index`.
-    pub fn compute_cells_and_proofs(&self, blob: &Blob) -> Result<CellsAndKzgProofs, Error> {
-        let blob_bytes: &[u8; BYTES_PER_BLOB] = blob
-            .as_ref()
-            .try_into()
-            .expect("Expected blob to have size {BYTES_PER_BLOB}");
-
+    #[allow(clippy::needless_lifetimes)]
+    pub fn compute_cells_and_proofs<'a>(
+        &self,
+        blob: KzgBlobRef<'a>,
+    ) -> Result<CellsAndKzgProofs, Error> {
         let (cells, proofs) = self
             .context
-            .compute_cells_and_kzg_proofs(blob_bytes)
+            .compute_cells_and_kzg_proofs(blob)
             .map_err(Error::ProverKZG)?;
 
         // Convert the proof type to a c-kzg proof type
@@ -245,11 +247,11 @@ impl Kzg {
 }
 
 pub mod mock {
-    use crate::{Blob, Cell, CellsAndKzgProofs, BYTES_PER_CELL, CELLS_PER_EXT_BLOB};
+    use crate::{Cell, CellsAndKzgProofs, KzgBlobRef, BYTES_PER_CELL, CELLS_PER_EXT_BLOB};
     use crate::{Error, KzgProof};
 
     #[allow(clippy::type_complexity)]
-    pub fn compute_cells_and_proofs(_blob: &Blob) -> Result<CellsAndKzgProofs, Error> {
+    pub fn compute_cells_and_proofs(_blob: KzgBlobRef) -> Result<CellsAndKzgProofs, Error> {
         let empty_cells = vec![Cell::new([0; BYTES_PER_CELL]); CELLS_PER_EXT_BLOB]
             .try_into()
             .expect("expected {CELLS_PER_EXT_BLOB} number of items");
diff --git a/testing/ef_tests/src/cases/kzg_compute_cells_and_kzg_proofs.rs b/testing/ef_tests/src/cases/kzg_compute_cells_and_kzg_proofs.rs
index de3eca46cb6..74a44fdddfc 100644
--- a/testing/ef_tests/src/cases/kzg_compute_cells_and_kzg_proofs.rs
+++ b/testing/ef_tests/src/cases/kzg_compute_cells_and_kzg_proofs.rs
@@ -1,6 +1,6 @@
 use super::*;
 use crate::case_result::compare_result;
-use kzg::{Blob as KzgBlob, CellsAndKzgProofs};
+use kzg::CellsAndKzgProofs;
 use serde::Deserialize;
 use std::marker::PhantomData;
 
@@ -32,11 +32,11 @@ impl<E: EthSpec> Case for KZGComputeCellsAndKZGProofs<E> {
 
     fn result(&self, _case_index: usize, _fork_name: ForkName) -> Result<(), Error> {
         let cells_and_proofs = parse_blob::<E>(&self.input.blob).and_then(|blob| {
-            let blob = KzgBlob::from_bytes(&blob).map_err(|e| {
+            let blob = blob.as_ref().try_into().map_err(|e| {
                 Error::InternalError(format!("Failed to convert blob to kzg blob: {e:?}"))
             })?;
             let kzg = get_kzg()?;
-            kzg.compute_cells_and_proofs(&blob).map_err(|e| {
+            kzg.compute_cells_and_proofs(blob).map_err(|e| {
                 Error::InternalError(format!("Failed to compute cells and kzg proofs: {e:?}"))
             })
         });