From 31b5c3e30ef9e260fc5395c377027d3183e7ea54 Mon Sep 17 00:00:00 2001
From: Agnish Ghosh <80243668+agnxsh@users.noreply.github.com>
Date: Tue, 24 Sep 2024 18:16:05 +0530
Subject: [PATCH] add: inclusion proof and dc sidecar verification (#6577)

* add: inclusion proof and dc sidecar verification

* review 1
---
 beacon_chain/spec/eip7594_helpers.nim | 55 ++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/beacon_chain/spec/eip7594_helpers.nim b/beacon_chain/spec/eip7594_helpers.nim
index e1824d610..71cf41d6e 100644
--- a/beacon_chain/spec/eip7594_helpers.nim
+++ b/beacon_chain/spec/eip7594_helpers.nim
@@ -306,4 +306,57 @@ func get_extended_sample_count*(samples_per_slot: int,
         worstCaseConditionCount, i) <= falsePositiveThreshold:
       return i
 
-  NUMBER_OF_COLUMNS
\ No newline at end of file
+  NUMBER_OF_COLUMNS
+
+# https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.6/specs/_features/eip7594/p2p-interface.md#verify_data_column_sidecar_inclusion_proof
+proc verify_data_column_sidecar_inclusion_proof*(sidecar: DataColumnSidecar):
+                                                 Result[void, cstring] =
+  ## Verify if the given KZG Commitments are in included
+  ## in the beacon block or not
+  let gindex = 
+    KZG_COMMITMENTS_INCLUSION_PROOF_DEPTH_GINDEX.GeneralizedIndex
+  if not is_valid_merkle_branch(
+      hash_tree_root(sidecar.kzg_commitments),
+      sidecar.kzg_commitments_inclusion_proof,
+      KZG_COMMITMENTS_INCLUSION_PROOF_DEPTH.int,
+      get_subtree_index(gindex),
+      sidecar.signed_block_header.message.body_root):
+    
+    return err("DataColumnSidecar: Inclusion proof is invalid")
+
+  ok()
+
+# https://github.com/ethereum/consensus-specs/blob/v1.5.0-alpha.6/specs/_features/eip7594/p2p-interface.md#verify_data_column_sidecar_kzg_proofs
+proc verify_data_column_sidecar_kzg_proofs*(sidecar: DataColumnSidecar):
+                                            Result[void, cstring] =
+  ## Verify if the KZG Proofs consisting in the `DataColumnSidecar`
+  ## is valid or not.
+  
+  # Check if the data column sidecar index < NUMBER_OF_COLUMNS
+  if not (sidecar.index < NUMBER_OF_COLUMNS):
+    return err("Data column sidecar index exceeds the NUMBER_OF_COLUMNS")
+
+  # Check is the sidecar column length = sidecar.kzg_commitments length
+  # and sidecar.kzg_commitments length = sidecar.kzg_proofs length
+  if not (sidecar.column.len == sidecar.kzg_commitments.len):
+    return err("Data column sidecar length is not equal to the kzg_commitments length")
+
+  if not (sidecar.kzg_commitments.len == sidecar.kzg_proofs.len):
+    return err("Sidecar kzg_commitments length is not equal to the kzg_proofs length")
+
+  # Iterate through the cell indices
+  var cellIndices = 
+    newSeq[CellIndex](MAX_BLOB_COMMITMENTS_PER_BLOCK)
+  for _ in 0..<sidecar.column.len:
+    cellIndices.add(sidecar.index * sidecar.column.lenu64)
+
+  let res = 
+    verifyCellKzgProofBatch(sidecar.kzg_commitments.asSeq,
+                            cellIndices,
+                            sidecar.column.asSeq,
+                            sidecar.kzg_proofs.asSeq)
+
+  if res.isErr():
+    return err("DataColumnSidecar: validation failed")
+
+  ok()
\ No newline at end of file