From a4a48c74e92f37a6768189ea5decfc42a536a205 Mon Sep 17 00:00:00 2001
From: Alon Haramati <91828241+alonh5@users.noreply.github.com>
Date: Wed, 20 Mar 2024 10:23:33 +0200
Subject: [PATCH] Add OODS verification error. (#502)
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This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/starkware-libs/stwo/502)
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---
 src/core/prover/mod.rs | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/core/prover/mod.rs b/src/core/prover/mod.rs
index 914a693b3..633abc55d 100644
--- a/src/core/prover/mod.rs
+++ b/src/core/prover/mod.rs
@@ -181,10 +181,11 @@ pub fn verify(
         &proof.trace_oods_values,
         random_coeff,
     );
-    assert_eq!(
-        composition_polynomial_oods_value,
-        combine_secure_value(proof.composition_polynomial_column_oods_values)
-    );
+    if composition_polynomial_oods_value
+        != combine_secure_value(proof.composition_polynomial_column_oods_values)
+    {
+        return Err(VerificationError::OodsNotMatching);
+    }
     channel.mix_felts(&proof.trace_oods_values.flatten());
     channel.mix_felts(&proof.composition_polynomial_column_oods_values);
 
@@ -303,6 +304,11 @@ pub enum ProvingError {
 
 #[derive(Clone, Copy, Debug, Error)]
 pub enum VerificationError {
+    #[error(
+        "The composition polynomial OODS value does not match the trace OODS values
+    (DEEP-ALI failure)."
+    )]
+    OodsNotMatching,
     #[error(transparent)]
     Fri(#[from] FriVerificationError),
 }