From e25fed64cbf48c9949d5bb051fad41ff37e358c8 Mon Sep 17 00:00:00 2001
From: guipublic <guipublic@gmail.com>
Date: Mon, 15 Apr 2024 11:48:10 +0000
Subject: [PATCH] fix field inversion

---
 acvm-repo/acvm/src/pwg/blackbox/bigint.rs          | 2 +-
 test_programs/execution_success/bigint/src/main.nr | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/acvm-repo/acvm/src/pwg/blackbox/bigint.rs b/acvm-repo/acvm/src/pwg/blackbox/bigint.rs
index f094bb1ba20..a47afa5049a 100644
--- a/acvm-repo/acvm/src/pwg/blackbox/bigint.rs
+++ b/acvm-repo/acvm/src/pwg/blackbox/bigint.rs
@@ -105,7 +105,7 @@ impl BigIntSolver {
             }
             BlackBoxFunc::BigIntMul => lhs * rhs,
             BlackBoxFunc::BigIntDiv => {
-                lhs * rhs.modpow(&(&modulus - BigUint::from(1_u32)), &modulus)
+                lhs * rhs.modpow(&(&modulus - BigUint::from(2_u32)), &modulus)
             } //TODO ensure that modulus is prime
             _ => unreachable!("ICE - bigint_op must be called for an operation"),
         };
diff --git a/test_programs/execution_success/bigint/src/main.nr b/test_programs/execution_success/bigint/src/main.nr
index db269d63ac0..908cab8accc 100644
--- a/test_programs/execution_success/bigint/src/main.nr
+++ b/test_programs/execution_success/bigint/src/main.nr
@@ -10,11 +10,11 @@ fn main(mut x: [u8; 5], y: [u8; 5]) {
         assert(a_bytes[i] == x[i]);
         assert(b_bytes[i] == y[i]);
     }
+    //Regression for issue #4578
+    let d = a * b;
+    assert(d / b == a);
 
-    let d = a * b - b;
-    let d1 = bigint::Secpk1Fq::from_le_bytes(597243850900842442924.to_le_bytes(10));
-    assert(d1 == d);
-    // big_int_example(x[0], x[1]);
+    big_int_example(x[0], x[1]);
 }
 
 // docs:start:big_int_example