fix: catch panics from EC point creation (e.g. the point is at infinity)

.gitignore

@@ -4,6 +4,7 @@ examples/**/target/
 examples/9
 node_modules
 pkg/
+.idea
 
 # Yarn
 .pnp.*

acvm-repo/bn254_blackbox_solver/src/fixed_base_scalar_mul.rs

@@ -47,17 +47,29 @@ pub fn fixed_base_scalar_mul(
     }
 }
 
+fn create_point(x: FieldElement, y: FieldElement) -> Result<grumpkin::SWAffine, String> {
+    let point = grumpkin::SWAffine::new_unchecked(x.into_repr(), y.into_repr());
+    if !point.is_on_curve() {
+        return Err(format!("Point ({}, {}) is not on curve", x.to_hex(), y.to_hex()));
+    };
+    if !point.is_in_correct_subgroup_assuming_on_curve() {
+        return Err(format!("Point ({}, {}) is not in correct subgroup", x.to_hex(), y.to_hex()));
+    };
+    Ok(point)
+}
+
 pub fn embedded_curve_add(
     input1_x: FieldElement,
     input1_y: FieldElement,
     input2_x: FieldElement,
     input2_y: FieldElement,
 ) -> Result<(FieldElement, FieldElement), BlackBoxResolutionError> {
-    let mut point1 = grumpkin::SWAffine::new(input1_x.into_repr(), input1_y.into_repr());
-    let point2 = grumpkin::SWAffine::new(input2_x.into_repr(), input2_y.into_repr());
-    let res = point1 + point2;
-    point1 = res.into();
-    if let Some((res_x, res_y)) = point1.xy() {
+    let point1 = create_point(input1_x, input1_y)
+        .map_err(|e| BlackBoxResolutionError::Failed(BlackBoxFunc::EmbeddedCurveAdd, e))?;
+    let point2 = create_point(input2_x, input2_y)
+        .map_err(|e| BlackBoxResolutionError::Failed(BlackBoxFunc::EmbeddedCurveAdd, e))?;
+    let res = grumpkin::SWAffine::from(point1 + point2);
+    if let Some((res_x, res_y)) = res.xy() {
         Ok((FieldElement::from_repr(*res_x), FieldElement::from_repr(*res_y)))
     } else {
         Err(BlackBoxResolutionError::Failed(
@@ -72,6 +84,7 @@ mod grumpkin_fixed_base_scalar_mul {
     use ark_ff::BigInteger;
 
     use super::*;
+
     #[test]
     fn smoke_test() -> Result<(), BlackBoxResolutionError> {
         let input = FieldElement::one();
@@ -84,6 +97,7 @@ mod grumpkin_fixed_base_scalar_mul {
         assert_eq!(y, res.1.to_hex());
         Ok(())
     }
+
     #[test]
     fn low_high_smoke_test() -> Result<(), BlackBoxResolutionError> {
         let low = FieldElement::one();
@@ -103,9 +117,9 @@ mod grumpkin_fixed_base_scalar_mul {
         let max_limb = FieldElement::from(u128::MAX);
         let invalid_limb = max_limb + FieldElement::one();
 
-        let expected_error =  Err(BlackBoxResolutionError::Failed(
+        let expected_error = Err(BlackBoxResolutionError::Failed(
             BlackBoxFunc::FixedBaseScalarMul,
-            "Limb 0000000000000000000000000000000100000000000000000000000000000000 is not less than 2^128".into()
+            "Limb 0000000000000000000000000000000100000000000000000000000000000000 is not less than 2^128".into(),
         ));
 
         let res = fixed_base_scalar_mul(&invalid_limb, &FieldElement::zero());
@@ -128,7 +142,23 @@ mod grumpkin_fixed_base_scalar_mul {
             res,
             Err(BlackBoxResolutionError::Failed(
                 BlackBoxFunc::FixedBaseScalarMul,
-                "30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47 is not a valid grumpkin scalar".into()
+                "30644e72e131a029b85045b68181585d97816a916871ca8d3c208c16d87cfd47 is not a valid grumpkin scalar".into(),
+            ))
+        );
+    }
+
+    #[test]
+    fn rejects_addition_of_points_not_in_curve() {
+        let x = FieldElement::from(1u128);
+        let y = FieldElement::from(2u128);
+
+        let res = embedded_curve_add(x, y, x, y);
+
+        assert_eq!(
+            res,
+            Err(BlackBoxResolutionError::Failed(
+                BlackBoxFunc::EmbeddedCurveAdd,
+                "Point (0000000000000000000000000000000000000000000000000000000000000001, 0000000000000000000000000000000000000000000000000000000000000002) is not on curve".into(),
             ))
         );
     }