Make EdwardsPoint (x, y) not public.

src/circuit/ecc.rs

@@ -32,8 +32,8 @@ use super::boolean::Boolean;
 
 #[derive(Clone)]
 pub struct EdwardsPoint<E: Engine> {
-    pub x: AllocatedNum<E>,
-    pub y: AllocatedNum<E>
+    x: AllocatedNum<E>,
+    y: AllocatedNum<E>
 }
 
 /// Perform a fixed-base scalar multiplication with
@@ -84,6 +84,14 @@ pub fn fixed_base_multiplication<E, CS>(
 }
 
 impl<E: JubjubEngine> EdwardsPoint<E> {
+    pub fn get_x(&self) -> &AllocatedNum<E> {
+        &self.x
+    }
+
+    pub fn get_y(&self) -> &AllocatedNum<E> {
+        &self.y
+    }
+
     pub fn assert_not_small_order<CS>(
         &self,
         mut cs: CS,
@@ -183,12 +191,6 @@ impl<E: JubjubEngine> EdwardsPoint<E> {
         )
     }
 
-    /// This extracts the x-coordinate, which is an injective
-    /// encoding for elements of the prime order subgroup.
-    pub fn into_num(&self) -> AllocatedNum<E> {
-        self.x.clone()
-    }
-
     /// Returns `self` if condition is true, and the neutral
     /// element (0, 1) otherwise.
     pub fn conditionally_select<CS>(

src/circuit/mod.rs

@@ -229,7 +229,7 @@ impl<'a, E: JubjubEngine> Circuit<E> for Spend<'a, E> {
         let mut position_bits = vec![];
 
         // Injective encoding.
-        let mut cur = cm.x.clone();
+        let mut cur = cm.get_x().clone();
 
         for (i, e) in self.auth_path.into_iter().enumerate() {
             let cs = &mut cs.namespace(|| format!("merkle tree hash {}", i));
@@ -268,7 +268,7 @@ impl<'a, E: JubjubEngine> Circuit<E> for Spend<'a, E> {
                 pedersen_hash::Personalization::MerkleTree(i),
                 &preimage,
                 self.params
-            )?.x; // Injective encoding
+            )?.get_x().clone(); // Injective encoding
         }
 
         assert_eq!(position_bits.len(), tree_depth);
@@ -473,7 +473,7 @@ impl<'a, E: JubjubEngine> Circuit<E> for Output<'a, E> {
         // since we know it is prime order, and we know that
         // the x-coordinate is an injective encoding for
         // prime-order elements.
-        cm.x.inputize(cs.namespace(|| "commitment"))?;
+        cm.get_x().inputize(cs.namespace(|| "commitment"))?;
 
         Ok(())
     }

src/circuit/pedersen_hash.rs

@@ -176,8 +176,8 @@ mod test {
                     params
                 ).into_xy();
 
-                assert_eq!(res.x.get_value().unwrap(), expected.0);
-                assert_eq!(res.y.get_value().unwrap(), expected.1);
+                assert_eq!(res.get_x().get_value().unwrap(), expected.0);
+                assert_eq!(res.get_y().get_value().unwrap(), expected.1);
 
                 // Test against the output of a different personalization
                 let unexpected = ::pedersen_hash::pedersen_hash::<Bls12, _>(
@@ -186,8 +186,8 @@ mod test {
                     params
                 ).into_xy();
 
-                assert!(res.x.get_value().unwrap() != unexpected.0);
-                assert!(res.y.get_value().unwrap() != unexpected.1);
+                assert!(res.get_x().get_value().unwrap() != unexpected.0);
+                assert!(res.get_y().get_value().unwrap() != unexpected.1);
             }
         }
     }