Shift over fe_cmov/fe_isnonzero/fe_isnegative.

src/ed25519/fe.rs

@@ -821,13 +821,15 @@ fn negate() {
     });
 }
 
-pub fn fe_cmov(f: &mut FieldElement, g: &FieldElement, bl: bool)
+impl FieldElement {
+    pub fn cmov(&mut self, g: &FieldElement, bl: bool)
     {
         let b = if bl { -1 } else { 0 };
         for i in 0..10 {
-        let mut x = f.value[i] ^ g.value[i];
+            let mut x = self.value[i] ^ g.value[i];
             x &= b;
-        f.value[i] ^= x;
+            self.value[i] ^= x;
+        }
     }
 }
 
@@ -845,14 +847,15 @@ fn cmov() {
         let b = bbytes.len() > 1;
         let c = test_from_bytes(&cbytes);
         let mut r = FieldElement::new();
-        fe_cmov(&mut r, &a, b);
+        r.cmov(&a, b);
         assert_eq!(r, c);
     });
 }
 
-pub fn fe_isnonzero(f: &FieldElement) -> bool
+impl FieldElement {
+    pub fn isnonzero(&self) -> bool
     {
-    let s = f.to_bytes();
+        let s = self.to_bytes();
         let mut res = false;
         for i in 0..32 {
             res |= s[i] != 0;
@@ -860,11 +863,12 @@ pub fn fe_isnonzero(f: &FieldElement) -> bool
         res
     }
 
-pub fn fe_isnegative(f: &FieldElement) -> bool
+    pub fn isnegative(&self) -> bool
     {
-    let s = f.to_bytes();
+        let s = self.to_bytes();
         s[0] & 1 == 1
     }
+}
 
 #[cfg(test)]
 #[test]
@@ -880,8 +884,8 @@ fn is_tests() {
         println!("a: {:?}", a);
         let z = zbytes.len() > 1;
         let n = nbytes.len() > 1;
-        assert_eq!(z, fe_isnonzero(&a));
-        assert_eq!(n, fe_isnegative(&a));
+        assert_eq!(z, a.isnonzero());
+        assert_eq!(n, a.isnegative());
     });
 }
 

src/ed25519/point.rs

@@ -58,15 +58,15 @@ impl Point {
       let mut vxx = hx.square();
       vxx *= &v;
       let mut check = &vxx - &u; /* vx^2-u */
-      if fe_isnonzero(&check) {
+      if check.isnonzero() {
         check = &vxx + &u;
-        if fe_isnonzero(&check) {
+        if check.isnonzero() {
           return None;
         }
         hx *= &SQRTM1;
       }
 
-      if fe_isnegative(&hx) != ((s[31] >> 7) == 1) {
+      if hx.isnegative() != ((s[31] >> 7) == 1) {
         hx = -&hx;
       }
 
@@ -473,9 +473,9 @@ fn equal(b: i8, c: i8) -> bool
 
 fn cmov(t: &mut Precomp, u: &Precomp, b: bool)
 {
-  fe_cmov(&mut t.yplusx, &u.yplusx, b);
-  fe_cmov(&mut t.yminusx, &u.yminusx, b);
-  fe_cmov(&mut t.xy2d, &u.xy2d, b);
+  t.yplusx.cmov(&u.yplusx, b);
+  t.yminusx.cmov(&u.yminusx, b);
+  t.xy2d.cmov(&u.xy2d, b);
 }
 
 fn negative(b: i8) -> u8
@@ -1796,7 +1796,7 @@ fn into_encoded_point(x: &FieldElement, y: &FieldElement, z: &FieldElement) -> V
     let x_over_z = x * &recip;
     let y_over_z = y * &recip;
     let mut bytes = y_over_z.to_bytes();
-    let sign_bit = if fe_isnegative(&x_over_z) { 1 } else { 0 };
+    let sign_bit = if x_over_z.isnegative() { 1 } else { 0 };
     // The preceding computations must execute in constant time, but this
     // doesn't need to.
     bytes[31] ^= sign_bit << 7;