primefield: field_element_type! now impls Invert (#1163)

The trait is sourced from `crypto-bigint`

Author: tarcieri

bign256/src/arithmetic/field.rs

@@ -34,7 +34,6 @@ use crate::{BignP256, FieldBytes, U256};
 use elliptic_curve::{
     FieldBytesEncoding,
     ff::PrimeField,
-    ops::Invert,
     subtle::{Choice, ConstantTimeEq, CtOption},
 };
 
@@ -122,14 +121,6 @@ impl PrimeField for FieldElement {
     const DELTA: Self = Self::from_u64(4);
 }
 
-impl Invert for FieldElement {
-    type Output = CtOption<Self>;
-
-    fn invert(&self) -> CtOption<Self> {
-        self.invert()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::FieldElement;

bign256/src/arithmetic/scalar.rs

@@ -21,7 +21,7 @@ use elliptic_curve::{
     Curve as _, Error, FieldBytesEncoding, Result, ScalarPrimitive,
     bigint::Limb,
     ff::PrimeField,
-    ops::{Invert, Reduce},
+    ops::Reduce,
     scalar::{FromUintUnchecked, IsHigh},
     subtle::{Choice, ConditionallySelectable, ConstantTimeEq, ConstantTimeGreater, CtOption},
 };
@@ -119,14 +119,6 @@ impl FromUintUnchecked for Scalar {
     }
 }
 
-impl Invert for Scalar {
-    type Output = CtOption<Self>;
-
-    fn invert(&self) -> CtOption<Self> {
-        self.invert()
-    }
-}
-
 impl IsHigh for Scalar {
     fn is_high(&self) -> Choice {
         const MODULUS_SHR1: U256 = BignP256::ORDER.shr_vartime(1);

p384/src/arithmetic/field.rs

@@ -29,7 +29,6 @@ use elliptic_curve::{
     FieldBytesEncoding,
     bigint::U384,
     ff::PrimeField,
-    ops::Invert,
     subtle::{Choice, ConstantTimeEq, CtOption},
 };
 
@@ -137,14 +136,6 @@ impl PrimeField for FieldElement {
     }
 }
 
-impl Invert for FieldElement {
-    type Output = CtOption<Self>;
-
-    fn invert(&self) -> CtOption<Self> {
-        self.invert()
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::FieldElement;

p384/src/arithmetic/scalar.rs

@@ -28,7 +28,7 @@ use elliptic_curve::{
     Curve as _, Error, FieldBytesEncoding, Result, ScalarPrimitive,
     bigint::{ArrayEncoding, Limb},
     ff::PrimeField,
-    ops::{Invert, Reduce, ReduceNonZero},
+    ops::{Reduce, ReduceNonZero},
     scalar::{FromUintUnchecked, IsHigh},
     subtle::{Choice, ConditionallySelectable, ConstantTimeEq, ConstantTimeGreater, CtOption},
 };
@@ -172,14 +172,6 @@ impl FromUintUnchecked for Scalar {
     }
 }
 
-impl Invert for Scalar {
-    type Output = CtOption<Self>;
-
-    fn invert(&self) -> CtOption<Self> {
-        self.invert()
-    }
-}
-
 impl IsHigh for Scalar {
     fn is_high(&self) -> Choice {
         const MODULUS_SHR1: U384 = NistP384::ORDER.shr_vartime(1);

primefield/src/lib.rs

@@ -43,7 +43,6 @@ mod fiat;
 /// - `pub fn sqrt`
 ///
 /// # Trait impls
-/// - `AsRef<$arr>`
 /// - `ConditionallySelectable`
 /// - `ConstantTimeEq`
 /// - `ConstantTimeGreater`
@@ -64,6 +63,7 @@ mod fiat;
 /// - `Neg`
 /// - `Shr`
 /// - `ShrAssign`
+/// - `Invert`
 #[macro_export]
 macro_rules! field_element_type {
     (
@@ -393,6 +393,14 @@ macro_rules! field_element_type {
             }
         }
 
+        impl $crate::bigint::Invert for $fe {
+            type Output = CtOption<Self>;
+
+            fn invert(&self) -> CtOption<Self> {
+                self.invert()
+            }
+        }
+
         impl $crate::subtle::ConditionallySelectable for $fe {
             fn conditional_select(a: &Self, b: &Self, choice: Choice) -> Self {
                 Self(<$uint>::conditional_select(&a.0, &b.0, choice))