add div and pow

src/finite_field.rs

@@ -1,4 +1,4 @@
-use std::ops::{Add, Sub, Mul, AddAssign, SubAssign};
+use std::{ops::{Add, Sub, Mul, AddAssign, SubAssign, Div, Rem}, fmt::Debug};
 
 pub trait DefaultNumber {
     fn zero() -> Self;
@@ -23,6 +23,23 @@ where
     }
 }
 
+impl<T> FiniteFieldElement<T>
+where
+    T: Rem<Output = T> + Add<Output = T> + Sub<Output = T> + PartialEq + PartialOrd + Copy + DefaultNumber + Debug
+{
+    fn pow(self, e: T) -> Self {
+        let one = T::one();
+        let mut r = Self::new(one, self.p);
+        let mut i = e % (self.p - one);
+        let zero = T::zero();
+        while i > zero {
+            r = r * self;
+            i = i - one;
+        }
+        r
+    }
+}
+
 impl<T> Add for FiniteFieldElement<T>
 where
     T: Add<Output = T> + Sub<Output = T> + PartialEq + PartialOrd + Copy
@@ -31,7 +48,7 @@ where
 
     fn add(self, rhs: Self) -> Self::Output {
         if self.p != rhs.p {
-            panic!("Different field.")
+            panic!("Cannot add different field value.")
         }
         let sum = self.value + rhs.value;
         if sum >= self.p {
@@ -59,7 +76,7 @@ where
 
     fn sub(self, rhs: Self) -> Self::Output {
         if self.p != rhs.p {
-            panic!("Different field.");
+            panic!("Cannot sub different field value.");
         }
         if self.value < rhs.value {
             Self::new(self.p - rhs.value + self.value , self.p)
@@ -86,7 +103,7 @@ where
 
     fn mul(self, rhs: Self) -> Self::Output {
         if self.p != rhs.p {
-            panic!("Different field.");
+            panic!("Cannot mul different field value.");
         }
         let one = T::one();
         let zero = T::zero();
@@ -99,3 +116,15 @@ where
         r
     }
 }
+
+impl<T> Div for FiniteFieldElement<T>
+where
+    T: Add<Output = T> + Sub<Output = T> + Rem<Output = T> + PartialEq + PartialOrd + Copy + DefaultNumber + Debug
+{
+    type Output = Self;
+
+    fn div(self, rhs: Self) -> Self::Output {
+        let one = T::one();
+        self * rhs.pow(self.p - one - one)
+    }
+}

src/lib.rs

@@ -0,0 +1 @@
+pub mod finite_field;

src/main.rs

@@ -1,24 +0,0 @@
-use finite_field::DefaultNumber;
-use primitive_types::U512;
-
-use crate::finite_field::FiniteFieldElement;
-
-mod finite_field;
-
-impl DefaultNumber for U512 {
-    fn zero() -> Self {
-        U512::from(0)
-    }
-
-    fn one() -> Self {
-        U512::from(1)
-    }
-}
-
-fn main() {
-    let value = FiniteFieldElement::new(U512::from(2u8), U512::MAX);
-    let value2 = FiniteFieldElement::new(U512::from(3u8), U512::MAX);
-    println!("{:?}", value + value2);
-    println!("{:?}", value - value2);
-    println!("{:?}", value * value2);
-}