Implement challenge 34

src/rsa.rs

@@ -1,12 +1,26 @@
-pub fn expmod(base: u32, exp: u32, m: u32) -> u32 {
-    if exp == 0 {
-        return 1;
-    }
+use num_bigint::BigUint;
+use num_bigint::RandBigInt;
 
-    if exp % 2 == 0 {
-        let s = expmod(base, exp / 2, m);
-        (s * s) % m
-    } else {
-        (expmod(base, exp - 1, m) * base) % m
+#[derive(Clone)]
+pub struct PublicKey(pub BigUint);
+
+#[derive(Clone)]
+pub struct PrivateKey(pub BigUint);
+
+#[derive(Clone)]
+pub struct Keypair {
+    pub private: PrivateKey,
+    pub public: PublicKey,
+}
+
+impl Keypair {
+    pub fn make(p: &BigUint, g: &BigUint) -> Self {
+        let mut rng = rand::thread_rng();
+        let private = rng.gen_biguint_below(p);
+        let public = g.modpow(&private, p);
+        Self {
+            private: PrivateKey(private),
+            public: PublicKey(public),
+        }
     }
 }