problem 33

1 files changed, 28 insertions, 0 deletions

diff --git a/src/dh.rs b/src/dh.rs
new file mode 100644
index 0000000..24c2277
--- /dev/null
+++ b/src/dh.rs
@@ -0,0 +1,28 @@
+use num_bigint::RandBigInt;
+
+pub struct DHKeyPair {
+    pub p: num_bigint::BigUint,
+    pub g: num_bigint::BigUint,
+    pub pubkey: num_bigint::BigUint,
+    privkey: num_bigint::BigUint,
+}
+
+impl DHKeyPair {
+    pub fn new(p: num_bigint::BigUint, g: num_bigint::BigUint) -> DHKeyPair {
+        let privkey = rand::thread_rng().gen_biguint_below(&p);
+        let pubkey = g.modpow(&privkey, &p);
+        DHKeyPair {
+            p,
+            g,
+            pubkey,
+            privkey,
+        }
+    }
+
+    pub fn key_exchange(
+        &self,
+        other_pubkey: &num_bigint::BigUint,
+    ) -> num_bigint::BigUint {
+        other_pubkey.modpow(&self.privkey, &self.p)
+    }
+}