add hmac

ring/src/main.rs

@@ -1,3 +1,15 @@
-fn main() {
-    println!("Hello, world!");
+use ring::{hmac, rand, error::Unspecified};
+
+fn main() -> Result<(), Unspecified> {
+    let rng = rand::SystemRandom::new();
+    let key = hmac::Key::generate(hmac::HMAC_SHA256, &rng)?;
+
+    let msg = "hello, world";
+    let tag = hmac::sign(&key, msg.as_bytes());
+
+    println!("{:?}", tag);
+    hmac::verify(&key, msg.as_bytes(), tag.as_ref())?;
+    println!("Verify success");
+
+    Ok(())
 }