diff --git a/src/crypto.rs b/src/crypto.rs
index 9527e39..70f87f1 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -15,6 +15,16 @@ pub struct PublicKey {
     pub key: [u8; 32]
 }
 
+impl PublicKey {
+    pub fn verify_sign(&self, raw: &Vec<u8>, sign: &Vec<u8>) -> bool {
+        PK::from_bytes(&self.key).unwrap()
+            .verify(
+                raw,
+                &Signature::from_bytes(sign.clone().into_boxed_slice().as_ref()).unwrap(),
+            ).is_ok()
+    }
+}
+
 
 pub struct Keys {
     pub pair: Keypair,
@@ -31,11 +41,7 @@ pub fn verify_sign(msg: &crate::message::Message) -> bool {
     match &msg.clone().sign {
         Sign::NoSign => true,
         Sign::Signed(key, sign) => {
-            PK::from_bytes(&key.key).unwrap()
-                .verify(
-                    msg.get_hash().as_ref(),
-                    &Signature::from_bytes(sign.clone().into_boxed_slice().as_ref()).unwrap(),
-                ).is_ok()
+            key.verify_sign(&msg.get_hash(), sign)
         }
     }
 }
diff --git a/src/lib.rs b/src/lib.rs
index a3b5fa6..bea47d6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -24,6 +24,30 @@ mod tests {
         }
     }
 
+    mod crypto {
+        use crate::crypto::{PublicKey, Keys, verify_sign};
+
+        #[test]
+        fn creation() {
+            let key_pair = Keys::gen();
+        }
+
+        #[test]
+        fn signing() {
+            let key_pair = Keys::gen();
+            key_pair.sign(&[1u8; 129].to_vec());
+        }
+
+        #[test]
+        fn verification() {
+            let key_pair = Keys::gen();
+            let sign = key_pair.sign(&[1u8; 129].to_vec());
+            assert!(key_pair.get_public().verify_sign(&[1u8; 129].to_vec(), &sign));
+            assert!(!key_pair.get_public().verify_sign(&[0u8; 129].to_vec(), &sign));
+            assert!(!key_pair.get_public().verify_sign(&[1u8; 129].to_vec(), &[0u8; 64].to_vec()));
+        }
+    }
+
     mod message {
         use crate::message::{MsgType, Message};
         use crate::crypto::Keys;