diff --git a/src/crypto.rs b/src/crypto.rs
index 602704f..cff1a90 100644
--- a/src/crypto.rs
+++ b/src/crypto.rs
@@ -1,63 +1,81 @@
-extern crate rand;
-
-use crate::ed25519_dalek::ed25519::signature::Signature;
-use crate::ed25519_dalek::Signer;
-use crate::ed25519_dalek::Verifier;
 use alloc::vec::Vec;
-use ed25519_dalek::{Keypair, PublicKey as PK};
-use rand::rngs::OsRng;
 use serde::{Deserialize, Serialize};
 
+/// Public key of a node
 #[derive(Debug, PartialEq, Serialize, Deserialize, Clone)]
 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()
+    /// Check if the sign is valid for gived data and key
+    pub fn verify_sign(&self, _data: &[u8], _sign: &[u8]) -> bool {
+        todo!()
     }
-}
 
-pub struct Keys {
-    pub pair: Keypair,
-}
-
-impl Keys {
-    pub fn gen() -> Keys {
-        Keys {
-            pair: Keypair::generate(&mut OsRng {}),
-        }
+    /// Encrypt some data for a user with this public key
+    pub fn encrypt_data(&self, _data: &[u8]) -> Vec<u8> {
+        todo!()
     }
 }
 
-#[derive(Debug, PartialEq, Serialize, Deserialize, Clone)]
-pub enum Sign {
-    NoSign,
-    Signed(PublicKey /* source */, Vec<u8> /* sign */),
-}
+/// Key pair (public and secret) for a node, should be stored locally
+#[derive(Debug, Serialize, Deserialize, Clone)]
+pub struct Keys {}
 
-pub fn verify_sign(data: &Vec<u8>, sign: &Sign) -> bool {
-    match sign {
-        Sign::NoSign => true,
-        Sign::Signed(key, sign) => key.verify_sign(data, sign),
+impl Keys {
+    /// Generate new random key
+    pub fn generate() -> Keys {
+        todo!()
     }
 }
 
 impl Keys {
-    pub fn sign(&self, content: &Vec<u8>) -> Vec<u8> {
-        self.pair.sign(content.as_ref()).to_bytes().to_vec()
+    /// Sign content using these keys
+    pub fn sign(&self, _content: &[u8]) -> Vec<u8> {
+        todo!()
+    }
+
+    /// Decrypt data
+    pub fn decrypt_data(&self, _data_encrypted: &[u8]) -> Option<Vec<u8>> {
+        todo!()
     }
 
+    /// Get public key
     pub fn get_public(&self) -> PublicKey {
-        PublicKey {
-            key: *self.clone().pair.public.as_bytes(),
-        }
+        todo!()
     }
 }
+
+#[test]
+fn test_encrypt() {
+    let data = vec![0, 5, 8, 135, 67];
+    let keys = Keys::generate();
+    assert_eq!(
+        keys.decrypt_data(keys.get_public().encrypt_data(data)),
+        Some(data)
+    );
+}
+
+#[test]
+fn test_invalid_encrypt() {
+    let data = vec![0, 5, 8, 135, 67];
+    let keys_1 = Keys::generate();
+    let keys_2 = Keys::generate();
+    assert!(keys_2.decrypt_data(keys_1.get_public().encrypt_data(data)) != Some(data));
+}
+
+#[test]
+fn test_signing() {
+    let data = vec![0, 5, 8, 135, 67];
+    let keys = Keys::generate();
+    assert!(keys.get_public().verify_sign(data, keys.sign(data)));
+}
+
+#[test]
+fn test_invalid_signing() {
+    let data = vec![0, 5, 8, 135, 67];
+    let keys_1 = Keys::generate();
+    let keys_2 = Keys::generate();
+    assert!(keys_2.get_public().verify_sign(data, keys_1.sign(data)));
+}
diff --git a/src/lib.rs b/src/lib.rs
index f41498a..e332a88 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -4,6 +4,8 @@
 extern crate alloc;
 extern crate rand;
 
+mod crypto;
+
 #[cfg(test)]
 mod tests {
     #[test]