diff --git a/src/database.rs b/src/database.rs
index cb61a89..ba0faaa 100644
--- a/src/database.rs
+++ b/src/database.rs
@@ -4,6 +4,6 @@ use crate::*;
 pub trait Database {
     fn new(dbpath: &str) -> Self;
     fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>>;
-    fn put(&mut self, key: &[u8]) -> Result<()>;
+    fn put(&mut self, key: &[u8], value: &[u8]) -> Result<()>;
     fn delete(&mut self, key: &[u8]) -> Result<()>;
 }
diff --git a/src/hasher.rs b/src/hasher.rs
index f2cb554..2bae535 100644
--- a/src/hasher.rs
+++ b/src/hasher.rs
@@ -1,7 +1,12 @@
+pub trait ToBytes {
+    fn to_bytes(&self) -> Vec<u8>;
+}
+
 /// Trait that must be implemented for Hash Function
 pub trait Hasher {
-    type Fr: Copy + Eq + Default;
+    type Fr: Copy + Eq + Default + From<Vec<u8>> + Into<Vec<u8>>;
 
     fn new() -> Self;
+    fn default_leaf() -> Self::Fr;
     fn hash(input: &[Self::Fr]) -> Self::Fr;
 }
diff --git a/src/tree.rs b/src/tree.rs
index a503a4b..5980396 100644
--- a/src/tree.rs
+++ b/src/tree.rs
@@ -11,19 +11,39 @@ where
     next_index: usize,
 }
 
+pub(crate) struct Key(usize, usize);
+
+impl From<Key> for Vec<u8> {
+    fn from(key: Key) -> Vec<u8> {
+        todo!()
+    }
+}
+
 impl<D, H> MerkleTree<D, H>
 where
     D: Database,
     H: Hasher,
 {
     /// Creates new `MerkleTree`
-    pub fn new(depth: usize, dbpath: &str) -> Self {
-        Self {
-            db: Database::new(dbpath),
+    pub fn new(depth: usize, dbpath: &str) -> Result<Self> {
+        // TODO: Use open instead of new, and check if the database is exists
+        let mut db: D = Database::new(dbpath);
+
+        db.put(&Vec::<u8>::from(Key(depth, 0)), &H::default_leaf().into())?;
+        for i in (0..depth).rev() {
+            let prev = db.get(&Vec::<u8>::from(Key(i + 1, 0)))?.unwrap();
+            db.put(
+                &Vec::<u8>::from(Key(i, 0)),
+                &H::hash(&[prev.clone().into(), prev.into()]).into(),
+            )?;
+        }
+
+        Ok(Self {
+            db,
             h: Hasher::new(),
             depth,
             next_index: 0,
-        }
+        })
     }
 
     /// Inserts a leaf to the next available index
@@ -31,6 +51,11 @@ where
         todo!()
     }
 
+    /// Recalculates `Merkle Tree` from the specified key
+    fn recalculate_from(&mut self, key: usize) {
+        todo!()
+    }
+
     /// Deletes a  leaf at the `key` by setting it to its default value
     pub fn delete(&mut self, key: usize) {
         todo!()