diff --git a/src/apis/v1/context/auth_key/handlers.rs b/src/apis/v1/context/auth_key/handlers.rs
index d21f0829..cb1cd111 100644
--- a/src/apis/v1/context/auth_key/handlers.rs
+++ b/src/apis/v1/context/auth_key/handlers.rs
@@ -31,7 +31,7 @@ pub async fn delete_auth_key_handler(
 ) -> Response {
     match Key::from_str(&seconds_valid_or_key.0) {
         Err(_) => invalid_auth_key_param_response(&seconds_valid_or_key.0),
-        Ok(key) => match tracker.remove_auth_key(&key.to_string()).await {
+        Ok(key) => match tracker.remove_auth_key(&key).await {
             Ok(_) => ok_response(),
             Err(e) => failed_to_delete_key_response(e),
         },
diff --git a/src/databases/mod.rs b/src/databases/mod.rs
index 247f571d..0af6f572 100644
--- a/src/databases/mod.rs
+++ b/src/databases/mod.rs
@@ -9,7 +9,7 @@ use async_trait::async_trait;
 
 use self::error::Error;
 use crate::protocol::info_hash::InfoHash;
-use crate::tracker::auth;
+use crate::tracker::auth::{self, Key};
 
 pub(self) struct Builder<T>
 where
@@ -63,25 +63,19 @@ pub trait Database: Sync + Send {
 
     async fn save_persistent_torrent(&self, info_hash: &InfoHash, completed: u32) -> Result<(), Error>;
 
-    // todo: replace type `&str` with `&InfoHash`
-    async fn get_info_hash_from_whitelist(&self, info_hash: &str) -> Result<Option<InfoHash>, Error>;
+    async fn get_info_hash_from_whitelist(&self, info_hash: &InfoHash) -> Result<Option<InfoHash>, Error>;
 
     async fn add_info_hash_to_whitelist(&self, info_hash: InfoHash) -> Result<usize, Error>;
 
     async fn remove_info_hash_from_whitelist(&self, info_hash: InfoHash) -> Result<usize, Error>;
 
-    // todo: replace type `&str` with `&Key`
-    async fn get_key_from_keys(&self, key: &str) -> Result<Option<auth::ExpiringKey>, Error>;
+    async fn get_key_from_keys(&self, key: &Key) -> Result<Option<auth::ExpiringKey>, Error>;
 
     async fn add_key_to_keys(&self, auth_key: &auth::ExpiringKey) -> Result<usize, Error>;
 
-    // todo: replace type `&str` with `&Key`
-    async fn remove_key_from_keys(&self, key: &str) -> Result<usize, Error>;
+    async fn remove_key_from_keys(&self, key: &Key) -> Result<usize, Error>;
 
     async fn is_info_hash_whitelisted(&self, info_hash: &InfoHash) -> Result<bool, Error> {
-        Ok(self
-            .get_info_hash_from_whitelist(&info_hash.clone().to_string())
-            .await?
-            .is_some())
+        Ok(self.get_info_hash_from_whitelist(info_hash).await?.is_some())
     }
 }
diff --git a/src/databases/mysql.rs b/src/databases/mysql.rs
index f0c7ec1d..f6918974 100644
--- a/src/databases/mysql.rs
+++ b/src/databases/mysql.rs
@@ -147,12 +147,12 @@ impl Database for Mysql {
         Ok(conn.exec_drop(COMMAND, params! { info_hash_str, completed })?)
     }
 
-    async fn get_info_hash_from_whitelist(&self, info_hash: &str) -> Result<Option<InfoHash>, Error> {
+    async fn get_info_hash_from_whitelist(&self, info_hash: &InfoHash) -> Result<Option<InfoHash>, Error> {
         let mut conn = self.pool.get().map_err(|e| (e, DRIVER))?;
 
         let select = conn.exec_first::<String, _, _>(
             "SELECT info_hash FROM whitelist WHERE info_hash = :info_hash",
-            params! { info_hash },
+            params! { "info_hash" => info_hash.to_hex_string() },
         )?;
 
         let info_hash = select.map(|f| InfoHash::from_str(&f).expect("Failed to decode InfoHash String from DB!"));
@@ -183,11 +183,13 @@ impl Database for Mysql {
         Ok(1)
     }
 
-    async fn get_key_from_keys(&self, key: &str) -> Result<Option<auth::ExpiringKey>, Error> {
+    async fn get_key_from_keys(&self, key: &Key) -> Result<Option<auth::ExpiringKey>, Error> {
         let mut conn = self.pool.get().map_err(|e| (e, DRIVER))?;
 
-        let query =
-            conn.exec_first::<(String, i64), _, _>("SELECT `key`, valid_until FROM `keys` WHERE `key` = :key", params! { key });
+        let query = conn.exec_first::<(String, i64), _, _>(
+            "SELECT `key`, valid_until FROM `keys` WHERE `key` = :key",
+            params! { "key" => key.to_string() },
+        );
 
         let key = query?;
 
@@ -211,10 +213,10 @@ impl Database for Mysql {
         Ok(1)
     }
 
-    async fn remove_key_from_keys(&self, key: &str) -> Result<usize, Error> {
+    async fn remove_key_from_keys(&self, key: &Key) -> Result<usize, Error> {
         let mut conn = self.pool.get().map_err(|e| (e, DRIVER))?;
 
-        conn.exec_drop("DELETE FROM `keys` WHERE key = :key", params! { key })?;
+        conn.exec_drop("DELETE FROM `keys` WHERE key = :key", params! { "key" => key.to_string() })?;
 
         Ok(1)
     }
diff --git a/src/databases/sqlite.rs b/src/databases/sqlite.rs
index 4bf2931d..adb201de 100644
--- a/src/databases/sqlite.rs
+++ b/src/databases/sqlite.rs
@@ -156,12 +156,12 @@ impl Database for Sqlite {
         }
     }
 
-    async fn get_info_hash_from_whitelist(&self, info_hash: &str) -> Result<Option<InfoHash>, Error> {
+    async fn get_info_hash_from_whitelist(&self, info_hash: &InfoHash) -> Result<Option<InfoHash>, Error> {
         let conn = self.pool.get().map_err(|e| (e, DRIVER))?;
 
         let mut stmt = conn.prepare("SELECT info_hash FROM whitelist WHERE info_hash = ?")?;
 
-        let mut rows = stmt.query([info_hash])?;
+        let mut rows = stmt.query([info_hash.to_hex_string()])?;
 
         let query = rows.next()?;
 
@@ -200,7 +200,7 @@ impl Database for Sqlite {
         }
     }
 
-    async fn get_key_from_keys(&self, key: &str) -> Result<Option<auth::ExpiringKey>, Error> {
+    async fn get_key_from_keys(&self, key: &Key) -> Result<Option<auth::ExpiringKey>, Error> {
         let conn = self.pool.get().map_err(|e| (e, DRIVER))?;
 
         let mut stmt = conn.prepare("SELECT key, valid_until FROM keys WHERE key = ?")?;
@@ -211,9 +211,9 @@ impl Database for Sqlite {
 
         Ok(key.map(|f| {
             let expiry: i64 = f.get(1).unwrap();
-            let id: String = f.get(0).unwrap();
+            let key: String = f.get(0).unwrap();
             auth::ExpiringKey {
-                key: id.parse::<Key>().unwrap(),
+                key: key.parse::<Key>().unwrap(),
                 valid_until: DurationSinceUnixEpoch::from_secs(expiry.unsigned_abs()),
             }
         }))
@@ -237,10 +237,10 @@ impl Database for Sqlite {
         }
     }
 
-    async fn remove_key_from_keys(&self, key: &str) -> Result<usize, Error> {
+    async fn remove_key_from_keys(&self, key: &Key) -> Result<usize, Error> {
         let conn = self.pool.get().map_err(|e| (e, DRIVER))?;
 
-        let deleted = conn.execute("DELETE FROM keys WHERE key = ?", [key])?;
+        let deleted = conn.execute("DELETE FROM keys WHERE key = ?", [key.to_string()])?;
 
         if deleted == 1 {
             // should only remove a single record.
diff --git a/src/protocol/info_hash.rs b/src/protocol/info_hash.rs
index 32063672..fd7602cd 100644
--- a/src/protocol/info_hash.rs
+++ b/src/protocol/info_hash.rs
@@ -24,6 +24,11 @@ impl InfoHash {
     pub fn bytes(&self) -> [u8; 20] {
         self.0
     }
+
+    #[must_use]
+    pub fn to_hex_string(&self) -> String {
+        self.to_string()
+    }
 }
 
 impl std::fmt::Display for InfoHash {
@@ -197,6 +202,13 @@ mod tests {
         assert_eq!(output, "ffffffffffffffffffffffffffffffffffffffff");
     }
 
+    #[test]
+    fn an_info_hash_should_return_its_a_40_utf8_lowercased_char_hex_representations_as_string() {
+        let info_hash = InfoHash::from_str("FFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF").unwrap();
+
+        assert_eq!(info_hash.to_hex_string(), "ffffffffffffffffffffffffffffffffffffffff");
+    }
+
     #[test]
     fn an_info_hash_can_be_created_from_a_valid_20_byte_array_slice() {
         let info_hash: InfoHash = [255u8; 20].as_slice().into();
diff --git a/src/tracker/mod.rs b/src/tracker/mod.rs
index 326afbf0..8a973979 100644
--- a/src/tracker/mod.rs
+++ b/src/tracker/mod.rs
@@ -202,10 +202,9 @@ impl Tracker {
     /// # Panics
     ///
     /// Will panic if key cannot be converted into a valid `Key`.
-    pub async fn remove_auth_key(&self, key: &str) -> Result<(), databases::error::Error> {
-        // todo: change argument `key: &str` to `key: &Key`
+    pub async fn remove_auth_key(&self, key: &Key) -> Result<(), databases::error::Error> {
         self.database.remove_key_from_keys(key).await?;
-        self.keys.write().await.remove(&key.parse::<Key>().unwrap());
+        self.keys.write().await.remove(key);
         Ok(())
     }
 
@@ -1175,12 +1174,12 @@ mod tests {
                 async fn it_should_remove_an_authentication_key() {
                     let tracker = private_tracker();
 
-                    let key = tracker.generate_auth_key(Duration::from_secs(100)).await.unwrap();
+                    let expiring_key = tracker.generate_auth_key(Duration::from_secs(100)).await.unwrap();
 
-                    let result = tracker.remove_auth_key(&key.id().to_string()).await;
+                    let result = tracker.remove_auth_key(&expiring_key.id()).await;
 
                     assert!(result.is_ok());
-                    assert!(tracker.verify_auth_key(&key.id()).await.is_err());
+                    assert!(tracker.verify_auth_key(&expiring_key.id()).await.is_err());
                 }
 
                 #[tokio::test]