diff --git a/src/Socialbox/Managers/ContactManager.php b/src/Socialbox/Managers/ContactManager.php
index 2401f1c..a1f35dc 100644
--- a/src/Socialbox/Managers/ContactManager.php
+++ b/src/Socialbox/Managers/ContactManager.php
@@ -8,7 +8,6 @@
     use PDO;
     use PDOException;
     use Socialbox\Classes\Configuration;
-    use Socialbox\Classes\Cryptography;
     use Socialbox\Classes\Database;
     use Socialbox\Classes\Validator;
     use Socialbox\Enums\Types\ContactRelationshipType;
diff --git a/src/Socialbox/Objects/Standard/Contact.php b/src/Socialbox/Objects/Standard/Contact.php
index 4d56f5a..d259177 100644
--- a/src/Socialbox/Objects/Standard/Contact.php
+++ b/src/Socialbox/Objects/Standard/Contact.php
@@ -89,6 +89,18 @@
             return $this->knownKeys;
         }
 
+        public function signatureExists(string $signatureUuid): bool
+        {
+            foreach($this->knownKeys as $key)
+            {
+                if($key->getUuid() === $signatureUuid)
+                {
+                    return true;
+                }
+            }
+            return false;
+        }
+
         /**
          * Retrieves the timestamp when the contact was added.
          *