diff --git a/libpaket/src/locker/crypto.rs b/libpaket/src/locker/crypto.rs
index abb0688..85f8e94 100644
--- a/libpaket/src/locker/crypto.rs
+++ b/libpaket/src/locker/crypto.rs
@@ -6,9 +6,10 @@ use ed25519_dalek::Signer;
 
 
 pub struct CustomerKeySeed {
-    postnumber: String,
-    seed: Seed,
-    uuid: Uuid,
+    pub postnumber: String,
+    pub seed: Seed,
+    pub uuid: Uuid,
+    pub device_id: Option<String>,
 }
 
 pub struct Seed {
@@ -44,17 +45,25 @@ impl CustomerKeySeed {
             postnumber,
             seed: Seed::random(),
             uuid: uuid::Uuid::new_v4(),
+            device_id: None,
         }
     }
 
-    pub fn from(postnumber: &String, seed: Vec<u8>, uuid: &Uuid) -> Self {
+    pub fn from(postnumber: &String, seed: Vec<u8>, uuid: &Uuid, device_id: String) -> Self {
         CustomerKeySeed {
             postnumber: postnumber.clone(),
             seed: Seed::from_bytes(seed),
-            uuid: uuid.clone()
+            uuid: uuid.clone(),
+            device_id: Some(device_id),
         }
     }
 
+    pub fn set_device_id(&mut self, device_id: String) {
+        assert!(self.device_id.is_none());
+
+        self.device_id = Some(device_id);
+    }
+
     pub(crate) fn sign(&self, message: &[u8]) -> String {
         let signing_key = SigningKey::from_bytes(self.seed.as_bytes());