diff --git a/src/handlers/mod.rs b/src/handlers/mod.rs
index edffba2..952e08f 100644
--- a/src/handlers/mod.rs
+++ b/src/handlers/mod.rs
@@ -4,6 +4,13 @@ use webauthn_rs::prelude::*;
 use crate::models::AppState;
 
 pub async fn start_webauthn_registration(app_state: AppState) -> Result<impl warp::Reply, Infallible> {
-    app_state.webauthn.start_passkey_registration();
+    let mut db = app_state.db.lock().await;
+    // TODO: query the user
+    let mut user = db.users.first_mut().unwrap();
+
+    let (creation_challenge_response, passkey_registration) = app_state.webauthn.start_passkey_registration(user.uuid, &user.user_name, &user.display_name, None).unwrap();
+
+    user.creation_challenge_response = Some(creation_challenge_response);
+
     Ok(warp::reply::json(&"hello".to_string()))
 }
diff --git a/src/models/mod.rs b/src/models/mod.rs
index 23de6d6..a32d0a5 100644
--- a/src/models/mod.rs
+++ b/src/models/mod.rs
@@ -1,15 +1,22 @@
 use url::Url;
-use std::sync::{Arc, Mutex};
+use std::sync::{Arc};
+
+use tokio::sync::{Mutex};
 
 use webauthn_rs::prelude::Uuid;
 use webauthn_rs::{Webauthn, WebauthnBuilder};
 
-pub type Db = Arc<Mutex<Vec<User>>>;
+pub type Db = Arc<Mutex<Database>>;
+
+pub struct Database {
+    pub users: Vec<User>
+}
 
 pub struct User {
     pub uuid: Uuid,
     pub user_name: String,
-    pub display_name: String
+    pub display_name: String,
+    pub creation_challenge_response: Option<webauthn_rs::prelude::CreationChallengeResponse>,
 }
 
 pub struct AppState {
@@ -24,7 +31,19 @@ impl AppState {
         let builder = WebauthnBuilder::new(rp, &rp_origin).expect("Invalid configuration");
         let builder = builder.rp_name("LocalHost");
         let webauthn = Arc::new(builder.build().expect("Invalid configuration"));
-        let db: Db = Arc::new(Mutex::new(Vec::new()));
-        AppState {webauthn, db}
+        let user: User = User { 
+            uuid: Uuid::new_v4(),
+            user_name: "felix".to_string(),
+            display_name: "Félix".to_string(),
+            creation_challenge_response: None,
+        };
+        let db: Db = Arc::new(Mutex::new(Database {
+            users: Vec::from([user])
+        }));
+        
+        AppState {
+            webauthn,
+            db,
+        }
     }
 }