Notifications: Fix notification extension using outdated key (#119)

Sources/PushNotifications/PushNotificationCipher.swift

@@ -13,9 +13,7 @@ import Common
 class PushNotificationCipher {
 
     static func decrypt(payload: String, iv: String) -> PushNotification? {
-        // Decode PrivateKey from base64 to String
-        guard let privateKey = UserSessionFactory.shared.getCurrentNotificationDeviceConfiguration()?.notificationsEncryptionKey,
-              let privateKeyAsData = Data(base64Encoded: privateKey) else {
+        guard let privateKey = UserSessionFactory.shared.getCurrentNotificationEncryptionKey() else {
             return nil
         }
 
@@ -24,7 +22,7 @@ class PushNotificationCipher {
             return nil
         }
 
-        let uint8Key = [UInt8](privateKeyAsData)
+        let uint8Key = [UInt8](privateKey)
         let uint8Iv = [UInt8](ivAsData)
 
         guard let payloadAsData = Data(base64Encoded: payload) else {

Sources/UserStore/UserSession.swift

@@ -120,6 +120,21 @@ public class UserSession: ObservableObject {
         notificationDeviceConfigurations.first(where: { $0.institutionIdentifier == institution && $0.username == username })
     }
 
+    /// Gets the currently active key for decrypting notifications.
+    /// This force-loads the latest keychain data because the notification extension can outlive the app,
+    /// thus the key may have changed while the UserSession is still in memory
+    public func getCurrentNotificationEncryptionKey() -> Data? {
+        setupLoginData()
+        setupInstitutionSelection()
+        setupNotificationData()
+        guard let config = getCurrentNotificationDeviceConfiguration(),
+              let key = config.notificationsEncryptionKey,
+              let keyAsData = Data(base64Encoded: key) else {
+            return nil
+        }
+        return keyAsData
+    }
+
     public func saveInstitution(identifier: InstitutionIdentifier?) {
         self.institution = identifier