For many users, mobile devices have become an indispensable tool in their increasingly digitized everyday lives. Many tasks of daily life are performed on the move: the terminal device becomes the key to the car and apartment, stores boarding passes and is used to access the bank account. Most such services require the secure storage of identity data and cryptographic key material. Secure transmission, storage and access control to their data is therefore a top priority for the user. While the mobile device enables a wide variety of different applications through apps, the security-relevant data required for these applications is often still transmitted via insecure and proprietary channels (e.g. e-mail, SMS) and there are doubts about data security. For security reasons, external media ...