For my purposes, it will have to be sufficient that I can register the app with a server and store the token in IndexDB. It will be unfortunate if there is a time limit on this.
If there is a time limit, then I can store the user's pin on the server, for speed of reauthentication. I cant have an alpha-numeric password as it will be used in a flying aircraft, so big buttons are required.
Most of the employees in my client's company uses iOS (Phones and tablets).