Ultimately its a device you're carrying around with you, if someone wants access they're probably going to get it, all you're aiming to stop is chance opportuni

Ultimately its a device you're carrying around with you, if someone wants access they're probably going to get it, all you're aiming to stop is chance opportunists. Pin, fingerprint reader (that works) is enough. Btw, I don't think 'casual attackers' really fits with access to, and willingness to go through cctv.