I realized that if I was ever robbed of my phone and killed, the perp could use my fingers to unlock the phone and get all my data.
If being robbed, killed, and having your dead fingers used to unlock the contents of your iPhone is a very likely possibility for you, then owning an iPhone is the
least of your worries right now.
Address the issues that make your life that dangerous, OR the issues that make you
think it's that dangerous. Then, worry about whether you want an iPhone.
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Here is my solution:
1. Set the phone to delete all data after 10 attempts.
2. Don't use the thumb, you have 10 fingers (hence the genius of Apple setting the number of attempts to 10!!)
Actually, with TouchID, you have five attempts before TouchID shuts down and you're required to use a passcode to unlock.
3. For the finger you do use, set it at a different angle, so even if they guess the right finger, they have to also guess the correct angle.
Voila! A more secure phone.
As many have demonstrated (and as your point out) TouchID has its flaws and is imperfect. But, TouchID was not meant to be perfect.
For the most part, TouchID was meant to make a phone more secure for the less-worried crowd, who feel that even a 4-digit PIN is too much hassle to deal with when trying to use their phones. The rationale being that something, anything, is better than nothing. For these people, it's thought that if you present them with something really simple (a single touch of the finger on the home button) to authenticate instead of a passcode, they'll be motivated more to lock their phones and make them a little bit more secure.
Even for payments: Having a device that requires a fingerprint to authorize payments is a lot more secure than pulling out a piece of plastic, with the payment details clearly printed on the face, for all to see.
If, on the other hand, you're super paranoid, or super-targeted by people who want your state secrets, then Touch ID is not for you. To be honest, most smartphones wouldn't be for you. The
Boeing Black smartphone might be more your speed.