iPhone 5S fingerprint scanner: How it works

Apple has announced that its new iPhone 5S will come with a fingerprint scanner called Touch ID, making it quicker and more importantly safer to unlock your iPhone and make purchases.
So how does it work
The technology comes built into the home button, with Touch ID using a laser cut sapphire crystal, together with the touch sensor, to take a high-res image of your fingerprint and analyse it to determine if you are indeed the phones owner.
It is designed to provide accurate readings from any angle, so the motion to unlock your device ought to be as automatic as it is now. Moreover, the more you use Touch ID the better it gets at recognising your fingerprint.
Wont this complicated bit of technology drain the phones juice
Not so says Apple, as the scanner is only activated when needed, preserving battery life.
Is it completely secure
All fingerprint information is encrypted and stored securely inside the devices A7 chip and never on Apple servers or backed up to iCloud making it NSA tapping-proof among other things.
Touch ID can also be used as a safer way to approve purchases from the iTunes Store, App Store or iBooks Store.