About Touch ID Fingerprint Sensor Security on the iPhone 5s

Apple has posted a help document outlining the security safeguards it takes for the new Touch ID fingerprint sensor on the iPhone 5s.

Security safeguards
Every fingerprint is unique, so it is rare that even a small section of two separate fingerprints are alike enough to register as a match for Touch ID. The probability of this happening is 1 in 50,000 for one enrolled finger. This is much better than the 1 in 10,000 odds of guessing a typical 4-digit passcode. Although some passcodes, like "1234", may be more easily guessed, there is no such thing as an easily guessable fingerprint pattern. Instead, the 1 in 50,000 probability means it requires trying up to 50,000 different fingerprints until potentially finding a random match. But Touch ID only allows five unsuccessful fingerprint match attempts before you must enter your passcode, and you cannot proceed until doing so.
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