iPhone 's fingerprint sensor on the Apple iPhones does n't always work the way it should . After you register your fingerprint — a process known as enrolling — an encrypted mathematical representation of that information is stored on the device 's A7 processor in what 's called the `` secure enclave . '' Some 5S do n't approve fingerprints they 're supposed to approve . Sensor is susceptible to problems caused by dust , moisture , and electrostatic discharge , . User error could also be causing some people 's issues with the Touch ID system .
iPhone 's fingerprint sensor on the Apple iPhones does n't always work the way it should . Some 5S do n't approve fingerprints they 're supposed to approve . Sensor is susceptible to problems caused by dust , moisture , and electrostatic discharge , . User error could also be causing some people 's issues with the Touch ID system .