Fingerprint recognition has become a popular feature of many smartphones, providing a convenient and trusted method for unlocking the device and for authenticating payments and passwords. In general, a fingerprint sensor delivers a faster and more secure alternative to other device-unlock security measures such as PINs, passwords, or patterns entered on a virtual keypad, which can easily be observed and copied.
No matter which authentication scheme is used, it’s likely that at some point users will experience unlock problems. The tiny, virtual keyboard found on smartphones leads to typing errors for PINs and passwords, and biometric authentication methods have their own unique unlock issues as well.
Biometric unlock failures are considered “nuisance rejects” and are statistically characterized as the false rejection ratio (FRR) for the authentication scheme. For mobile devices, consumers will tolerate a noticeable FRR and re-authenticate by retyping the PIN or touching the sensor more than once before the user’s fingerprint is accepted.
At the same time, the security offered by the fingerprint recognition systems generally implemented in phones is at least equivalent to that of a minimum four-digit PIN, or even the recommended six-digit PIN. This is deemed sufficient by phone manufacturers to protect the value-at-risk of a smartphone and of the data it holds.
