Many smartphone users remain wary of biometric authentication because they fear their fingerprints or facial data could end up in a large corporate database.
That concern is misplaced when it comes to the biometric unlocking systems built into modern phones and computers, according to The Washington Post technology columnist Rob Pegoraro.
Apple, Google and Microsoft have designed their systems so that biometric information is stored only on the device where it was originally registered. The data is kept in a protected part of the device rather than uploaded to the companies’ servers.
This is also why users have to register their fingerprints or face again when switching to a new phone, even if most other applications and settings can be transferred automatically.
Security researcher Rich Mogull, CEO of Securosis, told The Washington Post that he was not aware of any successful attack that had extracted usable biometric data from these systems.
Apple’s implementation provides an additional safeguard by tying the mathematical representation of a user’s biometric information to the specific device on which it was created.
Even if the information could somehow be extracted, Mogull said, it could not be used elsewhere to reconstruct the original fingerprint or face.
Biometrics can also protect against phone theft
Biometric authentication has another practical advantage: it reduces reliance on short and easily guessed passcodes.
Phones and password managers are unlocked frequently, meaning users may be tempted to choose simple passcodes if they have to type them repeatedly.
Apple and Google have also increasingly built biometric checks into their anti-theft systems. This can prevent a thief who has learned the victim’s passcode from using it alone to take control of the phone and associated accounts.
There are, however, situations in which temporarily disabling biometric unlocking may make sense.
In the United States, for example, legal protections surrounding passwords and biometric authentication are not necessarily identical when authorities demand access to a device.
The Electronic Frontier Foundation therefore advises people attending protests to consider disabling biometric unlocking beforehand and relying on a strong passcode instead.
Similar concerns can arise at international borders, where authorities may have broader powers to inspect electronic devices.
Both iPhones and Android phones allow biometric authentication to be disabled temporarily. Restarting an iPhone, Android device or Mac also forces the user to enter a passcode or password before biometrics can be used again.
Pegoraro argues that for ordinary daily use, however, the privacy risk associated with on-device biometric unlocking is far smaller than many users assume — while the security benefits are substantial.