Fingerprint scanning is an easy and fast way to unlock mobile phones and authenticate identity to supported applications. Many banks have already added support for this capability and are allowing their customers to log in to mobile banking apps by scanning a finger instead of entering a password.
The initial impact was immediate. Millions of users enrolled in fingerprint authentication and started logging in without using passwords. The user experience improved, and security seemed to be better, because, unlike passwords, fingerprint data is locked on the device and can't be easily stolen or phished.
Over time, however, security and usability issues started to emerge. The first problem occurs when users switch to a new phone. When users download a bank's app to their new phone, they are required to enter their password again during the first login. There is a technical explanation for this requirement, which I'll describe shortly.
First, let's consider the usability and security impact of re-entering a password on the new device. Many users who have become accustomed to logging in with their fingers are less likely to remember their password. Therefore, when the app forces them to enter a password, many will have to initiate a "forgot my password" process. This often involves contacting the bank's call center, which affects the user experience. There is also a security implication attached to this process. Even if they're not being used to log in, passwords still exist in the background. Therefore, they can still be stolen or phished by fraudsters to take over an account, even if the user is using fingerprint authentication.
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Now for the technical explanation. Fingerprint information is managed by the mobile device's operating system. It's stored on the device and never leaves it. When a user enrolls in fingerprint authentication for a specific app, such as the banking app in our example, the app links the user's identity with the fingerprint information stored on the device. Therefore, when a user replaces his or her device and downloads the app to the new one, the app has no way of verifying the owner's fingerprint because that data was stored on the old device. To validate the user's identity and link a fingerprint to the new device, the app falls back to password authentication.
This problem isn't limited to new devices. There are other scenarios in which the link between a user's fingerprint and the mobile app can break (for example, if the user adds fingerprints to the device or removes them). As a security measure, the operating system breaks the link in this scenario and the user is forced to re-enter a password. This is a security function that many sensitive applications, such as banking applications, have implemented. Other scenarios include when a user resets the device to its factory settings or reinstalls the app.
Fingerprint authentication is a good first step for avoiding passwords, but it doesn't eliminate them. This partial measure, as described above, can create a bigger password problem. In order to truly get rid of passwords, we need to address and remove the scenarios (and others like them) described earlier. This involves implementing processes and technologies to bridge these gaps. Some alternatives include the use of challenge questions, one-time-passwords, voice biometrics, touch biometrics, and other technologies that need to be constantly orchestrated to create a password-free experience.