Right now, all you need to access WhatsApp Web is to scan a QR code with the phone you’re running WhatsApp with. This could change in the future, as the Facebook-owned messaging app explores another security option. And it involves your phone’s fingerprint scanner.
WABetaInfo made the discovery via the app’s submission to the Google Play Beta Program. From the screenshot taken, it looks like you’ll have to use the fingerprint sensor on your phone to proof it’s you before you can make use of WhatsApp Web.
That being said, there’s no indication as to if this is an additional privacy safeguard in addition to the QR code, or if it’s something that will replace it entirely. An option to have both, or choose which works best for each individual user, would be nice. But whether or not that’s the case, we’ll have to wait for the feature to go live to find out.
And the feature may go live sooner than the other features WhatsApp is testing. WABetaInfo reports that the feature was found in version 184.108.40.206 of the app. The current version is 220.127.116.11, which suggests it’s only a few updates away, the frequency of the updates not withstanding.