The key part here is that passwords, the vulnerable part of a users log in, become redundant.

Your smartphone has become considerably more valuable with every new authorisation from your device, not just because of this test.

Google confirmed this morning it’s now testing a new way to sign into your Google account without having to type in a password. Instead, those who have been invited to try this new method of logging in authenticate by responding to a notification sent to their smartphone. The idea is similar to Yahoo’s recently launched “Account Key,” which also offers a password-free means of signing in involving a push notification sent to your phone that then opens an app where you approve the log-in. Google Tests Smartphone Authentication To Log In to Your Account [techcrunch.com]