A new app called Knock launched on Tuesday in the App Store. It allows you to sign in to your Mac by simply tapping on your iPhone, negating the need to enter your password.
Created by experienced web and app developers William Henderson and Jon Schlossberg, Knock makes a secure connection between your iPhone and your Mac using Bluetooth LE. The iOS app is paired directly with a corresponding companion app for OSX, so there is no worry of others being able to unlock your computer. You can see how it works for yourself in the video below.
The Mac application also comes with other functionality including the ability to manage authentications from the desktop. You can sever connections and create new ones, for example, if you lost your phone or upgraded to another model.
The app uses Bluetooth LE, as we mentioned above, so it not only uses very little power, but it is more than capable of functioning as a background process.
Knock is compatible with both of Apple's new iPhone models as well as iPhone 5 and 4S and is supported on the other end by the following Macs: 2011 MacBook Air or newer, 2012 MacBook Pro or newer, 2012 iMac or newer, 2011 Mac mini or newer, and the 2013 Mac Pro. The iPhone app requires iOS 7.