You keep your iPhone with you all the time. Now you can use it as a password. You never have to open the app— just knock on your phone twice, even when it’s in your pocket, and you're in.
Knock securely communicates with your Mac using Bluetooth Low Energy, a new technology that draws very little power. Knock works with any Mac that supports Bluetooth 4.0 after installing a companion application.
Please remember that while this app can be entertaining, anyone in possession of your iPhone could unlock your Mac.
You can purchase Knock from the App Store for $3.99.
Read More [via 9to5Mac]