How does Knock work?
Knock is a pair of apps: one for your iPhone, and one for your Mac. The two apps create a private, secure connection with each other via Bluetooth Low Energy.
When you're near your locked computer, Knock for Mac detects your iPhone. After a few security checks, the ring around your avatar pulses green, letting you know your Mac is safe to unlock.
When you see the green ring light up, knock twice on your iPhone - just like you'd knock on a door - and Knock automatically enters your password.
The Knock Mac app lives in the menu bar:
When you first open Knock Mac, you'll be greeted with a Setup assistant that walks you through connecting your Mac and iPhone.
Once connected, you can 'select 'Require Touch to Unlock for this Mac' in the Knock icon bar menu to require TouchID to unlock your Mac. When this setting is selected, you'll receive a notification to 'slide to unlock your Mac'. Sliding this notification to the left and pressing the revealed 'Unlock' button will allow you to use TouchID to Unlock your Mac. This is optional and only recommended in high security environments.
If you have an Apple Watch, you'll receive a notification to your Watch that you can tap to unlock your Mac. You can also access the Knock glance and tap that to unlock or lock you Mac. And finally, you can also open the Knock Watch app and press on the computer screen to unlock or lock your Mac.
If my Mac knows my iPhone is there, why do I have to Knock?
In security speak, this is called a Signal of Intent. In regular words, knocking is a natural way to confirm you're ready to unlock your Mac. Since you can knock on your phone even when it's in your pocket or purse, knocking is a super low-effort way of avoiding those embarrassing "oh no what did I leave open on my Mac" moments.
Do I need to wake my computer before Knocking?
Yes. You must wake your computer before you can use Knock to unlock.
The reason for this is that we use you waking your Mac as an indicator that you intend to unlock your machine, which tells us to start listening to your phone's accelerometer. We want to use that sensor as little as possible since it's an expensive sensor to use from a battery life standpoint.
Without the indication of waking the display, we'd have to constantly monitor your accelerometer for knocks which would drain your battery at a disturbing rate.
How do I secure my Mac?
The best and most robust way to secure your Mac is to Lock the computer whenever it goes to sleep.
You can update this setting by going to System Preferences > Security & Privacy > General and selecting Require password "immediately" after sleep or screen saver begins.
Then, check your Energy Saver preferences that put your computer to sleep after periods of inactivity. Depending on the nature of your work, you may want a very short period while others may want longer periods. To update these settings go to System Preferences > Energy Saver and change the time period for Display sleep to something small like 1 minute. Since entering Computer sleep will make it take longer for Knock to connect, we recommend setting Computer sleep to a high value, especially when running on Power Adapter:
Finally, you can quickly lock your Mac through any of the following methods:
1) Close the lid if it's a laptop or press the power button
2) Click on the Apple in the menu bar and select "Sleep"
3) Use the built-in "Lock" button on the Knock icon
4) Assign a Hot Corner to "Put Display to Sleep" or "Start Screen Saver"
System Preferences > Desktop & Screen Saver > Hot Corners...>
Can I use Knock with more than one Mac?
Not at this time.
Can I use Knock on a shared computer?
In a way, yes! You can set-up Knock while logged in to your profile and it will work as intended as long as you do not log out. You can still securely put your Mac to sleep or lock your Mac otherwise. However, if you log out, or use fast switching, Knock will not work as apps cannot run in the background in these cases.
Then, when a new person logs in to the Mac, they can set-up Knock as long as they use a different iPhone. Once again, if the user simply puts the Mac to sleep or otherwise locks the Mac, Knock will work as intended for them as well.