Knock: a rhythm as your passcode

A knock only you would make

Knock makes a nine-beat rhythm of taps and holds your passcode, and it reads the shape of the rhythm, not its speed.

Think of the way you knock on a friend’s door: a few quick raps, a pause, one long one. Knock asks for something like that. Taps and holds, quick gaps and slow gaps, nine beats in all, anywhere on the screen.

Shape, not speed

The rhythm is judged by its shape. Knock it fast in a hurry or slow when you are tired, and it is the same rhythm, as long as the long gaps stay long next to the short ones and the holds stay holds.

That is also why it is worth knocking clearly. A rhythm that sits halfway between two shapes is hard for anyone to read, a person or an app.

When it isn’t sure

If Knock can’t read a rhythm with confidence, it asks you to try again and doesn’t count it as a wrong attempt.

So an honest knock that came out muddy costs you nothing but another go. A clear rhythm that isn’t yours is different: that one counts against you, like any wrong code.

Your rhythm becomes the passcode

Read this part before you choose Knock. Choosing Cryptex or Knock replaces your passcode with the word or the rhythm, and Sealed says first if that removes a decoy or duress passcode.

Behind the rhythm sits a plain nine-digit code, and the keypad can type it. Once your rhythm is set, Knock shows the nine digits it stands for on the keypad and asks you to keep them somewhere safe, because they open the vault if you can’t knock it. Write those digits down when you set the rhythm up, and keep them as carefully as the rhythm itself.

Making a good rhythm

• Give it a shape. Knock refuses a rhythm that is too even and asks you to add a slow pause or a hold.
• Avoid a famous beat. The first notes of a well-known song are the first thing a stranger would try.
• Make it yours. A pattern you already tap without thinking is easier to repeat than one you invent on the spot.
• Practice before you choose. The Knock page in Settings lets you knock as often as you like, and nothing you knock there is saved or counted.

Teaching it your knock

1. Open Settings, then Passcode & Unlock, and tap Lock Screen. Swipe to Knock.
2. Tap Use This Lock Screen. If you have a decoy or duress passcode, an alert says first which ones go.
3. Knock your rhythm, then knock it again to confirm.
4. Note the nine digits it shows you, and keep them somewhere safe.

Where Sealed helps, and where it doesn’t

It helps if you remember rhythms better than numbers, and it never punishes a knock it could not read. If Knock can’t read a rhythm with confidence, it asks you to try again and doesn’t count it as a wrong attempt.

It doesn’t do these things:

• Keep your old passcode. Choosing Cryptex or Knock replaces your passcode with the word or the rhythm, and Sealed says first if that removes a decoy or duress passcode.
• Add strength beyond the code behind it. Every lock screen style is another way to enter your passcode, so it changes how you enter it and not how many combinations it has.
• Stay quiet. Taps on glass can be heard in a still room, and a rhythm someone heard can be copied. Break-in alerts react only to wrong tries.