Security / Drawing a pattern in public

Is it safe to draw a pattern in public?

Short answerIt's safest not to. A well-chosen pattern can be much harder to guess than a 6-digit PIN, but someone watching, or a camera, can copy it. If people can see your screen, cover it with your hand, turn away, or wait until you're alone. If you think someone saw it, change it.

The real risk

Watching is a different problem from guessing. A good pattern beats guessing because there are so many possible ones. But if someone sees you draw it, they don't need to guess. They only need to remember a shape, and shapes are easy to remember.

In one online study, people watched video recordings of someone entering an unlock code and tried to work it out. After a single viewing, they got a 6-length Android pattern right 64.2% of the time. They got a 6-digit PIN right 10.8% of the time. After watching more than once, those rose to 79.9% and 26.5%. The study used Android patterns, not FirstHour's 5×5 grid, so the numbers won't match exactly. We don't know of a study of FirstHour's grid, but the lesson carries over: a pattern is easier to copy by watching than a PIN.

The risk has two parts. Someone has to see you draw it, and then they have to get hold of your iPhone. Waits and encryption help against guessing. They can't help once the pattern is known.

How to draw it privately

What FirstHour does

When you draw your pattern, FirstHour draws a line as you move between the dots, and the line fades after each try, so it can't be read off the screen later. It does nothing about someone who is watching while you draw.

Privacy Display, in Settings, is a different thing. It covers your pictures in the recent-apps view, hides every picture in FirstHour while your screen is recorded, mirrored or shown on AirPlay, and locks the Vault while that happens. It does not hide the dots from a person standing next to you, and it can't stop someone photographing your screen with another phone. Here's what each switch does.

The Vault also locks when you switch tabs or leave FirstHour, so a Vault you've opened doesn't stay open behind you. While it is open, anyone looking at your iPhone sees what you see.

When a PIN may suit you better

FirstHour lets you pick either. Here's how they compare, and how to choose.

If you think someone saw it

  1. Change it when you're alone. Open the Vault, tap •••, then choose Change PIN or pattern. Pick a new one that isn't a small variation of the old one.
  2. Keep the same kind if you have a decoy vault. Switching between a pattern and a PIN removes the decoy and the pictures in it.
  3. Keep your iPhone with you. The pattern only matters to someone who can reach the phone.
  4. Check your recovery phrase is private. Keep it private, somewhere nobody else looks. Here's how the phrase works.

Waits after wrong tries don't help against someone who already knows the pattern. They only slow down guessing.

What this can't fix

Questions

Does Face ID make this easier?

Face ID opens FirstHour's app lock, but it can't open the Vault. The Vault always needs your pattern or PIN, so shielding it still matters.

Is a longer pattern harder to copy?

It's harder to guess, but we don't know of a study showing it's harder to copy on a 5×5 grid. Shielding is what helps.

Sources

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