Pattern lock: draw to open your vault
Backroom opens with a pattern on a 5 by 5 grid, separate from your iPhone passcode. How strength works, and what a pattern can and cannot stop.
You open a vault by drawing a pattern of at least 6 dots on a 5 by 5 grid. The pattern is separate from your iPhone passcode. It runs through a slow key derivation to unlock your vault's key, so there is no stored copy of it to find. Longer patterns with more turns are stronger, and Backroom rates each one when you make it.
Your phone’s passcode protects a lot, and often more people know it than you intended. Backroom asks for something different.
How it works
You draw across a 5 by 5 grid of dots. Backroom needs at least 6 dots and shows a strength rating when you create a vault. A weak pattern gets a warning, and the app leaves the final choice to you. In Settings, you can turn on Hide the line while drawing so that someone looking over your shoulder sees less.
The pattern is turned into a key using PBKDF2-HMAC-SHA512 with 1,000,000 iterations, along with a salt stored in the Keychain on your device. A wrong pattern gives no specific error, because the app simply fails to find a matching vault.
What makes one strong
- More dots, well beyond the minimum
- Plenty of direction changes
- Nothing that looks like a letter
The pattern strength tool lets you try ideas on this site. Do not enter the one you plan to use.
Limits
A pattern holds less randomness than a long password. There is no hardware limit on guesses like your iPhone’s passcode has, so the app slows guessing through the key derivation alone. Someone with a full extraction of your phone, including its Keychain, could try guesses offline. A long pattern buys you much more time. This comparison goes further.
You can change a pattern at any time in that vault’s Settings.
Frequently asked questions
How many patterns are possible?
At the 6-dot minimum, up to about 127 million ordered patterns. Real choices tend to cluster, so aim for more dots and more turns.
Does it use Face ID?
No. Vaults open with a pattern or recovery phrase only. Your passcode and Face ID do not open them.
What if I draw a pattern it does not recognize?
You see a screen offering to make a new vault with that pattern, or to draw again. The text is the same on every phone, and it gives no sign of other vaults.