Duress password.

A second password that opens a harmless decoy instead of your real vault. It exists for the moment you are made to unlock your device: you enter it, an empty vault opens, and nothing reveals that a real one was ever there.

// definition

A duress password, also called a decoy or plausible-deniability password, is a credential that opens a decoy view of an app while hiding or destroying the real data. It protects against coercion, where an attacker can compel you to unlock but cannot tell a real unlock from a decoy one.

What it is

Ordinary encryption protects a vault from someone who does not have the password. A duress password addresses a different threat: someone who has you, and can make you enter a password. The defense is not a stronger lock but an indistinguishable one. The real password, the duress password, and a wrong password all behave the same way, so there is no state an observer can read to know which was used.

Why it matters

At a border, a checkpoint, or under pressure, refusing to unlock can be its own signal. A duress password lets you comply and still give nothing away. It is not a universal shield: it does nothing about a copy of your storage taken beforehand, and it cannot cover traces left in backups or other apps. It handles one specific situation, the forced unlock, and handles it well.

// in AgePony On Android, AgePony lets you set a duress password. Entering it opens an empty decoy vault and clears the real one, and biometric unlock is torn down so the vault is password-only afterward. Each password is run through scrypt to derive a different key, and the unlock does the same work whichever one it is handed, so the three cannot be told apart. It is destructive by design, so keep a backup. iOS has the full signing surface but not duress yet.

Related terms

Common questions.

Is a duress password the same as a decoy password?

Yes. Duress password, decoy password, and plausible-deniability password all describe the same idea: a second credential that opens something harmless.

Does using it destroy my data?

In AgePony, yes. The duress unlock clears the real vault as it opens the decoy, so keep a backup of anything you cannot lose.

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