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Cider9986

Not physically possible[1] to be deniable and a bad[2] idea.

[1] https://veracrypt.io/en/Wear-Leveling.html

https://veracrypt.io/en/Trim%20Operation.html

[2] https://nitter.net/GrapheneOS/status/2082153517234676150#m

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I don't understand how wear leveling makes deniability impossible. You just have to overwrite sectors in the false partition at the same rate as ones in the true partition. Since both the true and false partitions are encrypted, their contents are mathematically indistinguishable from randomness when viewed without the decryption key.

I also wish that GrapheneOS link didn't say a duress PIN forces the attacker to think twice about entering a PIN, knowing it could wipe the device. It doesn't do that for anyone aware of its existence, since of course the attacker can prevent the secure element from sending a delete command to the flash chip. Obviously if you know the device could attempt to delete itself you would break that feature before sending the code to the secure element...

> I don't understand how wear leveling makes deniability impossible. You just have to overwrite sectors in the false partition at the same rate as ones in the true partition. Since both the true and false partitions are encrypted, their contents are mathematically indistinguishable from randomness when viewed without the decryption key.

With deniability, isn't the idea that you would have unlocked the false partition to show that you have nothing on your phone, therefore it's not encrypted?

There's no way to prove the second partition is real encrypted data instead of random garbage. It gets wear-leveled but that would also be the case if the true partition had been resized before.

It doesn't matter if the false partition is unlocked or not - you can plausibly deny there's anything on the phone at all.

Deniable encryption mixes more poorly with SSD wear leveling than you believe it does.

The secure element has built-in storage protected against tampering. It doesn't rely on external storage. Having support for the duress PIN/password built into the secure element rate limiting would force an attacker to risk wiping it unless they have a secure element exploit. If they have a secure element exploit then they don't need any attempts for a typical PIN since they could quickly brute force it. That's the planned design of the feature once we have the ability to extend the secure element functionality.

If they can exploit a secure element then only a decent passphrase is secure. GrapheneOS does make using a decent to strong passphrase much more convenient and memorable but it isn't what most people use in practice.

Question on a detail: It's not necessary to have deniability on the fact that you did wipe your device, just on the fact that you did it after you entered the border? Or said differently, if he'd wiped the device before entering the border, it'd be all fine?

(That of course only takes down the "physically impossible" part.)

I do believe that yes, if it was wiped before entering, there would be no charges (unless there was a shadow docket open... that gets murky)

Hence why travelers should simply not cross the border carrying sensitive data, ever. The Internet can take that data across the border for you.

I think you are vastly overestimating the amount of analysis that border guards are capable of.

Once it's a known feature, analysis finding out about it would be added to commercial forensic tools. Given the first two links, simply hooking up a computer to the unlocked phone would allow Cellebrite to give border guards the information that you are using a hidden partition in a user friendly UI.

For example, documents like this[1] document any features that law enforcement should be aware of.

[1] https://www.swgde.org/wp-content/uploads/2025/09/2025-08-21-...

You don’t need it to delete anything, anyway. The encrypted second partition is indistinguishable from random data, so you don’t need to delete it.

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