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From GrapheneOS official account:

Our duress PIN/password feature doesn't pretend that it can stealthily wipe the device. It properly implements what people expect it to do and does it safely. It isn't our role to choose how to use the feature including how to use it in a situation where there are potential consequences to it. We haven't implemented any features which are in any way specific to situations involving law enforcement. We aren't going to give people any legal advice on how to handle situations involving law enforcement. It isn't our role and does not make sense particularly since laws vary so much based on jurisdiction, context and how they're interpreted on a case-by-case basis. If people want legal advice, they should ask a lawyer for it.

It's not possible to provide anything close to plausible deniability for wiping profiles. A deleted profile leaves behind metadata proving it existed in the device encrypted and Owner profile encrypted storage. There are a whole bunch of different ways it can be shown that it existed. ADB can be easily used to identify a wipe occurred and when it occurred. The standard approach used by forensic tools is connecting via ADB and they can easily add support for detecting this. It would be easy for non-experts to figure out how to do it especially with the guidance of a decent LLM. It would put users at risk who believe they can perform a stealthy wipe despite it not being possible. We do not want to provide a feature which cannot come close to working properly.

Android's Private Space has a half-baked feature for hiding that the Private Space is enabled in the user interface for someone without access to the relevant unlock methods or ADB. There are multiple publicly known ways to identify a Private Space is enabled. These aren't treated as significant security vulnerabilities and fixes for it aren't backported to older releases. It isn't practical to cover all possible ways of detecting it even with the limited scope of only attempting to hide it in the user interface and not ADB. We don't plan to remove the feature but don't think it should have been implemented and wouldn't have done it ourselves.

If we implemented a half-baked deniable wiping feature then the flaws would be discussed in this forum, our issue tracker and elsewhere on the internet. It would quickly become known to LLM models, which would be able to assist with detecting it. It would be incorporated into standard forensic tools and guides. This is not an approach we want to take with GrapheneOS.

Our features need to work against adversaries aware those features exist. An adversary aware of the duress PIN/password existing doesn't have a way to tell it apart from a real PIN/password. They'll have to consider if a PIN/password provided to them could be a duress PIN/password even for users who don't use the feature. The feature is now going to be widely known about due to the news coverage and it's still going to work.

On future devices, we want to add duress PIN/password support to the secure element as part of the Weaver rate limiting so it can't even be bypassed with an OS exploit.