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How Do I Prepare My Phone for a Protest?
(themarkup.org)
This is a most excellent place for technology news and articles.
They may confiscate your phone and record all data on it.
If it's a fresh wipe with a good passcode, and you keep it on airplane mode, you're probably fine.
Set up a duress PIN on your graphene phone
Graphene is not a good OS for this type if work. Yes it's secure, no good backup solutions. You will lose all your data upon confiscation. Graphene again is secure but if all your data is gone what good will it do? DO NOT TAKE YOUR PERSONAL DEVICES.