Similarly, if you’re in a situation where you cannot guarantee your phone’s security because it’s leaving your possession, and you’re sufficiently worried, again, power off fully.
Similarly, if you’re in a situation where you cannot guarantee your phone’s security because it’s leaving your possession, and you’re sufficiently worried, again, power off fully.
This is a terrible idea. When you're crossing a border you have to submit to the rules of entry. If one of those rules is that you let them create an image of your phone with all of its contents, that's the rule. If you say no, then, if you're lucky, you get to turn around and return to where you came from. If you're not lucky, then you get to go to jail.
What needs doing is the ability to make a backup then a way to reconcile the backup at a later date with the contents of a device. That is, I should be able to backup my phone to my home computer (or cloud I guess) and then wipe my phone or selectively delete contents. Then I travel abroad, take photos and movies, exchange messages with people, and so on. Then when I get home I should be able to restore the contents of my phone that were deleted without having to wipe all the new stuff from the trip.