Delete apps and data from your device
The only sure way to protect data from a border agent is to delete it from your device. We recommend using erasing software that completely wipes data so that it cannot be recovered later. Be sure to back up your data first using a secure cloud backup (or using an external storage device that is not traveling with you).
erase/wipe, because deletions are trivial to recover, and will be, when initial scan of phone doesn’t provide as much info as they want or expect it to.
In the US, border agents are only allowed to access data on the device itself, not cloud data. Therefore, to avoid inadvertently accessing remote data, they are required to ask you to set your device to airplane mode (or they may do it themselves in some circumstances).
This I did not know, although I’d still have no trust they wouldn’t toggle airplane mode off.
How about using a burner phone and special accounts that are only used during your stay?
Why should you continue using any device that you gave to third parties without knowing what they did with it? Border agents etc. could easily install malware or extract device information.
even better,heh, then you could hand it to them and say keep it, I’ve got a plane to catch…