Actually, all you need to do is make sure your iCloud backups are up to date before you hit the border checkpoint.
Then, perform a factory reset, and wipe your iPhone clear and clean.
Cross the border – if they stop you and ask for your iPhone, hand them the factory reset and wiped iPhone.
With a smile.
When you get home, just restore your iPhone with the iCloud Backup.
Rinse and Repeat.
A few months ago I wrote about how you can encrypt your entire life in less than an hour. Well, all the security in the world can’t save…