Computer security expert Bruce Schneier has written about a supposedly fool-proof method of encrypting the entire hard drive of a laptop computer. That means that you can travel internationally without ever revealing the contents of your laptop to Customs or other officials anywhere you travel. Even you will be unable to access the information until some time after you arrive at your destination.
Best of all, you can do this without lying. Yes, when asked to decrypt the information you can honestly reply, “It is impossible for me to decrypt it.” For proof that you are not lying, you can even carry a (printed) copy of the instructions with you to show to any government official who questions why you cannot decrypt the contents.
If the Customs or other official seizes your laptop and keeps it, he or she or even that government’s teams of experts will be unable to decrypt your secrets. Even if the official keeps your printed instructions of how you encrypted the hard drive, the government’s teams of experts will still be unable to decrypt your secrets.
Of course, you can later obtain another computer (preferably a brand-new one) and restore your data via online (and encrypted!) backups.
It is a slightly kludgey method of securing your business and personal secrets but for anyone who legitimately needs to keep information private, this is probably the best method.
You can read Bruce Schneier’s method of keeping your secrets from anyone else at: https://www.schneier.com/blog/archives/2009/07/laptop_security.html.