I assume they confiscated his computer, wouldn't they know what randomizer/algorithm he used? Surely he had a way to quickly decrypt the data.
Seagate has a USB disk that they guarantee to be uncrackable. It uses a simple short password that the user picks. It scatters the data across the disk, and it can only be retrieved by a small program on the disk that destroys its own allocation table if a wrong password is used too many times.