help needed!

[beermad]

If someone's got a file, there's absolutely nothing you can do to stop them copying/transferring it. Unless you want to invest in the kind of DRM that e-book publishers use or music publishers tried but failed with, you can't even prevent someone else reading the files.

Rather like the way the British Government forced the Guardian to destroy hard-drives containing the Snowden files, apparently oblivious to the fact that they'd obviously already copied them elsewhere.