I recently committed an extension to dwsCrypto lib module that exposes direct support for cryptographic nonces and tokens.
Time for some summer fun! Someone asked in the delphi win32 newsgroup how to prevent users from doing a “Print Screen”. The answer to that is that you can’t really, since screen capture can be invoked from other applications, or your app can be hosted in a Virtual Machine, accessed over RDP, or a frame can be grabbed directly from the screen cable.
However all hope is not lost! Even if you can’t defeat a “Print Screen” or screen capture, it’s possible to make such a capture useless.