A method for protecting the video memory on a computer system from being
illicitly copied. The invention decrypts a previously encrypted image and
displays it on the video screen. During the time the image is displayed,
the invention protects it from being copied by other running
applications. This is accomplished in multithreaded operating systems by
first issuing a multithreaded locking primitive to the video memory
resource, and then inserting a pending video hardware request that will
take precedence over any subsequent video memory access requests. The
pending request serves the purpose of destroying the contents of video
memory. The pending request is passive in that it does not execute unless
a malicious program has removed the video memory lock.