From: Robert Schrader (rms@cts.com)
Date: Fri Mar 21 1997 - 13:01:56 MST
On Thu, 20 Mar 1997, Hal Finney wrote:
> {snip} [ Trusted computers ] are computers which you own but which
> are trusted by other people! The computer works for somebody else, not for
> you.
>
> The idea is that you load some software (or a book, video, etc.) into the
> computer and it lets you run it, but it won't let you copy it to anybody
> else. Or, you can loan it out but when you do you don't have it any more.
These can be circumvented rather easily. I've done it. ( Not for theft,
but for speed. I've got a slow 1xCD but a fast hard drive. )
A TSR is put in upper memory. It prempts the keyboard interrupt, steals
commands from the keyboard buffer that are meant for it, possibly adds
a few, then passes control to the keyboard interrupt routine. This
allows it to simulate keyboard input. So with one keypress from the
computer owner, lots of commands - such as 'turn page' - are generated.
The trusted program spills its guts.
The TSR also evesdrops on the screen writing interrupt, and copies everything
to a file.
If too many one-time books/videos are on the market, then somebody ( not
me ) will write a program like this and pass it around.
Robert Schrader rms@cts.com
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