Beat Remote Monitor Snooping?

I know that monitors emit RF signals that can be detected and decoded for a
considerable distance.  I have a question about this.  Obviously, the
difference between black and white (white text on black background, or vice
versa) would be the most detectable, because the difference in signal levels
would be the greatest.  Would it be possible to reduce or prevent this kind
of snooping by using color schemes that all use the same signal levels?  For
example, the color purple uses the red and blue color guns, and yellow uses
the red and green color guns.  Would purple text on a yellow background be
able to be read by a remote snooper?  If not, then perhaps these color
schemes could be used to echo pass phrases--assuming the user isn't worried
about someone looking over their shoulder.  Any comments?

Jonathan Wienke

Visual contrast is not the same thing as frequency diffrence. It is quite
easy to measure extremely small changes of phase.  As in, your
plain-vanilla FM receiver. What's his name put this stuff together in the
mid 1930's. 

Nice try, but no cigar.

Can you please take me off your mailing list.  Thankyou.
firebrd123@mail.interconnect.net

Firebrd123 writes:
> Can you please take me off your mailing list.  Thankyou.
> firebrd123@mail.interconnect.net

No, we can't take you off the list. We are the *recipients* of the
mailing list, not the people who run it. We have no access to the
machine that contains the list management software. You get off by
mailing to the same address you mailed to to get on. I leave that
information as an exercise to the reader.

>>>>> Alan Horowitz <alanh@infi.net> writes:

  > Visual contrast is not the same thing as frequency diffrence. It
  > is quite easy to measure extremely small changes of phase.

Apropos of *what*?!  If it was an NTSC colour TV; yes, you could
measure the colour by the phase of the 3.579 colour burst.  But modern
computer monitors (i.e. VGA) don't represent colour that way at all --
they use separate red, green, and blue video signals.  And the
original poster is correct -- it is extremely difficult to determine
which guns are generating any given pixel, using van Eck monitoring.

The only com/mil ELINT demo I've ever seen of a VGA monitor generated a
greyscale display.

  > Nice try, but no cigar.

If the shoe fits...

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