RE: Steganography

From: Harvey Newstrom (
Date: Sat Sep 29 2001 - 16:33:25 MDT

Ralph Lewis wrote,
> Codes are one thing. You still have the fields from the monitor
> and computer and these can be intercepted.

Quite true! This gets into the field known as tempest technology.
Keyboards and monitors project radiation which can be read remotely. Each
keystroke produces a different signature. It is easy to record these
remotely (even through walls) and simply use statisitcal analysis to
determine which keystroke corresponds to which letter. In English, "E" is
the most common keystroke, etc.

Even the minor power fluctuations of a CPU can be read on the powerline down
the street. CPU fluctuations are tiny variations on top of massive
fluctuations caused by appliances. It is possible to tell the difference.

Tempest protection requires lead shielding, special fonts and displays,
self-contained power supplies, etc. These requirements are standard in
military secure vaults where computer work is done such that it cannot be
monitored from outside. I have worked on projects that specifically tested
and broke such security for military applications. The above information
have been well-known for decades. More sophisticated techniques are being
developed all the time.

Harvey Newstrom <>
Principal Security Consultant, Newstaff Inc. <>
Board of Directors, Extropy Institute <>
Cofounder, Pro-Act <>

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