Hi Bernardo; TEMPEST isn't a cipher, but a technique. Essentially, your monitor is a great big RF emitter. As it's electron gun turns off and on to make the phosphor screen glow, it's emitting all kinds of radio frequencies that betray the image on the screen. A tempest attack is a receiver that can tune to a monitor, and reconstruct the image from the RF the monitor is emitting. Supposedly such equipment costs about $500.00 Harvey "Know it All" Rook.

-----Original Message----- From: Bernardo B. Terrado [mailto:bbt@mudspring.uplb.edu.ph] Sent: Tuesday, September 08, 1998 11:03 PM To: cypherpunks@toad.com Subject: question...

What is the TEMPEST? (just an overview)

What do enciphered images look like?

Thank you.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~~~ Some people they might say that I'm hard to get to know. I go my own sweet way, well that maybe so. Something about the crowd that makes me walk alone. I never had a need in me to be the party's life and soul.

It's me Bernie. metaphone@altavista.net `````````````````````````````````````````````````````````````` ````````````````