In message <[EMAIL PROTECTED]>, John Young write
s:
>
>This loops back to NONSTOP and the question of what may
>be the signatures and compromising emanations of today's
>cryptosystems which reveal information in ways that go beyond
>known sniffers -- indeed, that known sniffers may divertingly
>camouflage.
Again going back to "Spycatcher", Wright described a number of other
emissions. For example, voices in a room could modulate the current
flow through a telephone's ringer. (This was, of course, back in the
days of electromagnet-actuated ringers...) One can also find signals
corresponding to the plaintext superimposed on the output waveform of
the ciphertext, and possibly see coupling to the power supply. (One of
the rules I've read: "Step 1: Look for the plaintext".)
I've seen brochures for high-grade encryptors that speak of "red-black
separation" and separate power supplies for the two halves.
--Steve Bellovin, http:/www.research.att.com/~smb
