[136] in cryptography@c2.net mail archive
re:Secure Phones
daemon@ATHENA.MIT.EDU (C. Kuethe)
Mon Feb 3 14:35:21 1997
Date: Mon, 3 Feb 1997 12:19:15 -0700 (MST)
From: "C. Kuethe" <ckuethe@gpu.srv.ualberta.ca>
To: Cryptography <cryptography@c2.net>
My guess on the CESCOMM device is that they (would like us to belive that
they) use pure RSA with optional hybrid links... this seems a bit obvious
because of:
"Guessing the unique Keys is out of the question. Acquiring the keys through
wiretapping is impossible, since they are never transmitted." <--RSA?
"Secure modes can be changed with either a reset button or the insertion of a
key. This includes a session code which allows multi-party conference calling
for all those parties with appropriate Session Keys." <--conventional...
Odd.... if keys are never transmitted, how do you [en|de]crypt? Maybe there
are a few keys hardwired in... :(
I emailed the German team about the LC-1... don't know if I'll hear back from
them, but if I do, I'll pass on everything I get.
the third system scares me... "Analog voice scrambling" it says on the main
page... and then the specs page says:
Encryption Key Management
* Key length: 127 bits
* Key management: Automatic key exchange, one-way cipher function
* Private key generation: Thermal noise generator
Voice Scrambling
* Primary scrambling method: Key based sub-band scrambling, 24 active bands
* Second: Key based re-scramble once per second
* Third: Key based spectral inversion of selected sub-bands
* Secure mode voice pass band:200 Hz - 3130 Hz
So maybe it's not just some funky analog signal processor, but if the system
only encrypts 200-3130 Hz, I'd think there's some data leaking out there...
I suppose they assume it's because there's not a whole lot of voices outside
that range, but I know that when I speak I produce a fair amount of sound
below 200Hz.... are we all supposed to talk like Mickey Mouse while using this
device? :(
Just my little rant....
PLUR
chris
--
Chris Kuethe <ckuethe@gpu.srv.ualberta.ca> LPGV Electronics and Controls
<c100305@wolfcreek.cs.ualberta.ca> http://www.ualberta.ca/~ckuethe/
RSA in 2 lines of PERL lives at http://www.dcs.ex.ac.uk/~aba/rsa/
print pack"C*",split/\D+/,`echo "16iII*o\U@{$/=$z;[(pop,pop,unpack"H*",<>
)]}\EsMsKsN0[lN*1lK[d2%Sa2/d0<X+d*lMLa^*lN%0]dsXx++lMlN/dsM0<J]dsJxp"|dc`
