From: tcmay@got.net (Timothy C. May)
Date: Sat, 12 Aug 95 09:56:20 PDT
To: cypherpunks@toad.com
Subject: Re: Purple Boxes
Message-ID: <ac522afb01021004ad76@[205.199.118.202]>
MIME-Version: 1.0
Content-Type: text/plain


At 10:08 AM 8/12/95, Sauroth wrote:
>Actually quite a few hackers/phreaks have been encrypting phone
>conversations for a while.  Not by any complex mathematics but
>simple modifications to the phone frequencies...Don't have any
>sites handy but for those interested I'll look up some of my old
>material.  I'll also check a large compendium of boxes to see if
>Purple has been designated.  Anyone interested in box plans of
>different colors e-mail me.

And the  "simple modifications to the phone frequencies" points to why such
things are not "strong crypto."

At best, security through obscurity. At worst, self delusion.

It gets back to the threat model. If the threat model is interception by
the neighborhood kids, then schemes for frequency-hopping, scrambling,
"warbling," and PhasorPhone-like diddling are OK. If the threat model is
the local police department tapping one's phone, probably not enough, as
they likely can gain access to the E-Systems DigiTrac 6700 and trivially
unscramble the signal.

Long term, only robust, strong crypto works (Michael Handler's "civil
liberties through complex mathematics").

--Tim May


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