🚀 go-pugleaf

pmetzger@snark.shearson.com (Perry E. Metzger) writes:
: 
: If "standard" means analog, well, analog phone scramblers are almost
: all easily broken, and are pretty poor in general. Why use one when
: digital techniques that are virtually unbreakable are available?

How is this done in the case of randomly hopping variable split band
spectrum inverters?  Current technology allows hopping between any of
32 frequency split points at a 60 hz hopping rate.  From 16.67 ms
fragments how on earth does one gather any information as to its
content or split point?  According to Micheal Washvill a voice and
data security specialist with a "federal agency":

	VSB scrambling can be broken but not in real time. The only
	practical attack is through trial and error.  The scrambled
	speech must first be recorded, then divided into finite time
	segments according to the hop rate.  Each segment is processed
	through a variety of split points until clear speech results."

He claims a 60 to one decode time.  Gimme a break!  Who decides when
clear speech results?  Automatic speech recognition is nowhere near
capable of this which leaves a human to determine what is clear
speech.  Think of the combinatorics here to decide on a second!  Does
it actually seem reasonable that this could be done in finite human
time or is this guy blowing self serving smoke to discourage its use?

Or are there more sophisticated methods?  I have some experience in
signal processing and in speech recognition and certainly can't think
of one.  I've seen the statement that it is easy but I'd sure like to
see that backed up with an algorithm.

Bob

Bob
-- 
Bob Cain    rcain@netcom.com   408-358-2007

        "One can learn to be alone, even enjoy it, but let intimacy
         break that solitude, even briefly, and one must start all
         over again."

                                                     Elia Kazan


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