From: dougb@comm.mot.com (Doug Bank)
Subject: Re: REVISED TECHNICAL SUMMARY OF CLIPPER CHIP
Reply-To: dougb@ecs.comm.mot.com
Organization: Motorola Land Mobile Products Sector
Nntp-Posting-Host: 145.1.146.35
Lines: 53

In article <1993Apr21.192615.3465@guvax.acc.georgetown.edu>, denning@guvax.acc.georgetown.edu writes:

|> The chips are programmed by Mykotronx, Inc., which calls them the
|> "MYK-78."  The silicon is supplied by VLSI Technology Inc.  They are
|> implemented in 1 micron technology and will initially sell for about
|> $30 each in quantities of 10,000 or more.  The price should drop as the
|> technology is shrunk to .8 micron.

Hmmmmmm.  $30 seems a bit expensive.  How big is the chip?  What kind
of packages will be used?  3 volt or 5 volt technology?  How much
current will it draw?  I think there are many practical questions
that haven't been answered, especially since this chip already exists!

|> All Clipper Chips are programmed inside a SCIF (Secure Compartmented
|> Information Facility), which is essentially a vault.  The SCIF contains
|> a laptop computer and equipment to program the chips.  About 300 chips
|> are programmed during a single session.  The SCIF is located at
|> Mykotronx.
|> 
|> At the beginning of a session, a trusted agent from each of the two key
|> escrow agencies enters the vault.  Agent 1 enters a secret, random
|> 80-bit value S1 into the laptop and agent 2 enters a secret, random
|> 80-bit value S2. These random values serve as seeds to generate unit
|> keys for a sequence of serial numbers.  Thus, the unit keys are a
|> function of 160 secret, random bits, where each agent knows only 80.

OK, I've got a big problem with all of this.  How in the world do you
expect to sell these chips for even $30 after all the overhead involved
in this programming procedure?  2-4 people, a laptop, only 300 chips at 
a time:  give me a break.  And how long does all of this take?  Even if
it is a minute per chip, it will take the greater part of a day to 
turn out 300 of these things.  How long do you suppose it will take to
program those 10,000 chips mentioned above?  This is highly impractical!

|> To see how the chip is used, imagine that it is embedded in the AT&T
|> telephone security device (as it will be).  Suppose I call someone and
|> we both have such a device.  After pushing a button to start a secure
|> conversation, my security device will negotiate an 80-bit session key K
|> with the device at the other end.  

So where can I find info on this AT&T device?  What kind of vocoder
does it use?  Does it require ISDN phone lines?  If not, is it full
duplex?  How does it sound?  What kind of synchronization scheme is
used?  Will all other little black boxes have to conform to AT&Ts choices
of protocol, etc.?  Will anybody else be allowed to build boxes that
conform to these specifications?


-- 
Doug Bank                       Private Systems Division
dougb@ecs.comm.mot.com          Motorola Communications Sector
dougb@nwu.edu                   Schaumburg, Illinois
dougb@casbah.acns.nwu.edu       708-576-8207                    
