From: Bill Sommerfeld <sommerfeld@orchard.medford.ma.us>
Date: Sun, 18 Apr 93 17:37:05 PDT
To: karn@qualcomm.com
Subject: Followup message from Hellman
In-Reply-To: <9304182047.AA03182@servo>
Message-ID: <9304190011.AA00158@orchard.medford.ma.us>
MIME-Version: 1.0
Content-Type: text/plain


Quoting Martin Helmann as forwarded by Steve Belloving and Phil Karn:

   she [Denning -sommerfeld] says the message is not double encrypted.
   The system key (or family key as she was told it is called) only
   encrypts the serial number or the serial number and the encrypted
   unit key. This is not a major difference, but I thought it should
   be mentioned and thank her for bringing it to my attention.

This sounds pretty unlikely to me -- if the message isn't
double-encrypted, the "tags" could be separated from the ciphertext
without too much effort.  Of course, it's not clear whether the
receiving system checks the serial number, or whether the serial
number is factored into E[M;K]; conceivably, those things could be
reconstituted on the other end if the receiving wiretap chip needed
them..

					- Bill