Path: cantaloupe.srv.cs.cmu.edu!das-news.harvard.edu!ogicse!usenet.ee.pdx.edu!pdxgate!rigel!tauren
From: tauren@rigel.cs.pdx.edu (Tauren N Mills)
Newsgroups: sci.crypt
Subject: Thoughts and questions
Message-ID: <7325@pdxgate.UUCP>
Date: 23 Apr 93 00:43:07 GMT
Article-I.D.: pdxgate.7325
Sender: news@pdxgate.UUCP
Lines: 35

I just joined this group recently and really do not know much about
cryptography, but a couple things came to mind while reading through
the posts.

1.  Is the Clipper chip going to be exported?  If not, how will
people communicate with other countries?  Will they have to do
that in un-crypt-mode.  Will other encryption techniques be
legal (assuming the government cracks down on using others) when
going overseas, but not within the states?

2.  I've read about authentication systems that use an electronic  
security card that looks like a calculator to create an encrypted
PIN based on the time/date.  The host system has the algorithm
built into it as well so that it can authenticate a user.
Is there some form of encryption technology that would create
keys that are only valid at a certain instant in time?  The 
systems would then allow a "window" of time around this instant
where the key would work.
I realize that this technique would increase the amount of information
needing to be stored because you would need entire algorithms rather
than just keys.  But for smaller scale things it might work.
Could some similar method be used to make the two 80-bit keys that
are issued to police/FBI/etc to tap a phone only usable for one-week
(for instance).  If further surveilance was needed, they would have
to go back to the escrow service to get another key.  This would
make it useless for local police to database keys they have used.

I assume this is not possible because the receiving phone would need
to be able to decypher the message.  But any thoughts on the subject?

Thanks,
Tauren Mills

Tauren Mills
tauren@rigel.cs.pdx.edu
