From: clary@iastate.edu (Jeffrey S Clary)
Subject: Re: radio waves as public property
Organization: Iowa State University, Ames IA
Date: Fri, 22 Jan 1993 17:22:16 GMT

I'm obviously not communicating very well here.  If any computer science
theoreticians (my work is usually leans to the applied side) would like to 
come to my aid, feel free.  Perhaps in this conversation looser definitions 
will do, but "encryption" implies things that "encoding" does not.  I may 
also be butchering the technical definitions.

All communication involves some form of encoding.  Do you think that all
communication involves encryption...that is, that the two words have
identical meanings?

Consider this.  An encoding, say printed English, that is well known in
the community is worthless for sending secret messages.  However, those
messages can be encrypted, say using Data Encryption Standard (DES) and
a key known only to the sender and receiver.  A hostile in between can
know English and have a full specification for the DES encryption process,
but still probably can't read intercepted messages without knowing the key
(or spending a huge amount of resources guessing it).  Furthermore, any 
number of sender/receiver pairs can use the same DES algorithm to encrypt 
their messages with different keys.  If it helps, think of the key as a 
characteristic of the message sent, not part of the encryption process.

In <1jnbe9INNobv@transfer.stratus.com> cdt@sw.stratus.com (C. D. Tavares) writes:

>In article <clary.726938330@pv031e.vincent.iastate.edu>, clary@iastate.edu (Jeffrey S Clary) writes:
>> >Just because a code is well known doesn't mean it's not still a code.

Oops.  Missed this the first time.  I am not saying that radio waves or
English are not encodings...just that they are not encryptions.

>> Guess we'll just have to disagree on terms here.  I am speaking from a computer
>> science perspective, where encryption does indeed carry the connotations I
>> mentioned above.  Would you consider the English language an encryption?  

>Under your definition? :

>>> Encryption implies encoding
>>> information in such a way that, with a piece of data presumably known
>>> intended receivers (a key) the message can be decrypted easily, but without 
>>> that key the message can only be decrypted with great computational expense.

>It is to many immigrants, as theirs are to me.  Would you consider the Navajo 
>language an encryption?  It was used VERY successfully as one in a FORMAL
>MANNER during WWII.

I heard this on NPR a while back...it was fascinating.

No, I wouldn't consider it an encryption, because it lacks the concept
of a key that is necessary to decrypt messages.  Perhaps you could
consider "ability to speak Navajo" as the key...but this is clearly
different than the arbitrary key used with DES.  The Navajo language is
analogous to the DES algorithm itself.  You can provide your antagonist
with full knowledge about the DES algorithm, and he still can't read
your messages unless he has the key.

>> I would think that any being who intercepts Explorer (or was it Voyager?)
>> would have as much trouble decoding an actual audio message in English as
>> they would a video disc.

>Well, thanks for arguing my side.  (And you're right, it WAS Voyager.)
>--

>cdt@rocket.sw.stratus.com   --If you believe that I speak for my company,
>OR cdt@vos.stratus.com        write today for my special Investors' Packet...

BTW, since it was a while back, I'll repeat this.  I am against any
restrictions on anyone receiving and reading broadcast messages, encrypted
or not.  The sender/receiver should shoulder all of the risk for their
choice of encryption method of secret messages.
-- 
**************************************************************************
* "Rub her feet."  --  L.L.                          * Jeffrey S. Clary  *
*                                                    * clary@iastate.edu *
**************************************************************************