From: lmccarth@cs.umass.edu
Date: Mon, 5 Feb 1996 12:49:26 +0800
To: cypherpunks@toad.com (Cypherpunks Mailing List)
Subject: Re: RC2 protected by copyright?
In-Reply-To: <199602050211.SAA18120@hammerhead.com>
Message-ID: <199602050413.XAA05802@opine.cs.umass.edu>
MIME-Version: 1.0
Content-Type: text/plain


(IANAL, and I'm not even attempting a lay interpretation of the _legal_ 
issues in this message)

thad writes:
> But, what about copyright?   Now, copyrights cannot protect ideas, only
> the expression of those ideas.  An algorithm is clearly an idea, you could
> write a program that would implement it in a completely different way,
> not just by translating it (translations are still protected by
> copyright). 
> 
> RC2, though, as 256 bytes of seemingly random data at the head of it,
> in a permutation table.  This is clearly not any idea, but a bit of
> text.  This text would have to be copied to any interoperable RC2.
> (You could surely use some different permutation, and probably most
> of the 256! permutations would be equally secure, but would not
> interoperate with RC2).  I would expect that this copying of text be
> held to be a violation of copyright.

>From a technical perspective, I can't say that the permutation table is
"clearly not an idea", although that view has some significant allure.
I think many cryptographers would agree that the S boxes in DES represent 
some pretty weighty ideas indeed, and constitute an intrinsic part of the
algorithm. Offhand the precise construction of the RC2 permutation table
doesn't seem to me to be nearly as important to the strength of RC2 as the
S boxes are to DES' strength. I'm certainly no expert. But I'm a little 
hesitant to dismiss the specified table as "a bit of text". 

Do you think the table would be more like an idea if it turned out to be
determined by pi ?  (not a rhetorical question)

-Lewis <lmccarth@cs.umass.edu>		`I went down to the demonstration/ 
to get my fair share of abuse/ singing we're gonna vent our frustration/
if we don't, gonna blow a 50A fuse" -Nanker Phelge