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From: srt@duke.cs.duke.edu (Stephen R. Tate)
Newsgroups: comp.lang.pascal,sci.crypt
Subject: Re: Implimenting this system...
Message-ID: <10688@duke.cs.duke.edu>
Date: Tue, 24-Nov-87 10:24:10 EST
Article-I.D.: duke.10688
Posted: Tue Nov 24 10:24:10 1987
Date-Received: Fri, 27-Nov-87 22:14:44 EST
References: <291@caus-dp.UUCP>
Reply-To: srt@duke.UUCP (Stephen R. Tate)
Organization: Duke University, Durham NC
Lines: 21
Xref: mnetor comp.lang.pascal:538 sci.crypt:732

In article <291@caus-dp.UUCP> marcos@caus-dp.UUCP (Marcos R. Della) writes:
>
>I have spent some time pouring through this description and have not yet
>been able to produce anything that will work with it. My problem lies in
>the section that says T = (C ^ D) MOD K. The problem I face is that D is
>a large number and anything taken to a large number is rediculous in size.
>
But you are taking C^D MOD K.  Therefore the number will be no larger than
K.  If you are worried about size at intermediate calculations, how were
you planning on doing the powering?  You should do it by repeated squaring,
and at each step do the reduction modulo K.  That way all intermediate
calculations will be less than twice the number of bits in K.  (This is
not very unreasonable.....)

Does this clear things up?

-- 
Steve Tate			UUCP: ..!{ihnp4,decvax}!duke!srt
				CSNET: srt@duke
				ARPA:  srt@cs.duke.edu
"There ain't nothin' in the world that a T-Bone Shuffle won't cure."