Xref: utzoo comp.lang.pascal:483 sci.crypt:686
Path: utzoo!mnetor!uunet!husc6!rutgers!mcnc!ecsvax!wmcb
From: wmcb@ecsvax.UUCP (William C. Bauldry)
Newsgroups: comp.lang.pascal,sci.crypt
Subject: Re: Implimenting this system...
Message-ID: <4284@ecsvax.UUCP>
Date: 9 Dec 87 14:20:34 GMT
Reply-To: wmcb@ecsvax.UUCP (William C. Bauldry)
Organization: UNC Educational Computing Service
Lines: 28
Keywords: Public Key systems

In article <291@caus-dp.UUCP> marcos@caus-dp.UUCP (Marcos R. Della) writes:
>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.
>
>Does someone have a fix that will make this a better system or maybe
>another method that might not be as secure, but will still work on the
>same principle of the encrypt and decrypt keys?
>
>Any help would be appreciated...
>
>Marcos R. Della

Aside from the usual pointers to represent the power in terms of squares
and take mod k at each opportunity in intermediate calculations, the
main thought to keep in mind is the security of Public Key systems is
based on the *difficulty* of arithmetic (in particular factoring large
numbers) that comes up in en/de-crypting. i.e. it can't be too easy or
it's not secure. If your not really worried about security, then instead
of the system above (based on the RSA scheme) you could switch to a
Trapdoor type of coding where the arithmetic is much simpler - back in
1976/7 Scientific American had a very good article on both these systems.

Best of luck.

Bill Bauldry
Dept of Math Sci
Appalachian State U
Boone, NC