From bsy+@CS.CMU.EDU Sun Mar 29 03:06:22 1992
SUB: [bsy+@CS.CMU.EDU: Re: PD encryption programs for mail]
SUM: "Mark W. Eichin" <eichin@cygnus.com>->eichin


To: Cryptography-Digest@news-digests.mit.edu
From: bsy+@CS.CMU.EDU (Bennet Yee)
Subject: Re: PD encryption programs for mail
Date: 28 Mar 92 19:51:19 GMT
Reply-To: bsy+@cs.cmu.edu
SUB: Re: PD encryption programs for mail
SUM: bsy+@CS.CMU.EDU (Bennet Yee), bsy+@cs.cmu.edu->Cryptography-Digest@news-digests.mit.edu

In article <1992Mar27.233015.8182@robobar.co.uk>, gtoal@robobar.co.uk (Graham Toal "gtoal@vangogh.cs.berkeley.edu") writes:
>
>I've just been told that a new (European based) version of pgp (Pretty
>Good Privacy) is coming out soon; and if you can't wait, there's rpem.
>Try archie for both of them.  They're both RSA cyphers.

The ``r'' in ``rpem'' is for Michael Rabin, not Ron Rivest nor RSA.
While it is claimed that the Diffie-Hellman patent covers it (since it
claims to cover all public key cryptography) -- and some people will
go so far as to claim that the RSA patent covers it (since it does
involve modular exponentiation) -- the cryptosystems are different in
many important ways.  In particular, inverting the Rabin encryption
function is provably equivalent to factoring the modulus, whereas the
strength of RSA is not so well understood.  See the following
references for details.

-bsy

-- 
Bennet S. Yee           Phone: +1 412 268-7571          Email: bsy+@cs.cmu.edu
School of Computer Science, Carnegie Mellon, Pittsburgh, PA 15213-3890

==========
@TechReport(RabinFunc,
        Key="Rabin",
        Author="Michael Rabin",
        Institution="Laboratory for Computer Science,
                Massachusetts Institute of Technology",
        Title="Digitalized Signatures and Public-Key
                Functions as Intractable as Factorization",
        Year=1979,
        Month="January",
        Number="MIT/LCS/TR-212")

@Book(Chor,
        Key="Chor",
        Author="Ben-Zion Chor",
        Title="Two Issues in Public Key Cryptography:
                {RSA} Bit Security and a New Knapsack Type System",
        Publisher="MIT Press",
        Year=1986,
        Where="Cambridge, Massachusetts",
        Series="ACM Distiguished Dissertations")