Re: Diffie-Hellman

Unfortunately, Diffie-Hellman *is* patented, and I'm pretty sure Public Key Partners
(closely related to RSA) holds the patent, just as they hold RSA's.
To quote Steve Bellovin: 
	U.S. Patent Number: 4200770
	Title: Cryptographic Apparatus and Method
	Inventors: Hellman, Diffie, Merkle
	Assignee: Stanford University
	Filed: September 6, 1977
	Granted: April 29, 1980
	[Expires: April 28, 1997]
So we're stuck with it being patented until 1997.
Too bad - I was starting to think along the same lines about doing a D-H-based mailer.
It's non-trivial, if you have to worry about active eavesdroppers swapping
mail messages on you, and it's easier to do if there's a trusted Key Distribution
Center, and if you think about all the cases carefully you tend to re-create
either Needham-Schroeder or the Everhart-Osborn Bell Labs patent (~1980++),
but you can certainly do it for the common case that says the Bad Guys are
only listening to your mail and not tampering with it.

			Bill Stewart, wcs@anchor.ho.att.com

>I'm pretty sure Public Key Partners (closely related to RSA) holds
>the patent, just as they hold RSA's.

This is what I remember about PKP.  Public Key Partners is a
consortium of four, two industry and two academic members.  RSA Data
Security and Cylink are the industry partners.  I believe that
Stanford and MIT are the academic ones.

Eric

>From: wcs@anchor.ho.att.com (Bill Stewart)

>Unfortunately, Diffie-Hellman *is* patented, and I'm pretty sure
>Public Key Partners (closely related to RSA) holds the patent, just
>as they hold RSA's.

>Too bad - 

PGP violates PKPs patents. Everyone is using it. I'm not encouraging
patent violations -- I'm just noting fact.

Perry