NODE da29d75aRe: Question on Diffie-Hellman patent
Tim Dierks <timd@consensus.com>Mon, 20 Jan 1997 11:13:00 -0800 (PST)
At 11:24 AM -0500 1/20/97, Amanda Walker wrote:
>Please excuse if this is a FAQ.
>
>I'd been operating under the assumption that the Diffie-Hellman patent
>(4200770) will expire on April 29, 1997 (17 years after the date of issue).
>Several people have recently told me it doesn't expire until September,
>evidently confusing the date of issue with the filing date. However,
>does anyone know of another patent (Hellman-Merkle, perhaps?) that would hve
>an impact on software that does D-H key exchange? We've got some planned
>uses
>of DH; while it doesn't seem cost effective to pay to license DH at this
>point, that six-month difference is something I need to plan around if
>necessary.
As a result of the GATT treaty, patent expiration times for some US patents
changed. The international standard is 20 years from filing, while old US
law was 17 years from issue. On the day which GATT took force for the US
(June 8, 1995), all outstanding patents' expiration dates were changed to
20 years from filing or 17 years from issue, whichever is later. This
affects some cryptography patents as follows:
Here's a summary of some relevant crypto patents:
Name Number Filed Issued Expires
Diffie-Hellman 4,200,770 Sept. 6, 1977 Apr. 29, 1980 Sept. 6, 1997
Hellman-Merkle 4,218,582 Oct. 6, 1977 Aug. 19, 1980 Oct. 6, 1997
RSA 4,405,829 Dec. 14, 1977 Sept. 20, 1983 Sept. 20, 2000
Data from <http://patents.cnidr.org/patbib_index.html>
References:
<http://www.lightlink.com/bbm/gatt.html>
<http://www.cushman.com/articles/artpat10.htm>
- Tim
Tim Dierks - timd@consensus.com - www.consensus.com
Software Haruspex - Consensus Development
Developer of SSL Plus: SSL 3.0 Integration Suite
NODE cebc0f08Re: Question on Diffie-Hellman patent
Andrew Loewenstern <andrew_loewenstern@il.us.swissbank.com>Mon, 20 Jan 1997 13:36:00 -0800 (PST)
Tim Dierks writes:
> Here's a summary of some relevant crypto patents:
>
> Name Number Filed Issued Expires
>
> Diffie-Hellman 4,200,770 Sept. 6, 1977 Apr. 29, 1980 Sept. 6, 1997
> Hellman-Merkle 4,218,582 Oct. 6, 1977 Aug. 19, 1980 Oct. 6, 1997
> RSA 4,405,829 Dec. 14, 1977 Sept. 20, 1983 Sept. 20, 2000
So who's planning on throwing a big party on Sept. 6th? Will Jim Bizos be
celebrating? :-)
andrew
NODE 40aecdfdRe: Question on Diffie-Hellman patent
Sandy Sandfort <sandfort@crl.com>Mon, 20 Jan 1997 13:56:56 -0800 (PST)
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SANDY SANDFORT
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C'punks,
On Mon, 20 Jan 1997, Andrew Loewenstern wrote:
> Tim Dierks writes:
> > Here's a summary of some relevant crypto patents:
> >
> > Name Number Filed Issued Expires
> >
> > Diffie-Hellman 4,200,770 Sept. 6, 1977 Apr. 29, 1980 Sept. 6, 1997
> > Hellman-Merkle 4,218,582 Oct. 6, 1977 Aug. 19, 1980 Oct. 6, 1997
> > RSA 4,405,829 Dec. 14, 1977 Sept. 20, 1983 Sept. 20, 2000
>
> So who's planning on throwing a big party on Sept. 6th? Will Jim Bizos be
> celebrating? :-)
I'll call dibs on that.
S a n d y
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