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The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:40 ADT
Bob Baldwin (baldwin@rsa.com)
Mon, 20 Jul 1998 11:04:36 -0700
The RC5 cipher is patented in the US and it
covers most forms of data and key dependent rotations.
It does not cover prior art such as the Madryga
cipher (see Bruce's book).
The RC6 cipher also uses data dependent rotates,
so it is covered by the RC5 patent, and it also contains
novel features that might become patented.
One of the ground rules for AES is that the winner
will not enforce patent rights against implementations of
AES that conform to the FIPS standards that will be
published for the winner. This does not mean that the
patent rights go away. For example, if RC6 becomes the
AES, then RC5 does not become unencumbered by patents.
Similarly, if the RC6 cipher is used in modes that are
not covered by the FIPS, then implementations of those
modes could be subject to patent enforcement. For example,
if the modes do not cover building a digest function out
of AES, then the winner will does not need to give up rights
to AES as the basis for a digest function.
These ground rules are basically the same ones that
were applied to IBM's DES submission, so if you are
comfortable (from a legal viewpoint, not a security
viewpoint) using DES, then you should be comfortable
(legally) using the AES winner.
--Bob Baldwin
Technical Director, RSA Data Security
> -----Original Message-----
> From: Perry E. Metzger [SMTP:perry@piermont.com]
> Sent: Monday, July 20, 1998 8:01 AM
> To: Julian Assange
> Cc: Kriston J. Rehberg; CodherPlunks@toad.com
> Subject: Re: CAST (and random AES chatter)
>
>
> Julian Assange writes:
> > Can someone tell me what the patent situation is with RC6, given that
> > RC5 is patented?
>
> Reputedly, it is covered by the same patents, but RSA DSI agreed to
> essentially give up the patents should RC6 be chosen as the AES.
>
> Perry
The following archive was created by hippie-mail 7.98617-22 on Fri Aug 21 1998 - 17:20:40 ADT