Rivest Patent

Jim Gillogly jim at acm.org
Fri Nov 13 16:20:45 PST 1998

Eric Cordian [mailto:emc at wire.insync.net] writes:
>> So we can't use the rotate instruction with a data-dependent shift 
>> count in a block encryption algorithm without a license from Ron?

"Harvey Rook (Exchange)" <hrook at exchange.microsoft.com> writes:
> It's a little bit more complicated than that. RC-6, which also uses data
> dependant rotations is patent free.

It's a little bit more complicated than that.  RC6 will be available
without licensing charges to anybody if it's tapped as the official
winner of the AES bakeoff.  If it's not selected, then it's my
understanding that RSADSI (Security Dynamics?) may choose to require
payment for licensing -- I assume based on the RC5 patent.  The current
understanding is that AES candidates sign over their rights only if they
are selected.  Several candidates have been explicitly put into the
public domain in advance of the selection process; RC6 is not one of these.

Please correct me if it's more complicated than <this>.
	Jim Gillogly
	Trewesday, 23 Blotmath S.R. 1998, 23:38, 11 Cimi 19 Zac, Third Lord of Night

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