Thread View: sci.crypt
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Started by Robert Cain
Thu, 01 Oct 1992 19:21
RSA claims 33 and 37 of U.S. patent 4,405,829
Author: Robert Cain
Date: Thu, 01 Oct 1992 19:21
Date: Thu, 01 Oct 1992 19:21
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The patent contains as claim 33:
In a communication system an encoding means for transforming a
transmit message word signal M to a ciphertext word signal C
where M corresponds to a number representative of a message and
0 <= M <= n-1
where n is a composite number and where C corresponds to a number
representative of an enciphered form of said message and corresponds
to
C = a[e]*M^e + a[e-1]*M^(e-1) + ... a[0](mod n)
where e and a[e], a[e-1], ... a[0] are numbers.
Claim 37 is nearly identical except that cryptographic use is specifically
claimed.
Thus it appears that any cryptographic method using a polynomial modulo
a composite infringes. I am seeking opinions, particularly from any
legal experts that may read this as to whether this claim which essentially
claims the use of a single mathematical formula is defensable?
Further I would like to know if anyone is aware of any prior art (filing
was Dec. 14, 1977) using a polynomial as simple as C = M^2(mod n) even that
would invalidate this claim.
Thanks,
Bob
--
Bob Cain rcain@netcom.com 408-358-2007
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Re: RSA claims 33 and 37 of U.S. patent 4,405,829
Author: Jon Luckey
Date: Fri, 02 Oct 1992 16:36
Date: Fri, 02 Oct 1992 16:36
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rcain@netcom.com (Robert Cain) writes: >Further I would like to know if anyone is aware of any prior art (filing >was Dec. 14, 1977) using a polynomial as simple as C = M^2(mod n) even that >would invalidate this claim. In volume 2 of _The Art of Computer Programming_ (Semi-numerical Algorithms), Knuth mentions a "interesting alternative to the RSA scheme" based on C=M^2(mod x), which he calls a SQRT box. It was developed by Micheal Rabin, and is described in [MIT Lab. for Comp. Sc., report TR-212 (1979)]. I'd start by looking there, even though the report is dated 1979, the concept may go back before 1977.
Re: RSA claims 33 and 37 of U.S. patent 4,405,829
Author: Robert Cain
Date: Tue, 06 Oct 1992 21:09
Date: Tue, 06 Oct 1992 21:09
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It has been pointed out to me that Julius Ceasar used the polynomial
C = M+1(mod n)
where M are the alphabet message chunks and n is the size of the
alphabet. For english n=26 which is the composite of the two primes
2 and 13 so I believe that prior art (very prior) has been established.
Any comments?
Bob
--
Bob Cain rcain@netcom.com 408-358-2007
____________________________________________
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\ Flames to /dev/null Advice by email! /
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-----------------------------------
Re: RSA claims 33 and 37 of U.S. patent 4,405,829
Author: Casper H.S. Dik
Date: Tue, 06 Oct 1992 23:18
Date: Tue, 06 Oct 1992 23:18
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rcain@netcom.com (Robert Cain) writes: >It has been pointed out to me that Julius Ceasar used the polynomial > C = M+1(mod n) >where M are the alphabet message chunks and n is the size of the >alphabet. For english n=26 which is the composite of the two primes >2 and 13 so I believe that prior art (very prior) has been established. >Any comments? You cannot take a patent apart claim by claim. The patent is the combination of the claims, not a mere collection. If I combine several well known things for the first time and the things have never been used in that combination before, I can patent it. Casper
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