In <199807282235(_dot_)PAA26974(_at_)mail(_dot_)proper(_dot_)com>, on 07/28/98
at 05:36 PM, Paul Hoffman / IMC <phoffman(_at_)imc(_dot_)org> said:
At 11:49 PM 7/28/98 +0200, Ulf M?ller wrote:
Schnorr makes a plausible argument that DSA is covered by his patent
(see http://grouper.ieee.org/groups/1363/letters/SchnorrMar98.html),
and his European and Japanese patent claims are broader than the US
one. That probably means that there is no restriction to hardware
implementations in these patents.
RSA is the licensor of the Schnorr patents. When asked about this, they
have made no claims that these patents apply to DSA. If you read
Schnorr's letter carefully, he doesn't really either. He says "The above
mentioned patents apply to various implementations of ...". It appears
that he believes that you can implement DSA without infringing on his
patent, but various things you do can cause you to infringe. This is
similar to many other companies' "improvement patents".
Abstract:
We
compare the Digital Signature Algorithm (DSA) of NIST with EP-Patent
0384475. We show that DSA--signatures are step by step equivalent with an
instance described in and covered by the claims of EP-Patent 0384475.
Elliptic curve variants of the DSA are step by step equivalent with an
elliptic curve instance of EP-Patent 0384475.
And from the conclusion:
We have shown that DSA signatures are step by step equivalent to an
INSTANCE of the signatures presented and covered by the claims of
EP-Patent 0384475. The efficiencies of DSA compared to its precursor, the
ElGamal signatures, come from computing logarithms modulo q whereas in the
ElGamal signatures logarithms are modulo (p-1).
This novel feature of the PATENT has been presented for the first time in
public at Eurocrypt'89, April 10-13,1989 in Houthalen Belgium. The
presentation at Eurocrypt'89 made it clear that the novel efficiencies can
be used in connection with known discrete log signature schemes such as
ElGamal. The inventor of the DSA, David K. Kravitz, attended this
presentation.
I think it is quite clear that Prof Schnorr considers DSA to be covered by
his patent and there is the implication that the inventor of DSA based his
work directly off of Schnorr's.
Now as far as RSADSI "making no claims" is not very comforting. "Making no
claims" and publicly stating that they have no intentions now or in the
future to enforce Schnorr's patent against DSA implementations are two
different things. Preferably they would do so in a nice notarized document
from their legal department.
As things stand right now there is no reason for RSADSI to say anything.
Let everyone implement DSA in their standards and then send out the
lawyers to collect payments.
--
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