David Kravitz, former member of the NSA, holds a patent on DSA [Kra93].
Claus P. Schnorr has asserted that his patent [Sch91] covers certain
implementations of DSA. RSA Data Security has also asserted coverage of
certain implementations of DSA by the Schnorr patent.
This is in line with what I posted before. RSA and Schnorr assert coverage
of "certain implementations of DSA". That is, there are implementations
that they don't claim coverage for. The previous message shows that Schnorr
now claims coverage over all DSA, although he has never made that claim to
the IETF, as far as I know, and did not claim so last fall when I contacted
him.
The TLS draft, which is still waiting to become an RFC, requires DSS but
has no patent claims for it, FWIW. However, that draft came out before the
publication of Schnorr's revised paper that now claims coverage of all DSA.
--Paul Hoffman, Director
--Internet Mail Consortium