How broad are PKP's patents?

[solman@MIT.EDU]

Or more specifically, I'm interested in how broad PKP thinks they
are. I understand that they claim all public-key systems, but am
I correct that that claim is based entirely on the Diffie-Hellman
patent expiring in April, 1997?

Is Shamir's three-pass protocol as presented on page 376 in
applied cryptography covered?

If you you used his protocol with the RSA-like symetric algorithm
suggested, is it covered under the RSA patent? Would an elliptic
analog of this be secure?

Are there other cryptographically secure communtative symetric
ciphers that could be used in Shamir's three pass protocol?
Being able to use this without infringing on any patents would
effectively obviate the need for public key cryptography outside
of authentication.

What about probabilistic encryption using a BBS generator? Does
RSADSI claim that because it too depends on the computational
hardness of factoring?

Thanks in advance,

Jason W. Solinsky