Nice summary of prior work in the first part. I have a few niggles but
it's basically correct and well organized.
IPR Disclosure: Algorithm I described above for doing path authorization
after forwarding based on hostname from crypto signatures is patent
pending. License is expected to be compatible with GPL programs.
What's the application number? I don't see anything with your name in
the USPTO application database.
Also, where has this been implemented and how much mail have people
run through it? For a scheme this complex, it's important to have
data to compare the results of this scheme with simpler alternatives
like plain DK or S/MIME.
I went to your sourceforge page, and it looks like a placeholder, no
files at all yet.
R's,
John