[cap-talk] publishing a directory of subjects to ease capability introduction

[John Carlson]

I am thinking it would  be okay to publish a directory of subjects, as
long as the subject api only accepts new capabilities, and can't
receive other messages which might confuse the subject.  The
new capabilities would have to be understandable enough for
the user to decide whether they want to invoke the capability or
not, and it probably would be passive...the user would have to look
at a list of uninvoked capabilities to figure out whether they want
wanted to invoke the capability or not.  You could have a filter
which would screen out spam capabilities, and only show the
user the capabilities which  allow the subject to send messages
to whomever.  Thus I as Bob could introduce Alice to Carol by
sending my Bob's capability to talk to Alice to Carol.  Or if
Alice gave Bob the "introduction" capability, he could create
a new capability from it for Carol to talk to Alice (or vica versa)

What do people think about using this directory in a human
messaging system to initially distribute capabilities?  I think
this gets around "use another medium" to distribute capabilities.
It seems low risk, since the communication capabilities can
be revoked if they are misused.   The only thing that I can
see as a danger would be a massive denial of service attack,
where a ton of capabilities are sent to a particular user.  Does
someone have a good solution for that?  Can one revoke
privileges to the directory?

Once the initial set of capabilities have been distributed, then
more exciting things can happen.  I can see users sending
"send me chat from the group" to particular group subjects,
so they could join groups.  Once they are in groups, they
can meet other people, and get acquainted, without endangering
their security.  The group can restrict who is granted a capability
to send messages to it, through some kind of moderator control.

I'd love to implement this in my chat system, I have a family
now, and not so much time.

John