Anon IRC (Anonymous vs. Private)

[Panzer Boy]

I have been running an Anonymous IRC server for a short time now.  This
allows a real time conversation, as opposed to the monologue provided via
netnews or mail.

Currently, when a user logs in, the internal (and external) representation
of the user is:

NICKNAME!user at anon.host

Users have the ability to change their Nickname, and all other people have
to identify people is by their Nickname.  People who have used IRC for
awhile have told me that this would promote anarchy on the channels,
because it makes it impossible to ban/ignore certain people from
conversations.

So my fix is going to be running users Hostname through a one-way hash
function.  So references to users will be:

NICKNAME!user at HASH(Real-Hostname)

The question is, what kind of hash do it use?

My first idea was to use a hash function that has many collisions, a
simple "summing" of the ascii characters.  This would make sure that
people would have certain ID's, and ban/ignore would work.  This would
also make it harder to be sure you had the correct host if you were going
to try to brute force out a users hostname.

A couple other people have suggested using a hash function that is much
more complex.  So that no collisions will occur, and all users will have
unique "ID's" associated with their Nickname.

If collisions occur, it is ok.  Just the possibility for banning/ignoring
people you don't intend goes up.  Any suggestions on this one?

I was also thinking of allowing users to come on the system as
NICK!user at anon.host and then switch between that, and their
NICK!user at HASH(Real-Host).  This would allow people to be both completely
anonymous or, if they wanted, have and identity attached to themselves. 
This way people could ban/ignore anyone at "anon.host" if they didn't want
to deal with "anonymous" people.

To connect to my server, load up an IRC client, and change your server to
"drown.slip.andrew.cmu.edu".
In standard clients, "/server drown.slip.andrew.cmu.edu", is how to do this.

For more information about irc, ftp to CSA.BU.EDU.

-Matt
panzer at drown.slip.andrew.cmu.edu