This would give a motivated person a fair chance at getting a network and possibly a geographic fix on a person.

I'm not a cryptographer, but I think that is practically impossible

Four pieces of information are used to calculate hash : salt, sessionid, ip, nodeid

The salt doesn't have to be shared

A fifth piece of secret information could also be used

Only the hash and nodeid are publically accessible information

The salt and the 5th piece can be rotated either randomly or periodically (every other week) --- good luck using crypt breaker on a moving target

And for the biggest shocker :) the hash doesn't even have to be shared! There doesn't even have to be a hash

The whole scheme could , instead of a dynamically computed hash, simply use a randomly assigned number, or color

For the sake of argument, even if it were possible to break crypt and get an IP address -- so what?

Where is the motivation? Perlmonks isn't used for commerce or political or criminal publishing, so where is the attraction to try and reverse engineer an IP out of this hash?

? Some random nefarious perlmonk wants to prove that X post by Anonymous Monk was really posted by mr_mischief, because the IP is the same? in same block? same IPS? So he can say AHA , GOTCHA!?

:D

As BrowserUk says, Gods here can and do use their privilege to see through anonymity sham -- and goverments don't even need to be Gods

So, ip , no ip, I don't think it makes a difference :)

I didn't see a random salt per user in the example. There really shouldn't need to be a random salt. The point is anonymity, so leave anything that ties it to the user at all out. There's no need to prevent sensitive information leaking if there's no sensitive information. A crypt on the session ID and the root node ID should be plenty to assure separation of credit for the thread, so why include anything else in a publicly displayed string?

This all kind of assumes the idea would be picked up anyway, which is not by any means a foregone conclusion. It's all just painting a bike shed that may never be assembled.

The level of information trusted to the site admins shouldn't by default be trusted to everyone. Don't assume that giving up IP information to the public would be okay with everyone just because it's okay with you. Apparently you're forgetting (or simply not aware, but that's doubtful) of the issues of stalking and harassment other people have had to deal with.