Thanks for locating that line. I think between the two of us we've figured out all the relevant parts of the system and assessed what is going on with post ids

Thanks for locating that line. I think between the two of us we've figured out all the relevant parts of the system and assessed what is going on with post ids and ips in the database. At minimum, from my understanding, ipv4 addresses look 100% recoverable with the database and $hashSalt, and 3 upper octets recoverable as long as you have hashSalt, secure_trip_salt and an archive of the thread. Of course this is just from the board software perspective, so the next layer in assessing the privacy of the users with regards to what the FBI can get, is the server, hosting, and upstream providers whether intentional or otherwise may have additional identifying information , for example cache or logs that can be correlated with the posts.