I like the idea of sending the timestamp twice, with one being hashed. The only direct problem with that would be NoNonsense Forum being completely OpenSource, the hashing algorithm would be available. It means a hidden SALT will have to be used, which in Kroc’s case means he has to work on 2 different versions of the forum code: one for use here with a secret SALT and one for sharing with a public SALT. The latter might then be used wrong by others which makes them vulnerable to spam bots using the public SALT.

As for a way coders could protect their timestamp I find it absolutely brilliant! Much better a solution than my obscuring the data.

Of course the forum should never check the timestamp for being too old, unless this is set to an hour. Some threads might take long to read and some replies even longer to write.