On 7/18/14, Ricordisamoa ricordisamoa@openmailbox.org wrote:
The CC BY-SA license, used on most WMF projects, requires /attribution/. Attribution for edits made by unregistered/unlogged users is done by the exclusive means of their IP address. By clicking the 'Save' button, they agreed to release their edits under CC BY-SA, and that their IP address would have been the only form of attribution of their changes to them. While we can assume that there aren't any collisions between hashes of IP addresses, and we could change the attribution requirements for new edits, hiding or modifying the way IP addresses /of unregistered users who edited before that change/ are shown would be a substantial CC BY-SA infringement, as would be a change of registered users' names without their consent and without public logs of that change.
Additionally, if we used the same hash function as for new edits, it would make it pretty trivial to figure out what most of the hashes are. I think its safe to say we wouldn't modify old edits. After all, you can still look at https://en.wikipedia.org/wiki/Special:Contributions/216.143.215.xxx despite us not using that scheme anymore.
--bawolff