It is possible to use api.php on a wiki to which one does not have
access (read-only or otherwise) to do some things to which access
through the interface is denied.
For example, I can obtain a list of all pages on
board.wikimedia.org or
internal.wikimedia.org (neither of which I have read or write access
to), while attempting to view Special:Allpages on one of these gives a
"login required" error.
Attempting to retrieve revision information via the API correctly gives
a "no read permission" error, so I can't actually see the content of any
pages.
Is this a bug, or a feature?
-Gurch