Queries all ["auth_userdb"] plugins (multiple may be there) for the
given username and password, and returns (true) or (false) after
comparing against the database entries` password fields.

This function additionally sets $ewiki_auth_user if the password
matches, and also $ewiki_author if it wasn't yet.
prev << "ewiki_auth_user()"
next >> "Variables"

You cannot modify the ProtectedMode file, but anyhow any ideas or suggestion should as usually get filed on BugReports, UserSuggestions or even better the ProtectedMode.Discussion.