Hi,
Unfortunately it doesn't work . I had restricted the content type AND the field AND the directory in which the files are stored, this directory is in the disallow list of the robots.txt.
The problem is the URL that is generated by Seblod to download the file somehow "leaked" to google but that's not the worst part. The URL is accessible by just about everyone because it's not the direct path to the file in the directory (password protected via .htaccess) but a link following this pattern:
http://www.domain.com/component/cck/?task=download&file=field_name_for_file_upload &id=xxxxx
Seblod should not allow users to follow this link when they are not logged in with the necessary access rights, but it does.
All the access restriction on the list field does is not display the link but if anyone can "guess" the link they can see the content. It's a serious securyti issue.
Regards.
Xav