I was reading Practical Unix and Internet Security, when I came across the following lines which I couldn't comprehend.
If you are using the wu archive server, you can configure it in such a way that uploaded files are uploaded in mode 004, so they cannot be downloaded by another client. This provides better protection than simply making the directory unreadable, as it prevents people from uploading files and then telling their friends the exact filename to download.
A permission of 004 corresponds to
-------r--. Can't a file be downloaded if it has read access? Also why is it considered better than simply making the directory non-readable? What does this imply?
Note: This is with regard to unauthorised users leaving illegal and copyrighted material on servers using anonymous FTP. The above solution was suggested to prevent this along with a script which deletes the directory contents after a period of time.