I just want to know whether its possible to upload a file using joomla that wouldnt be downloable at all, I tried saving the file as a read only pdf file but that still made the file downloable on the web.
Taking into consideration that the internet is hard to contriol I just want to explore all possble suggestion prior to me concluding that it would be impossible.
in PHP you could move the uploaded file to a directory outsite public_html, so that is not directly accessible by a remote client, the file then can be served only through a script. If you cannot move it out, then you can use .htaccess rules to limit the access to the defined directory.
However I don't know if Joomla allows such setups. I see they suggest how to block access to some specific files:
If it is viewable or clients know exactly what the URL is, it is possible to download the file unless your server has permission set up to access the file. If you are talking about viewing it as PDF but not allow downloading, you may need something similar to Google Book. However, there is still a work around to download the content, just a bit harder to figure out...