Tenders Web site which contains information about the projects for construction industry. The registered users divided by different trades: architects, builders, plumbers etc. For different trades may be different files (drawings, photos) to be downloaded, so I need to allow for the Builders to download only necessary files and restrict the other trades to download the Builders files. I will put the links for those files at the aspx page, if the user logged as Builder (Plumber, …), so they will download them.
But if the address of a file will be known to somebody, he can download it as well.
Question: how can I permit only for the designated person to download the files?
Thanks for any suggestions.