How do I block users from seeing links to reports that they are not authorized to view

I have a group of employees that all need to view different reports. I have some of the teams divided up so that their reports are collected in the same folders. The problem is that one folder may contain 100s of reports and any given user only has access to a few of them. How do I set up Reporting services to let each user only see the reports that they have access to?

i.e. If there are three folders (fld1, fld2, and fld3) and 100 reports in each; and John Dow only has access to rpt1 and rpt 2 in fld1 then when he logs on he should only see the fld1 folder from the home page and once he clicks on that link he will only see links to his two reports inside that folder.

I also have .Net at my disposal. So if I can't achieve this through RS how do I build a work around?