ASP.NET Request.ClientCertificate returning empty on IIS 7

Basically it boils down to the fact that the client can't provide the client certificate. That's why you get the 403.7 error when you require it. I believe you need this:

http://blogs.msdn.com/b/puneetgupta/archive/2009/08/03/where-is-the-client-certificates-ui-in-iis-7-0.aspx

Please let me know if this helps.

I came across this question while looking for more information about how to get certificates in IIS 7 vs. IIS 6. I see that @whosrdaddy's solution worked for the asker. There is something else that I had to hunt down.

One of the differences between IIS 6 and IIS 7 is that IIS 6 has the "Directory Security" tab in each web site's configuration. In order to make the web server request certificates in IIS 7, you must click on the "SSL Settings" feature for the Web Site or Virtual Directory you are configuration to see the "Client certificates:" setting: Ignore, Accept, or Require.

Make sure that this is not set to "Ignore", or else you will never get your certificates to work!