Digitally sign using client certificate in ASP.Net

I am trying to digitally sign information with a private key. I know how to do this on in a desktop client application with .Net, but am not sure how to do it in ASP.Net. It would be used on an intranet using IE8. If it is done via ASP.Net, I am guessing that the private key is not sent to the server when the user types in their certificate passowrd when going to the site (https, 2-way SSL), but am not sure. If there is no way to access the client private key on the server, then how can I sign something in the browser? Can I use javascript?

Strange behavior using HTML ‘readonly=”readonly”‘ vs. JavaScript ‘element.readOnly = true;’

Some background So I was finishing up some enhancements in a web application that does some automatic interpolation of data. There are a handful of textboxes that the user fills out, and other textboxes in between them have values automatically calculated. The textboxes that receive automatically calculated values must be readOnly to prevent user changes, … Read more