Cross domain iframes and cookies

Question

Hello all,

I'm developing a web application using asp.net. In my application I require the user to plent an iframe which refers to an html document on my domain. I also give the user a script to put in his window which performs a call to my .ashx handler.

What I would like to do is as following:

1. The iframe in my domain needs to store a cookie.
2. When the main window performs a call to my handler (ashx)
3. the server needs to be able to access the cookie of the inner iframe (sitting in my domain).

Is this possible? If not, is there any workaround?