Write cookies from subdomain and read from another subdomain without changing web.config

Question

I have a simple question. I have two different projects like

http://login.mydomain.com

and

http://test.mydomain.com

. As it's name suggests, I login from login project and response redirect to test project.

I am able to create cookie for login.mydomain.com but I can not read it from test.mydoamin.com.
My question is can I create cookie from login.mydomain.com to www.mydomain.com and read it from test.mydomain.com as if I am reading it from www.mydomain.com.

This is how I create my cookies.

Response.Cookies["UserValidForMyDomain"].Value = myvalue;
Response.Cookies["UserValidForMyDomain"].Expires = dtExpireDate;

and how I read them.

string myValue = Request.Cookies["UserValidForMyDomain"].Value;

Answer 1

No, but you can create a wildcard cookie for the domain of .mydomain.com which will allow any subdomain to read/write it.

Answer 2

TO WRITE

HttpCookie hc = new HttpCookie("key", "value");
hc.Domain = ".mydomain.com";
hc.Expires = DateTime.Now.AddMonths(3);
HttpContext.Current.Response.Cookies.Add(hc);

TO READ

HttpContext.Current.Request.Cookies["key"].Value

Answer 3

In php this will do session_set_cookie_params

In asp and equivalent, these stackoverflow thread might be usefull

How to share session among Multiple Domains on single asp.net website?

How can you keep a session across multiple subdomains in c# mvc?