Due to a bug in Flash, I have to use the ASPXAuth cookie to log a user in on a page that a flash upload script calls after upload. See this page for more information: http://geekswithblogs.net/apopovsky/archive/2009/05/06/working-around-flash-cookie-bug-in-asp.net-mvc.aspx
I have to make the ASPXAUTH string "public" in the sense that it will be in the HTML of the page. My question is, how secure is this?
I understand that anyone that can get to the string in the HTML can probably get to it from the cookie just as easily, but let's say someone does have this ASPXAUTH string. Is it possible that they can login as another user using this cookie? Would they be able to decrypt it?
The value of the Forms Authentication cookie could be decrypted if a 3rd party had obtained the decryption key used by your website. Otherwise, I guess it would be a case of using brute force methods to crack it.
Make sure you prevent the page from caching at both client , proxy and server.
You really don't want the page to be stored in any caches if it contains aspxauth cookie values in the markup.
Personally I would use SSL for the connection if it was very sensitive data.