there are a lot of different ways to encrypt cookies. it all depends on the technology being used by the server that placed the cookie on your hard drive. It could be simple password encryption using your IP address as the key up to a high level of encryption. you would have to know what application the server used first to narrow down the type of encryption it is using.
Some cookies aren’t encrypted at all. Cookies– and the data they contain are controlled by the person or entity that created them on your hard drive. They really could contain <b>any </b>information you provide to the web site and be unencrypted, loosely encrypted, or tightly encrypted.