I was going to post this in General Chit-Chat, but figured this was more of an encrytpion/decryption question.

I've been curious about the info stored in cookies. For example, I know that Yahoo cookies stores your U/N and P/W info so that you don't have to login every time. If someone managed to get this cookie, they would be able to access that account unless the cookie expired. My question is, if the cookie does expire, is there still a way to extract that info using some type of decryption program or algorithm?