Perfect Secrecy approaches the idea of "perfect encryption". It basically states that if the cipher text, encryption key, and the plain text are changing at a consistent rate -- you are approaching perfect secrecy. The theory states that if someone intercepts a cryptogram or some cipher text, that person could not deduce anything about the original plain text by studying the cipher text or its patterns. There is no pattern one could extrapolate from the cryptogram over time and the likelihood of someone guessing the plain text message is the same whether they observed and recorded the cryptogram or not. This means that any encrypted message that an attacker sees is completely meaningless and cannot be used to reconstruct the plain text or "the a priori probability of a plain text message M is the same as the a posteriori probability of a plain text message M given the corresponding cipher text." Brute force attacks simply do not reveal anything because the key is constantly changing. One Time Pad is a theoretetically unbreakable symmetric encryption cipher that share Shandy's "perfect secrecy" property.
I went over to my folks for Thanksgiving this afternoon and then later this evening to the in-laws. It was nice spending time with the family and taking a day to be thankful for all the things we take for granted. Happy Thanksgiving 2005 everyone !