Everybody will tell you that it’s good practice to change your password periodically. It’s definitely true. Any computer user must do it. Here I’ll say a thing that must be done by paranoiac.

Take a stream of information that you create over year. Take note that the stream isn’t continuous but partitioned like a stream of email messages sent over time. If you encrypt the stream with a public-key encryption algorithm; you’ll be able to aggregate many message from different sources. The thing is that if you don’t change you public/private keys, anybody who discovers your private key will be able to access your entire stream over time if he logged it. This is a real problem if such a thing append. It’s why the concept of information partitioning is important. You only need to change you keys each n day and if your attacker find your current private key he’ll not have access to the whole stream of information. It’s a way to add security within the security provided by the cryptosystem.

As I said, it’s for paranoiac only. It’s just a little thought that come up in my mind today, enjoy it.