Encryption Key for Column-level Encryption

Hello All, We are potentially needing to implement column-level encryption for the first time, and I would appreciate some input from anyone currently using it. Can you give me an idea of how you are storing the password/encryption key? The manual states the below: "When you set a password, the database server transfers the password and any hint to a 128-bit key that is used to encrypt the password and hint. Passwords and hints are not stored as clear text. The key is a time-based random value per instance. The database server starts the key when the server starts; the key is deleted when the database server shuts down." Is this implying that you can only have one encryption password per instance, and that it is tied to the specific instance? Where does the engine get the password from on startup? Thanks for any input. Pam