|  |  | There are three main areas in key aging. Per session aging creates and distributes a new key for every communication session. This procedure is very secure, but also very processor intensive. Per volume aging creates and distributes a new key after a certain amount of data is encrypted with one key. This is also a secure measure, but key generation can come at inopportune times. Gap keying generates and distributes a new key when there is a lull in transmission. This method uses processor time when it's not needed by another process, but in most networks there are few lulls in transmission.