16. An apparatus as described in claim 15 wherein said enabling means further comprises memory means for storing preselected keys CD, said preselected keys CD having a one-to-one correspondence with said classes, and wherein said enabling means responds to said enabling information to enable access to a group of said preselected keys CD, said group of keys corresponding to said group of classes.
16. An apparatus as described in claim 15 wherein said enabling means further comprises memory means for storing preselected keys CD, said preselected keys CD having a one-to-one correspondence with said classes, and wherein said enabling means responds to said enabling information to enable access to a group of said preselected keys CD, said group of keys corresponding to said group of classes. 19. An apparatus as described in claim 16 further comprising: a) means for transmitting request information to a data center, said request information including encrypted information identifying said apparatus and a request for enabling information defining said group of said preselected keys CD corresponding to said group of classes, wherein said data center decrypts said encrypted identifying information and responds to send said requested enabling information to said apparatus.