| 摘要 |
<p>A key control system comprises the generation of a first set of predetermined keys Kpred which are then used as master keys for a plurality of respective postage meters (12). The keys are then related to a respective meter (12) in accordance with a map or algorithm. The predetermined master key Kpred is encrypted with the date to yield a date dependent key Kdd related to the respective meter (12). The date dependent key is encrypted with a unique identifier or the respective meter to yield a unique key Kfinal that is by the respective meter to generate digital tokens. The Data Center (16) encrypts the date with each predetermined key Kpred to yield a table of dependent keys Kdd's. The table of Kdd's are distributed to verification sites. The verification site reads a meter's identification from a mailpiece being verified to obtain the dependent key Kdd of the meter (12). The verification side (34) encrypts the dependent key Kdd with the unique identifier to obtain the unique meter key which is used to verify tokens generated by the meter (12). In the preferred embodiment, the master key Kpred, the date dependent key Kdd, and the unique key Kfinal, in the meter are stored in the meter. In the alternate embodiment, the master key Kpred is encrypted with a unique meter identifier to obtain and the unique key Kfinal which is stored in the meter (12). The meter then generates its date dependent key Kdd, which is used to generate digital tokens. <IMAGE></p> |
