| 摘要 |
A technique for updating a master key while maintaining interoperability is provided. An encrypted data memory stores an encrypted master key obtained by encrypting a master key using a device key stored in a device key memory. A master key decoder produces a master key by decoding the encrypted master key stored in the encrypted data memory using the device key stored in the device key memory. From the above-described master key, a master key of an older generation can be produced. More specifically, a master key of an older generation can be produced by applying a predetermined unidirectional function to the former master key. <IMAGE> |
