Patent ID: 8024583
Filing Date: 2011-09-20
Classification: H04L

Abstract:
1. A host device for processing confidential information, which reads an encrypted content from a target device storing encrypted confidential information that includes the encrypted content, and decrypts the encrypted content for use, the host device comprising: a confidential information processor performing operations according only to a plurality of predetermined sequences; a Central Processing Unit (CPU) which directs said confidential information processor to initiate the sequences; a first interface which inputs and outputs data including the confidential information between said confidential information processor and the target device; and a second interface which inputs and outputs data including the confidential information between said confidential information processor and said CPU, wherein: m+1 keys {K n keys {Kb the key Km is a content key for encrypting a content; the key Ki is encrypted with a key K (i−1), i being a natural number satisfying 1≦i≦m; the sequences include a key conversion sequence which converts a Ki encrypted with a K (i−1) into a Ki encrypted with a key different from the K (i−1), the to-be-converted encrypted Ki being a key of the encrypted m+1 keys; said host device further performs an authentication processing for the target device or the different target device; a key Kb the different key is a key of the keys {Kb said first interface and said second interface output the confidential information outside said confidential information processor, only when the confidential information is encrypted, after the key conversion sequence is initiated.