Patent ID: 9270673
Filing Date: 2016-02-23
CPC Classification: G06F,H04L

Claim Text:
1. A key distribution system that distributes a key of content from a key distribution device to a terminal device, wherein the key distribution device comprises: a content holding unit configured to hold therein encrypted content that is content encrypted with use of a title key; a content signature holding unit configured to hold therein a content signature generated by an authorized signature device for verifying whether the encrypted content is authorized; a title key holding unit configured to hold therein the title key; a key generation unit configured to generate a converted title key by converting the title key with use of a parameter of the content signature, wherein a reconstructed title key can be subsequently generated as an authorized title key by reversely converting the converted title key with use of the parameter of said content signature; and a recording unit configured to record the encrypted content, the content signature, and the converted title key into a recording medium device, and the terminal device comprises: a receive unit configured to receive the encrypted content, the content signature, and the converted title key from the key distribution device; and a write unit configured to write the encrypted content and the content signature into the recording medium device, and to write the converted title key into a protected area of the recording medium device, wherein subsequently, said converted title key can be reversely converted to generate a reconstructed title key to decrypt said encrypted content and to play back the decrypted content.