Patent ID: 7319752
Filing Date: 2008-01-15
Classification: G11B,H04N

Abstract:
1. An information playback device for playing back information recorded on a recording medium, said information playback device comprising: cryptosystem means for executing decryption processing on data read from said recording medium; and secret-information decoding means for reading secret information stored on said recording medium by executing a data-reading process, which is different from a process of reading content data stored on said recording medium, for generating one or more M-series signals and decoding the secret information using the M-series signals; wherein said cryptosystem means generates a content-decryption key by using a hash function and, as a key-generating data, the secret information which is decoded after being read from said recording medium in accordance with either an analyzing data-recording key mode or a non-analyzing data-recording key mode, and executes, based on the generated content-decryption key, the decryption processing on the read data; and wherein said cryptosystem means uses the read secret information to generate the content-decryption key, and the read secret information is allowed to be used only in the generation of the content-decryption key which is executed in said cryptosystem means, without being stored in a storage means which is readable from the outside of said information playback device.