Patent ID: 7706664

Claim:
A contents recording apparatus comprising: a recording unit which performs a record of a recording medium, in which the recording medium records a title key file registering therein at least one of a title key which encrypts each of plural title contents corresponding to a program video or sound, and title contents encrypted by the title key; a key file generating unit which generates at least one of the title key file and registers at least one of the title key in the generated title key file; a random number generating unit which generates a random number corresponding to each of the plural title key files; and a TKF random number generating unit which generates a TKF random number for encrypting other title key file associated with the title key file, wherein the recording unit records a set of the title key file generated and the random number in the recording medium, and the key file generating unit registers the random number corresponding to the title key file, the TKF random number corresponding to the title key file, and an encrypted title key, where the encrypted title key is formed by encrypting the title key with the random number registered in the title key file and with the TKF random number registered in the other title key file.