Patent ID: 7926115

Claim:
An information recording and reproducing apparatus which records information in a recording medium and reproduces information recorded in the recording medium, the information recording and reproducing apparatus comprising: a recording section which records in the recording medium a first encrypted encryption key aggregate where at least one encryption key for encrypting each of a plurality of pieces of information has been encrypted and registered and information encrypted using the encryption key; a necessity determining section which determines, based on conditions decided according to the type of the recording medium, whether to record the first encrypted encryption key aggregate into the recording medium; wherein the recording section records in the recording medium the first encrypted encryption key aggregate determined to have to be recorded; and wherein when the type of the recording medium is rewritable media, the necessity determining section determines that the first encrypted encryption key aggregate has to be recorded into the recording medium only if at least one of the following conditions is satisfied: (1) the operation of recording the encrypted information into the recording medium or the operation of deleting the encrypted information from the recording medium has been carried out; (2) a second encrypted encryption key aggregate generated by encrypting a media key using a plurality of device keys has been updated; and/or (3) none of the number of updates of the first encrypted encryption key aggregate and those of said plurality of duplicates recorded in the recording medium are the same.