Information recording and reproducing apparatus and method

According to one embodiment of the invention, there is provided 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 includes a recording section which records in the recording medium an 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 on the basis of 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.