A signal processing system includes a reproducing apparatus for reading information from a recording medium having unique information and an information processing apparatus for mutually authenticating and connecting the reproducing apparatus. The reproducing apparatus includes a final encryption key generating portion that generates a content information encryption key in accordance with intermediate key information. A first transmitting portion transmits the intermediate key information to the information processing apparatus. A second transmitting portion transmits the content information encryption key to the information processing apparatus. The information processing apparatus includes a content information encrypting portion that encrypts content information using the content information encryption key, and an intermediate key information encrypting portion that encrypts the intermediate key information using key information unique to the recording medium. A recording portion records the encrypted content information and the encrypted intermediate key information to the recording medium.