The terminal device 600 comprises: a read unit configured to read encrypted content and a content signature from a regular region of a recording medium device 700, and to read a converted title key from an authorized region of the recording medium device 700, the converted title key having been converted from a title key with use of a content signature generated by an authorized signature device 500; a title key reconstruction unit configured to generate a reconstructed title key by reversely converting the converted title key with use of the content signature read by the read unit; and a playback unit configured to decrypt the encrypted content with use of the reconstructed title key to obtain decrypted content, and to play back the decrypted content.