Semiconductor memory card, playback apparatus, recording apparatus, playback method, recording method, and computer-readable recording medium

A semiconductor memory card, comprising:

• a protected area;
• and
• an unprotected area,
• wherein the protected area stores an encryption key sequence composed of a plurality of encryption keys arranged into a predetermined order, and is accessible by a device connected to the semiconductor memory card only if mutual authentication between the device and the semiconductor memory card is successful,
• wherein the unprotected area stores a plurality of encrypted audio objects, a plurality of pieces of management information in one-to-one correspondence with the audio objects, and a playlist,
• wherein each audio object has unique identification information,
• wherein the plurality of audio objects includes:
• at least one audio object that only contains valid data that needs to be played back;
• and
• at least one audio object that contains (i) valid data and (ii) invalid data located at least one of before and after the valid data, the invalid data not needing to be played back,
• wherein the encryption keys are in one-to-one correspondence with the audio objects based on the unique identification information, and each used to decrypt a corresponding audio object,
• wherein each piece of management information includes attribute information, block information, and link information,
• wherein each piece of attribute information shows that a corresponding audio object constitutes (a) an entire audio track, (b) a first part of an audio track, (c) a middle part of an audio track, or (d) an end part of an audio track,
• wherein each piece of block information includes an offset from a start position of the valid data of a corresponding audio object and a length of the valid data that starts at a position indicated by the offset,
• wherein each piece of link information corresponding to an audio object constituting a first or middle part of an audio track shows an audio object constituting a middle or end part of the audio track that follows the first or middle part, and
• wherein the playlist shows a playback order of audio tracks and a playback order of audio objects in each audio track.