Patent ID: 7619953

Claim:
A recording and playback apparatus for recording data on a recording medium that allows additional writing, the recording and playback apparatus comprising: recording means for recording first data on the recording medium; random-number generating means for generating a random number; and calculating means for calculating a first apparatus identification code, the apparatus identification code indicating that the first data has been recorded on the recording medium particularly by the recording and playback apparatus, by applying a predetermined function to data included in the first data recorded on the recording medium by the recording means, the data including second data that changes on each recording on the recording medium by the recording means and including the random value generated by the random-value generating means; wherein the recording means further records the random value generated by the random-number generating means and the first apparatus identification code calculated by the calculating means on the recording medium so that the random value and the first apparatus identification code are included in the first data.