Recording apparatus, recording medium, playback apparatus, recording method and playback method
AssigneeSony Corporation
InventorsYoshizumi Inazawa, Tadashi Fukami, Keisuke Yamaoka
Life of this patent
Estimating the term…
Abstract
A recording method and a recording apparatus whereby digital data is recorded onto a disc as run-length limited code used for modulating marks or spaces on the disc and, at the same time, the recorded digital data is encrypted by using key data which is also recorded onto the same disc by varying the shape of marks or spaces with timing having no effect on the edges of the marks or the spaces. A playback method and a playback apparatus reproduces the digital data and the key data recorded on the disc by the recording method and/or the recording apparatus from the disc with the key data used for decrypting the reproduced digital data.
Claims6
A recording apparatus for recording digital main data as alternating marks and spaces on a disc by modulation of one of said marks and spaces in a run-length direction thereof in accordance with said data, said recording apparatus comprising:
- key-data generating means for generating key data;
- encryption means for encrypting said digital main data on the basis of said key data generated by said key-data generating means;
- key-data modulation means for modulating one of said marks and spaces in a width direction thereof in accordance with said key data generated by said key-data generating means;
- and
- recording means for recording said key data used in said modulating of one of said marks and spaces carried out by said key-data modulation means in a width direction thereof and for recording said digital main data encrypted by said encryption means,
- wherein said encryption means comprises a run-length detector for measuring a run length of one of said marks and spaces over a predetermined distance;
- random-data generating means for generating random data;
- and
- control means for varying the width of one of said marks and spaces in accordance with said random data generated by said random-data generating means and in dependence on a measurement output by said run-length detector.
A disc-shaped recording medium for storing digital information encrypted using predetermined key data on recording tracks by modulation of a series of alternating marks and spaces on each of said recording tracks, said disc-shape recording medium comprising:
- a program area having a plurality of said recording tracks wherein said encrypted digital information is recorded by modulating one of said marks and spaces in a length direction thereof;
- and
- a lead-in area wherein said key data is recorded by modulating said one of said marks and spaces in a width direction thereof,
- wherein said lead-in area is also used for recording said encryption-means-identification data used for selecting one of a plurality of encryption methods by modulating one of said marks and spaces in a width direction thereof, and
- wherein control data forms said key data and said encryption-means-identification data recorded in said lead-in area by modulating said one of said marks and spaces in a width direction thereof performs random-number processing.
Dependencies are inferred from the claim text.