Apparatus for limiting reproducible number of magnetic recording medium
US5796826A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 1, 1995 |
| Grant date | Aug 18, 1998 |
| Priority date | — |
| Expiry date | Dec 1, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2005/91364
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A reproducible number limiting apparatus for a magnetic recording medium using a reproducible number limiting algorithm is disclosed including: scrambling means for scrambling an input bit stream using a scrambling key; encryption means for encrypting the scrambling key used in the scrambling means' scrambling and additional information, and outputting a ciphertext; a key storage for storing an encryption key required in encryption; recording/reproducing means for recording or reproducing the output of the scrambling means and encryption means; decryption means for updating the additional information for every playback from the ciphertext using an encryption key, and destroying the scrambling key when the additional information satisfies a specific condition; and descrambling means for descrambling a reproduced bit stream using the scrambling key from the decryption means.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.