Information distribution system wherein storage medium storing ciphered information is distributed
US5440631A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 26, 1993 |
| Grant date | Aug 8, 1995 |
| Priority date | — |
| Expiry date | Apr 26, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B20/0021
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A system for use when distributing information stored in a piece of storage medium from a supplier to users through a distributor(s). The information is ciphered when stored in each piece of storage medium in a supplier apparatus. In addition, ciphered key information may be stored in the piece of storage medium together with the above information to be distributed. A distributor apparatus may convert the cipher of the key information before distributing the piece of storage medium to the users. The distributor apparatus may write further information in the piece of storage medium before distributing the piece of storage medium to the users. The further information indicates a limit of an operation of reading the information by each user, and may be a maximum allowable accumulated time of reading the information by each user, a maximum number of repetitions of the reading operation of the information by each user, or a time limit of the operation of the reading operation by each user. Each user apparatus stops the reading operation when the reading operation has reached the limit. Further, each user apparatus may write information indicating an amount of the reading operation there…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.