Protection against the non-authorized inhibition of writing in certain storage areas of a smart card
US5434397A · kind A · utility
18Cited by
11References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jul 26, 1993 |
| Grant date | Jul 18, 1995 |
| Priority date | — |
| Expiry date | Jul 26, 2013 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07F7/0866
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
To counter illicit prevention of the invalidation of a smart card in a pay television network, for example when the period of validity for the card has expired, a verification of the card reader's ability to write to the card's memory is made. This verification consists in periodically sending a data item to be stored in the card. A counter on the card is reset by the writing voltage of the card's storage. In the event the writing voltage does not reach the counter, the counter's overflow output is connected to a read inhibition circuit which blocks functions of the card.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.