Protection against the non-authorized inhibition of writing in certain storage areas of a smart card
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United States of America Patent
Stats
-
Jul 18, 1995
Issued Date -
N/A
app pub date -
Jul 26, 1993
filing date -
Nov 3, 1989
priority date (Note) -
Expired
status (Latency Note)
Importance
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.
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