| 摘要 |
<p>An external storage medium which can be connected to a computer and onto which user data can be written by a user of said computer, that medium comprising:
a storage unit for storing therein said user data;
a storage unit for storing therein an expiration condition;
a counter and/or a timer for incrementally measuring a time value and/or a number of events;
a connectivity detection unit for detecting whether said external storage unit is connected to said computer or not;
a control module for if said connectivity detection unit detects that said external storage medium has been detached from said computer, triggering said counter or said timer to start to operate, said control module being adapted to compare the value of said measured time and/or said measured number of events with said expiration condition, whereas if said control unit determines that said value of said measured time and/or said measured number of events coincides with said expiration condition said control unit carries out a processing such that said user data cannot be freely accessed any longer by a user of a computer to which said external storage medium is connected.</p> |
