| 摘要 |
Methods that enable the providing of authorization for the use of an instrument comprising a computer for a period limited by a date or limited to a number of hours. The method consists in mingling the data elements of the program memory to be protected according to a secret order. To use this memory, a transcoding device is then used. This transcoding device makes it possible to restore the right order of reading the instructions contained in the memory. This transcoding device is preferably in the form of a memory that contains several tables, only one of which gives the right transcoding data elements. The choice between these tables is made under control that make it possible to determine rights of access to the instrument. These are preferably assembled together in the form of a smart carrier that gets inserted between the normal carrier of the program memory and this program memory itself. It can be used to check the rental period of instruments comprising computer systems and to obtain protection against the unauthorized use of the program memory.
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