| 摘要 |
The device comprises a key including a passive memory area 108, 109 and a shift register 102, the code contained in the passive area being intended to be transferred into the shift register 102 when the key is inserted into a lock, so that the said code may be transferred from the shift register into the lock in order to be compared there with a reference code contained in the lock. The key comprises a circuit 123 provided with a counter 124, 125 which is incremented each time voltage is applied to the key and with a system 126, 127, 128 for setting the counter 124, 125 back to zero when the code is successfully transferred out of the key, in such a way that after a number, determined by the counter, of unsuccessful transfer attempts, the passive memory area 108, 109 is destroyed by the output signal sent out by the counter 124, 125. <IMAGE>
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