| 摘要 |
<p>A cavity (11), in which is established a high-frequency electromagnetic field, is arranged, on the insertion path of the portable object into the reader, upstream from the pickoff device (3) provided on the reader for picking off the electrical signals on the electronic circuit (21) of the portable object. If a conducting connection (25), provided by a fraudster in order to deceive the reader with the aid of a portable computer, for example, crosses this cavity (11), it behaves like an antenna, which senses a signal at the frequency of the electromagnetic field. The signal sensed is found amoung the signals picked off and its detection controls inhibition of the reader. The invention applies especially to readers for portable objects known by the name of "chip cards". <IMAGE></p> |
