| 摘要 |
<p>The ticket includes a magnetic track on which a first message (3) is permanently recorded - for example by varying the thickness of the track. This first message comprises a random number expressed in binary form. A message (4) corresp. to the service to which the card user is entitled is magnetically recorded on the same track as the first message, and superimposed on it. A third message (5) corresp. to the first is magnetically recorded farther along the track. The message (4) may for example indicate the period of validity of the ticket, while the two messages (3, 5) are checked together in order to check the authenticity of the card. The two messages (4, 5) which are magnetically recorded are applied to the card at the time of issue, after the permanent message has been read.</p> |
