| 摘要 |
<p>The method involves sending service attribute messages (SA) at 1-second intervals to a circuit (1) which inserts a check word (CW). Another circuit (2) introduces the number (3) of negative management messages (EMMN) sent since the last access control message (ECM). The current check word is stored (4) for insertion (5) into the EMMN to authenticate it w.r.t. the current service sequence. The next stage (6) increments the stored number of EMMNs and a circuit (7) calculates the compression of bytes in the message (EMM1) and one of four secret keys by a known hashing function. The other secret keys are applied to encryption circuits (8,9) and a compression calculation device (10) for the positive management message (EMMP).</p> |
