| 摘要 |
A method and apparatus for synchronizing cipher encoding is disclosed. A first transceiver transmits a signal to second transceiver, wherein the signal contains information (either clear or enciphered) and a unique word (e.g., UWA or UWB). The unique word and the current deciphering state are used by a cipher synchronizer to determine the next deciphering state, the next enciphering state, and the next encoding state. The cipher synchronizer makes this determination by following four rules. The first rule declares that if the current decode state is UWA and the current decipher state is "clear", then the next decipher state will be "clear", the next encipher state will be "clear", and the next encode state will be UWA. The second rule declares that if the current decode state is UWB and the current decipher state is "clear", then the next decipher state should be "decipher", the next encipher state should be "encipher", and the next encode state should be UWB. The third rule declares that if the current decode state is UWA and the current decipher state is "decipher", then the next decipher state should remain "decipher", the next encipher state should remain "encipher", and the next encode state should be UWA. The fourth rule declares that if the current decode state is UWB and the current decipher state is "decipher", then the next decipher state should be "clear", the next encipher state should be "clear", and the next encode state should be UWB.
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