| 摘要 |
Encryption synchronization (e-sync) is maintained between a transmitter ( 104 ) and one or more receivers ( 102 ) in a multi-modulation TDM system ( 100 ) where information is communicated in slots ( 402 ) comprising a slot header ( 404 ) and one or more data blocks ( 406 ), and wherein the data blocks are eligible to be encoded at different modulation rates thereby creating a likelihood of different numbers of blocks in different slots. The receiver and transmitter employ respective encryption elements ( 200, 300 ) comprising e-sync shifter elements ( 202, 302 ) and encryption algorithm blocks ( 204, 304 ). The e-sync shifter element provides an e-sync signal defining an encryption state vector to the encryption algorithm block and is operable to advance the encryption state vector (in the case of the receiver) according to a number of received bits plus a variable number of bits. The variable number depends on the number of bits within a block, the maximum number of blocks that could be within a slot and the actual number of blocks within the slot.
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