| 摘要 |
PURPOSE:To select the presence/absence of ciphering and a ciphering system in matching with the chipering function of an opposite party by realizing a ciphering/decoding function and a transmission control function incorporatedly so as to reduce the memory access for the ciphering/decoding. CONSTITUTION:The information required for a protocol control section 1 accesses a memory section 2 via a DMA control section 3. The information is transmitted/received between the DMA control section 3 and the control section 1 via a signal path 31. Then the data of layer (n) subjected to protocol processing having a layer (n) or below and sent to the line 11 at the control section 1 is read by the DMA control section 3 and the memory section 2, then subjected to ciphering processing by a ciphering section 4 and the result is given to the control section 1. Conversely, the reception data from the line 11 is subjected to the protocol processing by the control section 1, decoded by the ciphering section 4 and written in the memory section 2. It is possible to transmit/receive the data to the line 11 without ciphering and to use the signal line 31 without through the ciphering section 4, and the control section 1 decides the use/diuse of the ciphering section in matching with the function of the opposite side at the connection with the opposite party. Moreover, the control section 1 controls the ciphering system of the ciphering section 4 in matching with the ciphering function of the opposite party at the call setting of the layer (n).
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