Device and method for controlling digital bidirectional communication

Abstract

An interface block ( 11 ) converts the format of input downstream data (STRM). A CPU ( 12 ) receives the format-converted data (DIF) and realizes the MAC function. A TEK process block ( 13 ) receives TEK process data (DTEK) obtained from the data (DIF), analyzes the data structure of the TEK process data, and performs decryption processing based on a result of the analysis.

1 . (canceled) 
   
   
       2 . A device for performing bidirectional control in digital bidirectional communication comprising:
 an interface block for converting a format of input downstream data to generate downward data;   a CPU which receives the downward data and realizes a MAC (Media Access Control) function; and   a TEK process block for receiving TEK (Traffic Encryption Key) process data obtained from the downward data, analyzing a data structure of the TEK process data, and performing decryption processing based on a result of the analysis,   wherein the TEK process block includes:
 a structure analysis block for analyzing an MPEG structure included in the received TEK process data and a MAC (Media Access Control) structure buried in the MPEG structure to perform error detection using HCS data and error detection using MAC header information except for HCS data and output MAC state information data that represents a state and meaning of MAC data having the MAC structure; 
 a decryption block for identifying encrypted part of the TEK process data by referring to the MAC state information data, decrypting the encrypted part using TEK data for cryptanalysis, and integrating a result of the decryption with unencrypted part of the TEK process data. 
   
   
   
       3 - 9 . (canceled) 
   
   
       10 . The device of  claim 2 , wherein the decryption block performs the steps of:
 referring to the MAC state information data to identify encrypted part and unencrypted part of the TEK process data;   extracting from the TEK process data TEK collation data for selecting TEK data;   referring to the extracted TEK collation data to select TEK data used for decryption from a plurality of items of pre-stored TEK data;   converting the encrypted part so as to have a bit width equal to a unit of decryption processing and decrypting the converted encrypted part using the selected TEK data; and   integrating the decrypted data and the unencrypted part.   
   
   
       11 . (canceled) 
   
   
       12 . A method for performing bidirectional control in digital bidirectional communication, comprising:
 the step of converting a format of downstream data to generate downward data;   the step of receiving the downward data to realize a MAC (Media Access Control) function by a CPU; and   a TEK process step of receiving TEK (Traffic Encryption Key) process data obtained from the downward data at a TEK process block to analyze a data structure of the TEK process data and performs decryption processing based on a result of the analysis wherein the TEK process step includes:
 a structure analysis step of analyzing an MPEG structure included in the TEK process data and a MAC (Media Access Control) structure buried in the MPEG structure to perform error detection using HCS data and error detection using MAC header information except for HCS data and generate MAC state information data which represents a state and meaning of MAC data having the MAC structure; and 
 a decryption step of referring to the MAC state information data to identify encrypted part of the TEK process data, decrypting the encrypted part using TEK data for cryptanalysis, and integrating a result of the decryption with unencrypted part of the TEK process data. 
   
   
   
       13 . (canceled)