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Cryptographic communication system and method

  • US 20060204003A1
  • Filed: 02/28/2006
  • Published: 09/14/2006
  • Est. Priority Date: 02/28/2005
  • Status: Active Grant
First Claim
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1. A cryptographic communication system, comprising:

  • a plurality of communication terminals which perform cryptographic communication; and

    a management server which manages a communication condition of each of the plurality of communication terminals, wherein each of the communication terminals comprises;

    a plurality of encryption/decryption processing means for which different cryptographic algorithms are respectively used;

    common condition requesting means which transmits a common condition request to the management server, the common condition request containing a terminal ID corresponding to identification information of a self communication terminal and a terminal ID of another one of the communication terminals which corresponds to a communication destination terminal;

    common condition storing means which stores common condition information containing a terminal ID of a communication source terminal, the terminal ID of the communication destination terminal, an algorithm ID corresponding to identification information of the cryptographic algorithm that can be used by both the communication source terminal and the communication destination terminal, and plural pieces of key generation information;

    common condition obtaining means which receives the common condition information from the management server and stores the received common condition information in the common condition storing means; and

    cryptographic communication means which searches the common condition storing means for the common condition information having a terminal ID of a communication counterpart, selects, from the plurality of encryption/decryption processing means, the encryption/decryption processing means, for which the cryptographic algorithm having the algorithm ID contained in the common condition information found in the search is used, and uses the selected encryption/decryption processing means to perform the cryptographic communication with the communication terminal of the communication counterpart, wherein the management server comprises;

    communication condition storing means which stores, for each of the plurality of communication terminals, communication condition information containing the terminal ID of the communication terminal and the algorithm ID of each of the cryptographic algorithms respectively used for the plurality of encryption/decryption processing means provided for the communication terminal;

    common condition request receiving means which receives a common condition request from the communication terminal;

    common condition search means which searches the common condition storing means for the algorithm ID contained in both the communication condition information containing the terminal ID of the communication source terminal issuing the common condition request received by the common condition request receiving means and the common condition information containing the terminal ID of the communication destination terminal to which the common condition request is sent;

    key generation information generating means which generates plural pieces of key generation information, each containing a key used in the encryption/decryption processing means for which the cryptographic algorithm having the algorithm ID retrieved by the common condition search means is used or a key type for generating the key, and a key ID corresponding to identification information; and

    common condition transmission means which transmits the common condition information to each of the communication terminals, the common condition information containing;

    the terminal ID of the communication source terminal and the terminal ID of the communication destination terminal of the common condition request received by the common condition request receiving means;

    the algorithm ID retrieved by the common condition search means; and

    the plural pieces of key generation information generated by the key generation information generating means in response to the common condition request, the communication terminals each having the terminal ID of the communication source terminal issuing the common condition request and the communication terminal having the terminal ID of the communication destination terminal to which the common condition request is sent, and wherein the cryptographic communication means of the communication terminal sequentially selects the key generation information from the plural pieces of key generation information contained in the common condition information retrieved by the search, uses the key contained in the selected key generation information or the key generated from the key type contained in the key generation information to cause the selected encryption/decryption processing means to generate encrypted data, and transmits cryptographic communication information containing the encrypted data and the key ID contained in the selected key generation information to a communication counterpart, while selecting the key generation information having the key ID contained in the cryptographic communication information received from the communication counterpart from the plural pieces of key generation information contained in the common condition information retrieved by the search and using the key contained in the selected key generation information or the key generated from the key type contained in the key generation information to cause the selected encryption/decryption processing means to decrypt the encrypted data contained in the cryptographic communication information received from the communication counterpart.

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