US 2007/0192583 A1Published application

Communication support server, communication support method, and communication support system

AssigneeHitachi, Ltd.

InventorsOsamu Takata, Takahiro Fujishiro, Tadashi Kaji, Kazuyoshi Hoshino

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Abstract

When a cryptographic communicating part 208 of the communication support server 20 exchanges information with the information processing units 14, if the term of validity of a first key stored in a cryptographic key storing part 200 and corresponding to the identification information of the information processing unit 14 does not expire, the cryptographic communicating part 208 performs the cryptographic communication with the information processing unit 14 using the first key, without performing a process of authenticating the information processing units 14. When the term of validity of the first key expires or the first key corresponding to the identification information of the information processing units 14 is not stored, the key sharing part 202 shares the first key with the information processing units 14, and the cryptographic communicating part 208 performs the cryptographic communication with the information processing units 14 using a newly shared first key.

Claims9

Dependent claims

A communication support server for supporting cryptographic communication between communication terminals, comprising:

a communication condition storing part which stores communication conditions of the cryptographic communication performed by the communication terminals, in correspondence to identification information of the communication terminals, with respect to each of the communication terminals;
a key sharing part which shares a first key to be used for cryptographic communication with the communication terminals;
a first key storing part which stores the first key, which is shared by the key sharing part and the communication terminals, along with a term of validity corresponding to the first key, in correspondence to the identification information of the communication terminals;
a cryptographic communicating part which performs the cryptographic communication with the communication terminals having the identification information corresponding to the first key by using the first key;
a common communication condition extracting part which refers to the communication condition storing part by using the identification information of two of the communication terminals included in a communication initiation request received from the communication terminals through the cryptographic communicating part and extracts a common communication condition which is common to the two communication terminals;
and
a second key information creating part which creates second key information according to the extracted common communication condition and transmits the created second key information with the common communication condition to each of the two communication terminals through the cryptographic communicating part,
wherein when a request for the cryptographic communication to the communication terminals is made by the cryptographic communicating part, if the request is made before expiration of the term of validity of the first key corresponding to the identification information of the communication terminals, the request for the cryptographic communication to the communication terminals is made by using the first key in correspondence to the identification information of the communication terminals and stored in the first key storing part, and
if the request is made after the expiration of the term of validity of the first key or if the first key corresponding to the identification information of the communication terminals is not stored in the first key storing part, the cryptographic communicating part causes the key sharing part to share the first key, so that the request for the cryptographic communication to the communication terminals is made by using a newly shared first key.

6 more elements

A communication support method for supporting cryptographic communication between communication terminals by using a communication support server which includes a communication condition storing part storing communication conditions of the cryptographic communication performed by the communication terminals, in correspondence to identification information of the communication terminals and a first key storing part which stores a first key, to be used for cryptographic communication with the communication terminals, along with a term of validity corresponding to the first key, in correspondence to the identification information of the communication terminals, the communication support method comprising;

a communication initiation request acquiring step of decrypting an encrypted communication initiation request received from the communication terminals by using the first key in correspondence to the identification information of the communication terminals and stored in the first key storing part and acquiring the communication initiation request which includes the identification information of the two communication terminals initiating the cryptographic communication;
a common communication condition extracting step of referring to the communication condition storing part by using the identification information of the two communicating communication terminals included in the acquired communication initiation request and extracting a common communication condition which is common to the two communicating communication terminals;
a second key information creating step of creating second key information according to the extracted common communication condition;
a second key information transmitting step of encrypting the extracted common communication condition and the created second key information by using the first key corresponding to the identification information of the communication terminals for each of the two communication terminals included in the communication initiation request and transmitting the encrypted common communication condition and the second key information;
and
a key sharing step, performed prior to the communication initiation request acquiring step and the second key information transmitting step, of sharing the first key and storing a newly shared first key, along with the term of validity of the first key in the first key storing part, in correspondence to the identification information of the communication terminals, when the term of validity of the first key expires, and when the first key corresponding to the identification information of the communication terminals is not stored in the first key storing part.

3 more elements

A communication support system for supporting cryptographic communication between communication terminals, comprising:

a plurality of communication terminals;
and
a communication support server which supports the cryptographic communication between the communication terminals,
wherein each of the plurality of communication terminals comprises:
a terminal side key sharing part which shares a first key to be used for cryptographic communication with the communication support server;
a terminal side first key storing part which stores the first key in correspondence to a term of validity of the first key;
a terminal side cryptographic communicating part which performs the cryptographic communication with the communication support server by using the first key;
a communication initiation request transmitting part which transmits identification information of a communication terminal transmitting a communication initiation request and a communication terminal of a communication counterpart along with a communication initiation request to the communication support server through the terminal side cryptographic communicating part;
a second key information receiving part which receives second key information which is a second key used for the cryptographic communication between the communication terminal transmitting a communication initiation request and the communication terminal of the communication counterpart, and which is seed information for producing the second key, in response to the communication initiation request transmitted from the communication initiation request transmitting part along with the identification information;
a second key storing part which stores the second key information received by the second key information receiving part, in correspondence to the identification information of the communication terminal of the communication counterpart;
and
an inter-terminal cryptographic communicating part which performs the cryptographic communication with the communication terminal of the communication counterpart by using the second key when the second key information is the second key, while performing the cryptographic communication with the communication terminal of the communication counterpart by using the second key produced from the seed information when the second key information is the seed information,
wherein the communication support server comprises:
a communication condition storing part which stores communication conditions of the cryptographic communication performed by the communication terminals, in correspondence to identification information of the communication terminals, with respect to each of the communication terminals;
a server side key sharing part which shares a first key to be used for the cryptographic communication with the communication terminals;
a server side first key storing part which stores the first key, which is shared by the server side key sharing part with the communication terminals, along with the term of validity corresponding to the first key, in correspondence to the identification information of the communication terminals;
a server side cryptographic communicating part which performs the cryptographic communication with the communication terminals having the identification information corresponding to the first key by using the first key;
a common communication condition extracting part which refers to the communication condition storing part by using the identification information of two of the communication terminals included in the communication initiation request received from the communication terminals through the server side cryptographic communicating part and extracting a common communication condition common to the two of the communication terminals;
and
a second key information creating part which creates the second key information to be used for the cryptographic communication according to the extracted common communication condition and transmits the created second key information with the common communication condition to each of the two communication terminals through the server side cryptographic communicating part,
wherein when a request for the cryptographic communication to the communication support server is made by the terminal side cryptographic communicating part of the communication terminal,
if the request is before expiration of the term of validity of the first key corresponding to the first key, the request for the cryptographic communication to the communication support server is made by using the first key, and
if the request is after the expiration of the term of validity of the first key or if the first key is not stored in the terminal side first key storing part, the terminal side cryptographic communicating part of the communication terminal causes the terminal side key sharing part to shares the first key to be used for the cryptographic communication with the communication support server, so that the request for the cryptographic communication to the communication support server by using a newly shared first key, and
when a request for the cryptographic communication to the communication terminals is made by the server side cryptographic communicating part of the communication support server,
if the request is made before expiration of the term of validity of the first key corresponding to the identification information of the communication terminals, the request for the cryptographic communication to the communication terminals is made by using the first key corresponding to the identification information of the communication terminals, and
if the request is made after the term of validity of the first key corresponding to the identification information of the communication terminals or if the first key corresponding to the identification information of the communication terminals is not stored in the server side first key storing part, the server side cryptographic communicating part of the communication support server causes the key sharing part to share the first key, so that the request for the cryptographic communication to the communication terminals is made by using a newly shared first key.

23 more elements

Dependencies are inferred from the claim text.