Terminal device, group management server, network communication system, and method for generating encryption key
First Claim
1. A terminal device capable of transmitting and receiving information encrypted with other terminal devices that belong to one group, comprising:
- a key storage unit storing a group encryption key and deletion keys, the group encryption key for encrypting and decrypting information transmitted and received with other terminal devices that belong to the group, and the deletion keys corresponding to each of the other terminal devices; and
an update unit generating, if there is a leaving terminal device among the other terminal devices that belong to the group, an updated group encryption key corresponding to a new group encryption key, from the deletion key corresponding to the leaving terminal device and the group encryption key stored in the key storage unit.
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Abstract
A network communication system has terminal devices belonging to a group, the terminal devices generating, if there is a leaving terminal device leaving from the group, an updated group encryption key corresponding to a new group encryption key, from a deletion key corresponding to the leaving terminal device and a group encryption key, and, after the leaving terminal device leaves the group, communicating by using the updated group encryption key; and a group management server generating the updated group encryption key corresponding to the new group encryption key from the deletion key corresponding to the leaving terminal device and the group encryption key, and, after the leaving terminal device leaves the group, communicating by using the updated group encryption key.
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Citations
9 Claims
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1. A terminal device capable of transmitting and receiving information encrypted with other terminal devices that belong to one group, comprising:
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a key storage unit storing a group encryption key and deletion keys, the group encryption key for encrypting and decrypting information transmitted and received with other terminal devices that belong to the group, and the deletion keys corresponding to each of the other terminal devices; and an update unit generating, if there is a leaving terminal device among the other terminal devices that belong to the group, an updated group encryption key corresponding to a new group encryption key, from the deletion key corresponding to the leaving terminal device and the group encryption key stored in the key storage unit. - View Dependent Claims (2)
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3. A group management server capable of transmitting a group encryption key and deletion keys to terminal devices, the group encryption key for use in encryption of a communication with other terminal devices that belong to the group, and the deletion keys corresponding to the terminal devices that belong to the group, the server comprising:
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a key storage unit storing the deletion keys corresponding to the terminal devices that belong to the group, and the group encryption key; and an update unit generating, if a terminal device leaves the group, an updated group encryption key corresponding to a new group encryption key, from the deletion key corresponding to the leaving terminal device and the group encryption key stored in the key storage unit. - View Dependent Claims (4, 5, 6)
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7. A network communication system comprising:
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terminal devices belonging to a group, the terminal devices generating, if there is a leaving terminal device leaving from the group, an updated group encryption key corresponding to a new group encryption key, from a deletion key corresponding to the leaving terminal device and a group encryption key, and, after the leaving terminal device leaves the group, communicating by using the updated group encryption key; and a group management server generating the updated group encryption key corresponding to the new group encryption key from the deletion key corresponding to the leaving terminal device and the group encryption key, and, after the leaving terminal device leaves the group, communicating by using the updated group encryption key. - View Dependent Claims (8)
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9. A method for generating an encryption key in a group including a plurality of terminal devices where a communication is encrypted with a group encryption key with other terminal devices within the group, and if there is a leaving terminal device that leaves the group, an updated group encryption key corresponding to a new group encryption key is generated, the method comprising the steps of:
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generating a first value from the existing group encryption key by using a predetermined function; generating a second value from the deletion key corresponding to the leaving terminal device by using a predetermined function; and generating the updated group encryption key corresponding to a new group encryption key, from the first value and the second value by using a predetermined function.
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Specification