Sensor network, sensor management server, key updating method and key updating program

Patent metadata

Field	Value
Publication number	US-9363668-B2
Application number	US-201314377886-A
Country	US
Kind code	B2
Filing date	Jan 30, 2013
Priority date	Feb 9, 2012
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

A sensor network includes a sensor management server which is mutually connected with many sensor terminals. The sensor management server includes: a key delivery module for transmitting a key update message to the respective sensor terminals; a communication volume detection module for detecting a communication volume used for transmitting the key update message; and a multiplicity determination module for specifying a numerical value as a multiplicity, which represents the lower limit number of key update messages transmitted to the respective sensor terminals, according to the detected communication volume. The multiplicity determination module specifies the multiplicity such that the communication volume for transmitting or retransmitting the key update message takes the minimum value, and the key delivery module transmits the key update message by using the minimum communication volume that corresponds to the specified multiplicity.

First claim

The invention claimed is:

1. A sensor network comprising:
plural sensor terminals operatively connected to the sensor management server, each said sensor terminal storing an element key; and
a sensor management server operatively connected to each of the sensor terminals,
wherein the sensor management server transmits a key update message to each of the sensor terminals, and each of the sensor terminals i) updates the element key according to the received key update message, and ii) performs encrypted communication with the sensor management server by utilizing the element key,
wherein the sensor management server comprises:
i) a key delivery module which transmits the key update message, a multiplicity of times, from the sensor management server to each of the sensor terminals, the multiplicity being defined as a lower limit value of a number of the key update messages to be transmitted to each of the sensor terminals,
ii) a communication volume detection module which detects a communication volume when transmitting the key update message from the key delivery module to each of the sensor terminals, and
iii) a multiplicity determination module which specifies, based on the detected communication volume, a numerical value of the multiplicity to thereby specify the number of the key update messages that the key delivery module transmits to each of the sensor terminals,
wherein the multiplicity determination module specifies the numerical value of the multiplicity corresponding to where the communication volume when transmitting the key update message becomes a minimum value, and the key delivery module transmits the key update message with a minimum communication volume that corresponds to the numerical value of the multiplicity specified by the multiplicity determination module.

2. The sensor network as claimed in claim 1 , wherein
the multiplicity determination module includes a function which sets number of attributes of each of the sensor terminals as an initial value of the multiplicity and, thereafter, successively decreases the multiplicity until the communication volume when transmitting the key update message turns to increase from decrease.

3. The sensor network as claimed in claim 1 , wherein
each of the sensor terminals comprises a key reception module which receives the key update message, and a key update module which updates the element key according to information acquired by decrypting the received key update message.

4. The sensor network as claimed in claim 3 , wherein:
each of the sensor terminals comprises a retransmission key setting module which requests retransmission of the key update message when the key update message with which the element key can be updated cannot be received;
the sensor management server comprises a key retransmission module which transmits information required for updating the element key in response to the retransmission request; and
the retransmission key setting module of each of the sensor terminals includes a function which receives the transmitted information required for updating the element key and updates the element key based thereupon.

5. The sensor network as claimed in claim 1 , wherein
the key delivery module of the sensor management server includes a function which repeats processing for selecting the sensor terminals that correspond to a specific attribute among each of the sensor terminals and transmitting the key update message to those sensor terminals until the multiplicity reaches a numerical value specified by the multiplicity determination module.

6. The sensor network as claimed in claim 5 , wherein
the key delivery module of the sensor management server includes a function which transmits the key update message by excluding the specific sensor terminal designated as an out-of-target terminal for updating the key among each of the sensor terminals.

7. A sensor management server connected mutually with a large number of sensor terminals each storing an element key, wherein the sensor management server transmits a key update message to each of the sensor terminals for i) the sensor terminals updating the element key to each of the sensor terminals and ii) performing encrypted communication with each of the sensor terminals by utilizing the element key, the sensor management server comprising:
a key delivery module which transmits the key update message, a multiplicity of times, to each of the sensor terminals, the multiplicity being defined as a lower limit value of a number of the key update messages to be transmitted to each of the sensor terminals;
a communication volume detection module which detects a communication volume when transmitting or retransmitting the key update message from the key delivery module to each of the sensor terminals, and
a multiplicity determination module which specifies, based on the detected communication volume, a numerical value of the multiplicity to thereby specify the number of the key update messages that the key delivery module transmits to each of the sensor terminals,
wherein the multiplicity determination module successively specifies the multiplicity with which the detected communication volume when transmitting or retransmitting the key update message becomes a minimum value, and the key delivery module successively transmits the key update message according to the specified multiplicity such that the communication volume when transmitting or retransmitting the key update message is the minimum value.

8. A key updating method used in a sensor network comprising a large number of sensor terminals each storing an element key and a sensor management server connected mutually with each of the sensor terminals, the method comprising:
the sensor management server transmitting a key update message, a multiplicity of times, to each of the sensor terminals, the multiplicity being defined as a lower limit value of a number of the key update messages to be transmitted to each of the sensor terminals; and
each of the sensor terminals i) updating the element key according to the received key update message and ii) performing encrypted communication with the sensor management server by utilizing the element key, wherein:
a multiplicity determination module of the sensor management server initially sets an initial numerical value of the multiplicity to set an initial number of the key update messages to be transmitted from the sensor management server to each of the sensor terminals;
a key delivery module of the sensor management server transmits the key update message to each of the sensor terminals according to the set initial numerical value of the multiplicity;
a communication volume detection module of the sensor management server detects a communication volume when transmitting or retransmitting the key update message from the key delivery module to each of the sensor terminals; and
the multiplicity determination module of the sensor management server specifies an updated numerical value of the multiplicity when transmitting the key update message plural next times according to the detected communication volume wherein, the multiplicity determination module determines a further numerical value of the multiplicity corresponding to where the communication volume, when transmitting the key update message the number of times corresponding to the further numerical value of the multiplicity, becomes a minimum value, and the key delivery module transmits the key update message with a minimum communication volume that corresponds to the determined further numerical value of the multiplicity specified by the multiplicity determination module.

9. A non-transitory computer readable recording medium storing a key updating pro

Assignees

• Nec Corp

Inventors

• Noda Jun

Classifications

• H04L9/14

  using a plurality of keys or algorithms · CPC title

• H04L2209/24

  Key scheduling, i.e. generating round keys or sub-keys for block encryption · CPC title

• H04L9/0891

  Revocation or update of secret information, e.g. encryption key update or rekeying · CPC title

• H04W84/18

  Self-organising networks, e.g. ad-hoc networks or sensor networks · CPC title

• H04L9/083 Primary

  involving central third party, e.g. key distribution center [KDC] or trusted third party [TTP] · CPC title