JP2004056762A - Wireless communication method and equipment, communication control program and controller, key management program, wireless lan system, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To construct, at low cost regardless of system scale, a wireless LAN system which is safe in both the aspects of terminal authentication and protection of communication contents. <P>SOLUTION: An access point 22a and a terminal 25a share a secret key Ks. The access point 22a generates a cryptographic key K to be used for encrypting/decoding the communication contents by itself, encrypts the key with the secret key Ks and then transfers it to the terminal 25a. The terminal 25a decodes the encrypted and transferred secret key Ks to be reproduced. The access point 22a and the terminal 25a respectively generates an encrypted data stream from the shared cryptographic key K and confirm that the encrypted data stream is to be shared. Thereafter, contents of communications between the both are encrypted/decoded, using the encrypted data stream. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a wireless communication method of a wireless LAN, various devices and programs used for realizing the method, and a wireless LAN system constructed by those devices.
[0002]
[Prior art]
In recent years, a wireless LAN system that can easily realize a wireless network environment has attracted attention, and companies that introduce a wireless LAN to an in-house network are increasing.
[0003]
FIG. 13 shows a configuration of a general wireless LAN system. The wireless LAN system includes an access point device (hereinafter, simply referred to as an access point) 1 and terminal devices (hereinafter, simply referred to as terminals) 2a, 2b, 2c permitted to communicate with the access point 1.
[0004]
Each of the access point 1 and the terminals 2a, 2b, and 2c has a function of converting digital data into a radio wave 10 and transmitting and receiving it. As the terminals 2a, 2b, and 2c, those having such functions added by inserting a wireless LAN card into a personal computer are often used. The access point 1 is originally a device having such a function, but the inside of the main body often includes a combination of a wireless LAN card and a control board for controlling the wireless LAN card. The terminals 2a, 2b, and 2c can perform wireless communication with each other via the access point 1.
[0005]
The access point 1 is provided with a port 9 for connecting a cable, and is often connected to a wired network such as a wired LAN or the Internet. When the access point 1 is connected to a wired network, the access point 1 converts a wireless packet received from the terminal 2a, 2b, 2c into a wired packet and sends the packet to the wired network. Thus, the terminals 2a to 2c can communicate with other computers on the wired network.
[0006]
In the wireless LAN system, it is necessary to prevent a terminal 5 not permitted to communicate with the access point 1 from accessing the wired network via the access point 1. Further, since the radio wave 10 passes through the wall of the building 8 and is transmitted to the outside, the communication packet exchanged between the terminals 2a, 2b, 2c and the access point 1 is prevented from being eavesdropped by the external terminal 6. You also need to do it. That is, for the wireless LAN system, the terminal authentication function and the function of keeping communication contents secret are essential functions.
[0007]
Many of the wireless LAN products currently on the market conform to the international standard IEEE 802.11 of wireless LAN. FIG. 14 is a diagram for describing an authentication and concealment method based on IEEE 802.11.
[0008]
In IEEE 802.11, in order to authenticate a terminal, a MAC address of a terminal to which communication is permitted is registered in the access point 1 in advance. The MAC address is data set in the device from the time of manufacture as unique data for identifying the communication device. Normally, 48-bit data obtained by combining a code indicating an apparatus maker and a serial number managed by the maker is set as a MAC address. In the header of the communication packet 11, a MAC address is set as information for specifying a transmission source and a transmission destination. The access point 1 verifies the source MAC address in the communication packet 11 with the MAC address of the registered terminal to authenticate whether the terminal that transmitted the communication packet is a terminal that has permitted communication.
[0009]
However, this method has a problem that a third party who knows the MAC address by eavesdropping a communication packet or the like can set the MAC address in its own terminal and pretend to be a registered terminal, that is, a so-called "spoofing" is possible. Has been pointed out.
[0010]
In IEEE 802.11, communication contents are concealed by an encryption function called WEP (Wired Equivalent Privacy). In WEP, 40-bit encryption key data K is generated in advance, and the encryption key data K is registered in the access point 1 and the terminals 2a, 2b, and 2c in advance. Further, each of the terminals 2a, 2b, 2c and the access point 1 internally generates a 24-bit key called an initial vector (IV) each time a packet is transmitted. The communication content is encrypted using only the encryption key data K or both the encryption key data K and IV, and is decrypted after the transfer. The initial vector is stored in the communication packet 11 together with the encrypted data.
[0011]
However, since many of the products on the market at present have the user manually set and register the encryption key data K, the once set encryption key data K is often used for a long period of time. It is also said that the initial vector can be easily known by intercepting a communication packet and is as short as 24 bits, so that if radio waves are intercepted and analyzed for several hours, the communication contents can be decoded.
[0012]
IEEE 802.1x has been proposed as a standard for solving the security problem of IEEE 802.11. IEEE 802.1x is a standard for a system having a configuration as shown in FIG. 15, for example. The system in FIG. 15 is an in-house LAN system of a company in which a wireless LAN is partially introduced. The file server 12, the HUB 13 installed in the office, and the access point 14 installed in the conference room are all connected to a wired LAN 16. When working in the office, the user accesses the file server 12 by connecting the notebook computer 3 to the HUB 13 by cable, and uses the notebook computer 3 with the wireless LAN card 4 inserted therein as the terminal 15 when in the conference room. Then, the user accesses the file server 12 via the access point 14.
[0013]
In IEEE 802.1x, an authentication server 17 called a RADIUS server is installed on the wired LAN 16 as shown in FIG. The authentication server 17 authenticates a terminal connected to the wired LAN 16 via the HUB 13 and a terminal connected to the wired LAN 16 via the access point 14 in the same manner using the ID and the password.
[0014]
FIG. 16 is a diagram for explaining an IEEE 802.1x authentication procedure. In the authentication server 17, the ID of the terminal 15 or the user who uses the terminal 15 and the password for each ID are registered in advance. When the terminal 15 transmits a connection request to the access point 14, an authentication request is returned from the access point 14 to the terminal 15. When the ID and the password are input to the terminal 15, they are sent to the authentication server 17 via the access point 14. The authentication server 17 collates the received ID and password with the ID and password registered in the registration list 18 in advance, and notifies the terminal 15 that the authentication has been successful if the terminal has been registered. The access point 14 transmits an encryption key generated for each terminal and for each connection to the terminal authenticated by the authentication server 17 using the above-described password. Thereafter, the terminal 15 and the access point 14 use this encryption key to encrypt / decrypt communication contents.
[0015]
[Problems to be solved by the invention]
Wireless LAN products conforming to the IEEE 802.11 specifications are now widely and inexpensively provided, and although they have contributed to the spread of wireless LANs, security problems have been pointed out as described above.
[0016]
On the other hand, although IEEE 802.1x is improved in security, it is necessary to bear the cost of installing and managing an authentication server. That is, it is suitable for an in-house LAN of a large company, but is not suitable for a small-sized wireless LAN system composed of tens of personal computers. As one form of the wireless LAN system, there is a system in which each terminal only connects to the Internet via an access point (there is no wired LAN), but in this form, an authentication server cannot be installed.
[0017]
Therefore, it is desired to realize a wireless LAN system that can be constructed relatively inexpensively regardless of the scale of the system and that can secure sufficient security.
[0018]
[Means for Solving the Problems]
The present invention proposes a method for solving the above-mentioned problem, and provides various devices and programs used for realizing the method, and a wireless LAN system constructed by those devices.
[0019]
The wireless communication method proposed by the present invention provides a wireless communication method for a master wireless communication device that functions as an access point for wireless connection to a computer system, and at least one slave wireless communication device permitted to communicate with the wireless connection access point. Wireless communication method between
A predetermined secret key is shared between the master wireless communication device and the slave wireless communication device,
Generating an encryption key by the master wireless communication device;
The generated encryption key is encrypted using the secret key and transferred from the master wireless communication device to the slave wireless communication device,
On the slave wireless communication device side, by decrypting the transferred encryption key using the secret key, the master wireless communication device and the slave wireless communication device share the encryption key,
The method is characterized in that the shared encryption key is used for encrypting and decrypting communication data transmitted and received between a master wireless communication device and a slave wireless communication device.
[0020]
An encryption key may be used directly for encrypting and decrypting communication data, but an encrypted data stream generated by encrypting predetermined data using an encryption key can be used to encrypt and decrypt communication data. It may be used for chemical conversion. This is to speed up the processing during communication. At this time, a part of the encrypted data stream may be used for encrypting communication data, and the encrypted communication data may be transmitted with index data indicating the part. This is because decryption is made difficult by changing the portion used for encryption.
[0021]
In the above method, it is preferable that the generation, encryption, and transfer of the encryption key by the master wireless communication device are repeated at a predetermined timing, thereby updating the shared encryption key at that timing. Frequent key exchange makes decryption difficult. As the predetermined timing, when the power of the master wireless communication device is turned on, at a predetermined time, at a predetermined time interval, when communication is interrupted for a predetermined time or more, the number of slave wireless communication devices connected to the master wireless communication device becomes equal to or less than a predetermined number. And when there is an instruction from outside.
[0022]
As the secret key, a key generated and stored in a strictly controlled environment is preferably used. For example, the first password is generated by a predetermined key management device, is stored in the key management device in an encrypted state using a first password externally input to the key management device, and the first password is stored in the key management device. It is preferable to use a key that can be decrypted and used when input.
[0023]
In order to share a secret key between the master wireless communication device and at least one slave wireless communication device, for example, a secret key managed by a key management device may be shared by a master wireless communication device and a slave device that share the secret key. Each of the wireless communication devices is encrypted using its own unique data, and the encrypted secret key is transferred to the master wireless communication device and the slave wireless communication device corresponding to each unique data. The master wireless communication device or the slave wireless communication device on the transfer side may decode the data using the unique data of the wireless communication device.
[0024]
Alternatively, the secret key managed by the key management device is encrypted using the unique data of each of the master wireless communication device and the slave wireless communication device sharing the secret key, and / or the second password, and then encrypted. In the corresponding master wireless communication device or slave wireless communication device, the encrypted private key stored in the storage medium and read from the storage medium is stored in the unique data and / or the second password of the wireless communication device. , The secret key may be shared.
[0025]
At this time, the secret key is desirably stored in each of the master wireless communication device and the slave wireless communication device in an encrypted state using the unique data of each wireless communication device.
[0026]
The unique data may be data generated by encrypting wireless communication device identification data (for example, the MAC address of the device) that differs for each wireless communication device using a predetermined encryption method.
[0027]
Further, the slave wireless communication device encrypts the encryption key decrypted using the secret key again using the secret key and then transfers the encrypted key to the master wireless communication device. It is preferable to collate the encryption key encrypted using the secret key with the encryption key encrypted and transferred by the slave wireless communication device. This is because it is possible to confirm that the same private key is held.
[0028]
When sharing the encryption key with a plurality of slave wireless communication devices, the master wireless communication device may simultaneously transfer the encrypted encryption key to the plurality of slave wireless communication devices, It may be transferred.
[0029]
Also, the master wireless communication device may encrypt the slave wireless communication device located in the communication range of the master wireless communication device when power is turned on and / or when the slave wireless communication device located outside the communication range enters the communication range. Preferably, the encrypted encryption key is transferred to the slave wireless communication device.
[0030]
Note that the master wireless communication device may suspend transmission and reception of communication data with each slave wireless communication device until the encryption keys of all slave wireless communication devices are updated while the encryption key is being updated. The updated encryption key is used to transmit and receive communication data to and from the slave wireless communication device whose encryption key has been updated without interrupting the transmission and reception of communication data even during the encryption key update. May be used for transmission and reception of communication data with the slave wireless communication device for which the encryption key has not been completed yet.
[0031]
If the master wireless communication device receives communication data encrypted using the encryption key before update from any of the slave wireless communication devices while updating the encryption key, the master wireless communication device has priority over the slave wireless communication device. It is preferable to perform the update procedure in a comprehensive manner.
[0032]
The first wireless communication device of the present invention is a device used as a master wireless communication device in the above method. That is, a wireless communication device that functions as an access point for wireless connection to a computer system,
Secret key holding means for holding a predetermined secret key;
Encryption key generation means for generating an encryption key used for encryption and decryption of communication data,
Key encryption means for encrypting the encryption key generated by the encryption key generation means using the secret key held by the secret key holding means;
Transfer means for transferring the encryption key encrypted by the key encryption means to another wireless communication device holding the same secret key as the secret key;
Data transmission / reception means for transmitting / receiving communication data encrypted with an encryption key to / from the other wireless communication device.
[0033]
It is preferable that the data transmission / reception unit is a unit that uses an encrypted data stream generated by encrypting predetermined data using an encryption key for encrypting and decrypting communication data. At this time, the data transmission / reception unit may use a part of the encrypted data stream for encryption, and transmit the encrypted communication data with index data indicating the part.
[0034]
The first wireless communication device updates the shared encryption key at the above-mentioned timing by repeating the generation of the encryption key by the encryption key generation unit, the encryption by the key encryption unit, and the transfer by the transfer unit at a predetermined timing. Is preferred.
[0035]
Further, the first wireless communication device uses the same secret key as an encryption key encrypted by itself using the secret key and an encryption key decrypted by the wireless communication device to which the encryption key has been transferred using the secret key. It is preferable that the apparatus further includes a collation unit that collates the encrypted data with the data returned to the first wireless communication device. As the predetermined timing, when the power of the master wireless communication device is turned on, at a predetermined time, at a predetermined time interval, when communication is interrupted for a predetermined time or more, the number of slave wireless communication devices connected to the master wireless communication device becomes equal to or less than a predetermined number. And when there is an instruction from outside.
[0036]
Preferably, the secret key holding means is means for storing a secret key encrypted using the unique data of the first wireless communication device. As the unique data, data generated by encrypting the identification data of the first wireless communication device by a predetermined encryption method, or the like can be considered.
[0037]
The transfer means may be a means for simultaneously transferring the encrypted encryption key or a means for sequentially transferring the encrypted encryption key when transferring the encrypted encryption key to the plurality of other wireless communication devices. The transfer unit is configured to encrypt the encrypted cipher when the power of the slave wireless communication device arranged in the communication area of the master wireless communication apparatus is turned on and / or when the slave wireless communication apparatus arranged outside the communication area moves into the communication area. Preferably, the key is transferred to the slave wireless communication device.
[0038]
The data transmitting / receiving means transmits / receives the communication data when transmitting / receiving the communication data to / from any of the slave wireless communication devices while the encryption key is being updated by the encryption key generation means, the key encryption means, and the transfer means. It may be interrupted, the communication data is transmitted and received even during the update of the encryption key, and the updated encryption key is used for transmission and reception of communication data with another wireless communication device whose encryption key has been updated, The encryption key before the update may be used for transmission and reception of communication data with another wireless communication device for which the update of the encryption key is not completed.
[0039]
If the data transmission / reception unit receives communication data encrypted using the encryption key before the update while the encryption key is being updated by the encryption key generation unit, the key encryption unit, and the transfer unit, the encryption is performed. It is preferable that the key generation unit, the key encryption unit, and the transfer unit preferentially perform the update procedure on the wireless communication device that is the source of the communication data.
[0040]
Also, the first wireless communication device is a wireless communication device whose access permission to the computer system has been canceled among other wireless communication devices holding the same secret key as the secret key held by the first wireless communication device. Communication rejection target storage means for storing the communication rejection target, and communication rejection means for rejecting execution of processing necessary for transmitting and receiving communication data with the wireless communication device stored as the communication rejection target by the communication rejection target storage means. , Is preferably provided. Here, the processing required for transmission and reception of communication data is, specifically, an encryption key generation processing, an encryption key transfer processing, a data transmission processing, a reception processing, a belonging processing, and the like.
[0041]
Next, a second wireless communication device of the present invention is a device used as a slave wireless communication device in the method of the present invention. That is, a wireless communication device that performs wireless communication with a wireless connection access point to the computer system,
Secret key holding means for holding a predetermined secret key;
Key decryption means for encrypting the wireless connection access point using the same secret key as the secret key and transferring the encryption key transferred to the wireless communication device, using the secret key held by the secret key holding means; ,
Data transmission / reception means for transmitting / receiving communication data encrypted using the encryption key decrypted by the key decryption means to / from the wireless connection access point.
[0042]
However, the function of the slave wireless communication device can be realized by software. The communication control program according to the present invention is a communication control program that controls a communication function of a slave wireless communication device that performs wireless communication with a master wireless communication device that functions as an access point for wireless connection to a computer system. Wireless communication device,
Secret key holding means for holding a predetermined secret key;
Key decryption means for encrypting the master wireless communication device using the same secret key as the secret key and transferring the encrypted key to the slave wireless communication device using the secret key held by the secret key holding means,
A communication control program for functioning as a data transmitting / receiving means for transmitting / receiving communication data encrypted with the master wireless communication device using the encryption key decrypted by the key decrypting means.
[0043]
Such a communication control program can be recorded on various recording media and distributed. It can also be distributed over a network.
[0044]
Further, the function of the slave wireless communication device may be realized by hardware, such as a wireless LAN card, which functions as a unit with the processing device by being inserted into a processing device such as a personal computer. The communication control device of the present invention is a communication control device that controls a communication function of a slave wireless communication device that performs wireless communication with a master wireless communication device that functions as an access point for wireless connection to a computer system,
Secret key holding means for holding a predetermined secret key;
Key decryption means for encrypting the master wireless communication device using the same secret key as the secret key and transferring the encrypted key to the slave wireless communication device using the secret key held by the secret key holding means,
Data transmission / reception means for transmitting / receiving communication data encrypted with the master wireless communication apparatus using the encryption key decrypted by the key decryption means.
[0045]
Either when the slave wireless communication device is provided as a dedicated device, when the function of the slave wireless communication device is realized by software, or when the function of the slave wireless communication device is realized by an embedded control device such as a wireless LAN card. In this case, it is preferable that the data transmission / reception unit is a unit that uses an encrypted data stream generated by encrypting predetermined data using an encryption key for encrypting and decrypting communication data. At this time, the data transmission / reception means may use a part of the encrypted data stream for encryption, and transmit the encrypted communication data with index data indicating the part.
[0046]
Also, when the slave wireless communication device is provided as a dedicated device, when the function of the slave wireless communication device is realized by software, or when the function of the slave wireless communication device is realized by a built-in control device such as a wireless LAN card. In any case, the secret key holding means may be a means for storing a secret key encrypted using the unique data of the wireless communication device. As the unique data, data generated by encrypting the identification data of the wireless communication device by a predetermined encryption method or the like can be considered.
[0047]
The function of the slave wireless communication device can be realized by both hardware and software. For example, a mode in which some of the functions of the slave wireless communication device are provided as functions of a wireless LAN card and some of the other functions are provided by driver software for the wireless LAN card is conceivable. In this case, the driver software is provided by being recorded on the following recording medium.
[0048]
The recording medium is a recording medium on which a communication control program for controlling a communication function of a slave wireless communication device that performs wireless communication with a master wireless communication device that functions as an access point for wireless connection to a computer system is recorded. And the slave wireless communication device,
A program functioning as secret key holding means for holding a predetermined secret key;
The master wireless communication device functions as key decryption means for encrypting using the same secret key as the secret key and decrypting the encryption key transferred to the slave wireless communication device using the secret key held by the secret key holding means. Program to be
A computer-readable storage medium storing at least one program for functioning as a data transmission / reception unit for transmitting / receiving communication data encrypted using the encryption key decrypted by the key decryption unit with the master wireless communication device. It is a possible recording medium.
[0049]
Next, the key management program of the present invention is a program for setting a secret key in each device. In the method of the present invention, this is a program used when the master wireless communication device and the slave wireless communication device share a predetermined secret key. Two types of programs are proposed according to the key setting method.
[0050]
The first key management program is provided in both a wireless communication device of a master wireless communication device functioning as an access point for wireless connection to a computer system and a slave wireless communication device permitted to communicate with the wireless connection access point. On the other hand, a key management program for setting a common secret key,
A device-specific encryption function for encrypting a predetermined secret key using unique data of a wireless communication device for setting the secret key,
This is a key management program for realizing a secret key transfer function of transferring a secret key encrypted by the device-specific encryption function to each wireless communication device corresponding to the unique data used for encryption.
[0051]
In addition, the second key management program includes two wireless communication devices: a master wireless communication device that functions as an access point for wireless connection to the computer system; and a slave wireless communication device that is permitted to communicate with the wireless connection access point. In contrast, a key management program for setting a common secret key,
A device-specific encryption function for encrypting a predetermined secret key using unique data of a wireless communication device for setting the secret key and / or a second password;
This is a key management program for realizing an external output function of storing a secret key encrypted by the device-specific encryption function in a predetermined storage medium.
[0052]
In each of the first and second key management programs, the computer further includes:
A key generation function for generating a secret key,
The secret key generated by the key generation function is encrypted using a first password input from the outside, and then stored in the computer. The secret key storage function stores the secret key in the computer, and the first password is input to the computer. In such a case, a secret key reading function for decrypting the secret key stored by the secret key storage function to make it usable can be added.
[0053]
In the wireless LAN system of the present invention, the first wireless communication device of the present invention is used as a master wireless communication device, and the second wireless communication device of the present invention or the general-purpose processing device is provided with a communication control program of the present invention. A wireless LAN system that performs wireless communication based on the method of the present invention using a device incorporating a communication control device as a slave wireless communication device.
[0054]
That is, the wireless LAN system of the present invention includes a master wireless communication device that functions as an access point for wireless connection to a computer system, and at least one slave wireless communication device permitted to communicate with the wireless connection access point. A wireless LAN system comprising:
The master wireless communication device,
Master-side secret key holding means for holding a predetermined secret key;
Encryption key generation means for generating an encryption key used for encryption and decryption of communication data,
Key encryption means for encrypting the encryption key generated by the encryption key generation means using the secret key held by the secret key holding means;
Transfer means for transferring the encryption key encrypted by the key encryption means to a slave wireless communication device holding the same secret key as the secret key;
Master-side data transmission / reception means for transmitting / receiving communication data encrypted using the encryption key to / from the wireless communication device to which the transfer means has transferred the encryption key,
The slave wireless communication device is
Slave-side secret key holding means for holding the same secret key as the master wireless communication device;
Key decryption means for decrypting the encryption key transferred from the transfer means of the master wireless communication device using the secret key held by the slave side secret key holding means,
A slave data transmission / reception unit for transmitting / receiving communication data encrypted with the master wireless communication device using the encryption key decrypted by the key decryption unit.
[0055]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
[0056]
1. Overview of wireless LAN system and overview of wireless communication method
First, as an embodiment of the wireless LAN system of the present invention, FIG. 1 shows an example of an in-house LAN system in which a wireless LAN is partially introduced. The system includes a server computer 20, a group of personal computers 21a, access points 22a and 22b connected to a wired network 19, and terminals 25a and 25b and a wireless bridge 25c capable of communicating with the wired network 19 via the access points 22a and 22b. And a personal computer group 21b connected to the wireless bridge 25c. The personal computer groups 21a and 21b are respectively composed of HUBs 24a and 24b and a plurality of personal computers 23a and 23b and 23c to 23f connected to them by cables.
[0057]
Each of the access points 22a and 22b, the terminals 25a and 25b, and the wireless bridge 25c has a function (hereinafter, referred to as a wireless communication function) of converting communication data into radio waves and transmitting and receiving the radio waves. The wireless communication function may be a function originally provided in each device or a function added later.
[0058]
For example, the terminals 25a and 25b of the present embodiment insert the wireless LAN cards 27a and 27b into the notebook computers 26a and 26b, respectively, and install driver software for controlling the wireless LAN cards 27a and 27b, respectively. A wireless communication function is added later. Other examples of such a device include a device in which a wireless LAN card is inserted in a personal digital assistant (PDA), and a device in which a wireless LAN control board is incorporated in a desktop personal computer.
[0059]
On the other hand, the access points 22a and 22b and the wireless bridge 25c of the present embodiment are dedicated devices having a wireless communication function. However, the actual structure is such that a wireless LAN card and a control board for controlling the card are incorporated in the housing, and the wireless LAN card and the wireless communication are performed by a program stored in ROM on the control board. Function is realized. Other examples of such a device include a wireless HUB and a wireless router.
[0060]
The wireless communication function of the access points 22a and 22b enables mutual communication between the terminals 25a and 25b, access from the terminals 25a and 25b to the server computer 20, communication between the personal computers 23c to 23f of the personal computer group 21b and the personal computers 23a and 23b of the personal computer group 21a. And the like are realized. As shown in the figure, the terminal 25b can communicate with both the access points 22a and 22b. The terminal 25a and the wireless bridge 25c can use any of the access points 22a and 22b.
[0061]
Hereinafter, as one embodiment of the wireless communication method of the present invention, a communication method between the access point 22a and the terminal 25a in FIG. 1 will be described as an example. However, as described above, a device that performs wireless communication with an access point is not necessarily a terminal that is directly operated by a user, and there is a relay device such as the wireless bridge 25c. The wireless communication method of the present invention is a wireless communication method for any device including such a relay device, and the following description does not limit the scope of the present invention.
[0062]
The access point 22a and the terminal 25a perform encrypted communication using the shared encryption key after going through two steps of "shared secret key" and "shared encryption key". The “encryption key” is a key used for encrypting communication contents, and the “secret key” is a key for encrypting the encryption key. The term "shared" means that the access point 22a and the terminal 25a each hold the same key internally.
[0063]
First, a procedure for sharing a secret key will be described with reference to FIG. In the present embodiment, the secret key Ks is generated by a key management program incorporated in the management computer 28 used by the system administrator.
[0064]
Next, the management computer 28 and the access point 22a are connected by the cable 30 so as to be in a state where direct communication is possible. The cable 30 may be any of general-purpose connection cables such as an Ethernet (registered trademark), a USB cable, and an RS232C cable. Then, the generated secret key Ks is transferred from the administrator computer 28 to the access point 22a via the cable 30. As a result, the secret key Ks is set in the access point 22a. The secret key Ks can be set not only for the access point 22a but also for the access point 22b and the wireless bridge 25c by this procedure.
[0065]
Next, the generated secret key Ks is recorded on the recording medium 29. The recording medium 29 may be a medium capable of storing and holding data, and may be a floppy (registered trademark) disk, an MO, a CDR, a tape, or the like. The terminal 25a reads the secret key Ks from the recording medium 29 and stores it inside. As a result, the secret key Ks is set in the terminal 25a. The secret key Ks can be set not only in the terminal 25a but also in the terminal 25b by this method.
[0066]
As a means for delivering the secret key Ks, besides cable connection and delivery using a recording medium, wireless communication using infrared rays and any other data delivery means can be used. However, when setting the secret key for the first time, it is not possible to authenticate whether the setting destination device is authorized for access to the access point. Is preferred.
[0067]
Next, a procedure for sharing an encryption key will be described with reference to FIG. The access point to which the secret key Ks is set thereafter generates and distributes the encryption key K autonomously, that is, independently of any other device. Each of the access points 22a and 22b generates an arbitrary encryption key K, and encrypts the generated encryption key K with a secret key Ks. In this embodiment, an encryption method RC5 developed by RSA is used as an encryption method (hereinafter, referred to as an encryption function RC5).
[0068]
After that, each of the access points 22a and 22b transfers the encryption key K encrypted with the secret key Ks to the terminals 25a and 25b and the wireless bridge 25c. This transfer is performed by wireless transmission. The terminals 25a and 25b and the wireless bridge 25c extract the encrypted encryption key K transferred from each of the access points 22a and 22b by decrypting the encrypted encryption key K using the secret key Ks set by the above-described procedure.
[0069]
FIG. 4 is a diagram showing the entire procedure according to the wireless communication method of the present invention. This figure shows the sharing of the secret key in FIG. 2, the sharing of the encryption key in FIG. 3, and the subsequent communication processing, focusing on the exchange between the access point 22a and the terminal 25a. The left side of the figure shows the processing of the access point 22a, the right side of the figure shows the processing of the terminal 25a, and the center arrow shows the data exchanged between them.
[0070]
As shown in the figure, a 128-bit secret key Ks is first shared between the access point 22a and the terminal 25a by a secret key sharing procedure. The access point 22a generates an arbitrary 128-bit encryption key K, and encrypts the encryption key K with the secret key Ks using the encryption function RC5. The encrypted encryption key K is transferred to the terminal 25a. The terminal 25a decrypts and extracts the encrypted encryption key K with the secret key Ks. According to the above procedure, the encryption key K is shared between the access point 22a and the terminal 25a.
[0071]
Here, in the present embodiment, instead of directly using the shared encryption key K for encrypting communication contents, predetermined data is encrypted with the encryption key K and data of a predetermined length (hereinafter, referred to as “ Is referred to as an encrypted data stream), and a logical operation (EXOR) of the encrypted data stream and communication data is performed to encrypt and decrypt communication contents. This is to speed up the encryption and decryption processes. In general, when input data is encrypted with a predetermined function (in this case, RC5), complicated calculations are required, and the data transfer rate in communication may be deteriorated. On the other hand, the logical operation of the two data is a relatively simple process and the calculation time may be short. Therefore, if an encrypted data stream is generated in advance and an EXOR of the input data and the encrypted data stream is used, the processing time for encryption and decryption can be reduced, and the data transfer rate can be reduced. Drops can be avoided.
[0072]
Therefore, the access point 22a and the terminal 25a of the present embodiment respectively generate an encrypted data stream from the shared encryption key K as shown in FIG. The encrypted data stream generated by the access point 22a and the encrypted data stream generated by the terminal 25a are the same because they are generated using the same encryption key K.
[0073]
The access point 22a and the terminal 25a confirm that the encrypted data stream can be shared, and thereafter, each of the data to be transmitted to the other party is encrypted by taking an exclusive OR with the encrypted data stream, and the data received from the other party is encrypted. Similarly, the data is decrypted by taking an EXOR with the encrypted data stream, and encrypted communication is performed.
[0074]
FIG. 5 is a diagram for explaining the encryption of communication data using the encrypted data stream. In order from the top, the encrypted data stream 34, the communication packet 35 generated by the terminal 25a, and the like, and the encrypted packet 36, a wireless LAN packet 37. In the present embodiment, a part of the range 38 of the encrypted data stream 34 is used for encrypting the communication packet 35.
[0075]
In the illustrated example, the packet 35 is a 1536-byte data stream obtained by adding a MAC header and a frame check sequence (FCS) to data to be transmitted. The portion other than the MAC header (referred to as an encryption target) is encrypted. Specifically, as shown in the figure, a logical operation EX- is performed between a range 38 having the same length as the encryption target after the head position specified as the offset of the encrypted data stream 34 and the encryption target. Perform an OR.
[0076]
As shown in the figure, the encrypted packet 36 is a 2304-byte data stream in which control data C, offset data OF, a MAC header, and the like are added to the encrypted data 39.
[0077]
Finally, as shown in the figure, data IV, ICV, and the like necessary for the conventional encryption method standardized in the wireless LAN system are further added and transmitted as the wireless LAN packet 37.
[0078]
Offset data OF indicating the head position of the range 38 used for encryption is added to the encrypted data 39 and transferred together with the encrypted data 39. The offset data OF is changed for each communication (for each communication packet). Therefore, the range 38 used for encrypting the encrypted data stream differs for each communication packet. For example, assuming that the length of the encrypted data stream is 2 Mbytes, a 21-bit offset data storage area is required so that all positions can be designated as the start position of the range 38 (2). ²¹ = About 2M ways). In the present embodiment, an area of a total of 24 bits obtained by adding 3 dummy bits to 21 bits is reserved for offset data. However, the length of the encrypted data stream is not limited to 2 Mbytes, and any length can be selected. The number of bits of the offset data OF may be determined so that all bits of the encrypted data stream 34 can be specified.
[0079]
As described above, even if the number of encrypted data streams generated from the encryption key K is one, if the range 38 used for encrypting the encrypted data stream is changed for each communication, there are practically any number of types. This is the same as performing the encryption, and it becomes extremely difficult for a third party who eavesdrops on the communication packet to decrypt the encrypted data 39.
[0080]
In this case, if the encrypted data streams are exchanged as needed, instead of using one encrypted data stream, it is more secure. Therefore, in the present embodiment, as shown in FIG. 4, the access point 22a updates the shared encryption key K at a predetermined timing. This updating process is also performed autonomously by each access point, that is, without involving other devices. When the new encryption key K 'is distributed, the access point 22a and the terminal 25a regenerate the encrypted data stream using the updated encryption key K'. As described above, if the encryption key K and the encrypted data stream are updated at any time, it is possible to realize highly confidential communication.
[0081]
The embodiment of the wireless communication method according to the present invention has been described above. According to this method, when distributing the encryption key K from the access point 22a or 22b to the terminals 25a, 25b and the wireless bridge 25c, the encryption key K is distributed after being encrypted with the shared secret key Ks in advance. The encryption key K is harder to decipher than when distributed in the state described above. This means that it is difficult to decipher the communication data encrypted with the encryption key K, and highly confidential communication can be realized.
[0082]
Further, in this method, the terminal 25a cannot obtain the encryption key K unless the terminal 25a has previously obtained the same secret key Ks as the access point 22a. If the encryption key K is not shared, the data cannot be decrypted with each other, and thus cannot communicate with each other.
[0083]
In other words, the terminal 25a that has transmitted data that can be decrypted by the access point 22a to the access point 22a is a terminal that holds the same encryption key K as the access point 22a, and holds the same encryption key K. This means that the same secret key Ks is held, and that the same secret key Ks is held means that the access to the terminal to which the administrator has set the secret key Ks in advance, that is, the access point 22a is permitted. Terminal. Therefore, the access point 22a can authenticate the terminal based on whether or not the transmitted data can be decrypted.
[0084]
That is, by thoroughly managing the secret key Ks, unauthorized access by a third party without access authority can be eliminated, and security equivalent to authentication using an IEEE 802.1x RADIUS server can be ensured. .
[0085]
Further, in the present embodiment, as described above, the encryption key is updated as needed. Therefore, even if a third party can obtain an encryption key encrypted with a secret key, the encryption key has already been updated and cannot be used by the time the decryption is successful. Further, as described above, the range of use of the encrypted data stream generated from the encryption key is different for each communication. Therefore, it is more difficult to decipher the communication data as compared with the method of always using the same encryption key, and high confidentiality can be maintained.
[0086]
Further, in the present embodiment, it is significant that the access point once set with the secret key autonomously generates, distributes, and updates the encryption key without depending on other devices. For example, normal processing greatly depends on one computer, such as a method of generating and managing encryption keys collectively in a server, and a method of performing authentication by one RADIUS server such as IEEE 802.1x. In the system, when the server breaks down or an abnormality occurs in a connection path to the server, the function of the wireless LAN portion of the system is completely stopped. On the other hand, in the system of the present embodiment, if a plurality of access points are provided in the system as shown in FIG. 1, even if one access point fails, the terminals 25a and 25b or the wireless bridge 25c The network 19 can be accessed via another access point, and damage due to a failure or the like can be minimized.
[0087]
2. Secret key sharing
Hereinafter, in order to show an embodiment of the key management program of the present invention, the secret key sharing procedure of FIG. 2, that is, the procedure of generating a secret key on the management computer 28 and transferring it to each device will be described in further detail. explain.
[0088]
In the present embodiment, management utility software is installed in the administrator computer 28, and a key management function is provided as one function of this software. As the key management function, there are provided a function of generating a secret key, a function of setting a transfer of a secret key via a cable, and a function of creating an FD for distributing a secret key. The administrator calls each function from a screen menu. Can be executed.
[0089]
FIG. 6 is a diagram for explaining a secret key generation function. First, the key management program uses the administrator password (PW _AD ) Is requested (S101). The administrator 31 sets the administrator password PW. _AD Is input, the key management program randomly generates a secret key Ks (S102). The secret key Ks generated by the key management program is different each time it is generated. Next, the key management program replaces the generated secret key Ks with the administrator password PW input from the administrator 31 in step S101. _AD (S103). Note that in this specification and the drawings, encrypting Y with X is referred to as "E _X (Y) ”, and decoding Y with X is referred to as“ D _X (Y) ". Further, the key management program stores the encrypted secret key Ks in the hard disk 32 of the management computer 28 (S104).
[0090]
Thus, in the present embodiment, the secret key is the administrator password PW _AD Without it, it cannot be created. Further, since the secret key is encrypted and stored in the hard disk, there is no fear that the secret key will be known even if a third party looks at the data in the hard disk.
[0091]
Further, the key management program does not display the generated secret key Ks on the screen at all in the process of steps S101 to S104. Thus, there is no fear that a third party will know the secret key by peeping at the screen during the secret key generation process.
[0092]
FIG. 7 is a diagram for explaining the function of setting the transfer of the secret key via the cable 30 of FIG. In the present embodiment, the administrator computer 28, the access points 22a and 22b, and the wireless bridge 25c hold predetermined common data KM, and use the common data KM for setting a secret key. The common data KM is previously embedded by the manufacturer at the product manufacturing stage. In the case of the access points 22a and 22b and the wireless bridge 25c, the common data KM is stored and held in an internal memory. On the other hand, the administrator's computer 28 is embedded in the program main body of the utility software to be installed on the administrator's computer 28 or definition data used by the program, and is stored in the administrator's computer 28 by installing the software.
[0093]
The transfer of the secret key is performed in order by connecting the access points 22a and 22b to the manager computer 28 one by one. Hereinafter, a case where the administrator computer 28 is connected to the access point 22a by a cable will be described as an example.
[0094]
As shown in FIG. 7, the key management program first reads a MAC address from the access point 22a (S201). Since the MAC address differs for each device, it is described separately from IDi (i = 1, 2, 3,...). Here, the MAC address of the access point 22a is ID1, the MAC address of the access point 22b is ID2, and the MAC address of the wireless bridge 25c is ID5.
[0095]
Next, the key management program encrypts the MAC address ID1 with the common data KM and sets the unique data K unique to the access point 22a. _M1 Is generated (S202). Unique data K generated if the MAC address is different _M1 Is also different, _Mi (I = 1, 2, 3,...).
[0096]
Next, the key management program sends the administrator password PW to the administrator 31. _AD And the password PW entered by the administrator 31 _AD Is received (S203).
[0097]
Correct password PW for administrator from administrator _AD Is input, the key management program reads the encrypted secret key Ks from the hard disk 32 (S204), and enters the input administrator password PW. _AD (S205). Thereby, the key management program reproduces the secret key Ks.
[0098]
The key management program stores the reproduced private key Ks in the individual data K _M1 After that, it is transmitted to the access point 22a via a cable (S207).
[0099]
On the other hand, the access point 22a also encrypts its own MAC address ID1 with the common data KM, and stores the unique data K unique to the access point 22a. _M1 Is generated (S211). Upon receiving the encrypted secret key Ks from the administrator computer 28, the access point 22a converts the encrypted secret key Ks into the generated unique data Ks. _M1 (S212). Further, the access point 22a transmits the decrypted secret key Ks to the unique data K again. _M1 And stored in a storage medium such as an internal flash memory.
[0100]
In the present embodiment, these processes performed by the access point 22a are executed by a program stored in the ROM of the control board constituting the access point 22a.
[0101]
As described above, in addition to the access point 22a, the secret key Ks is set in the access point 22b and the wireless bridge 25c by the same procedure. The secret key transfer setting function is a function for setting a secret key for a device to which a cable can be connected, and the device to be set is an access point or a device with which the access point communicates. It does not matter.
[0102]
FIG. 8 and FIG. 9 are diagrams for explaining the function of creating the private key distribution FD. In the present embodiment, the terminals 25a and 25b also hold the above-described common data KM. The terminals 25a and 25b have wireless communication functions added by inserting the wireless LAN cards 27a and 27b into the notebook personal computers 26a and 26b, respectively, and therefore, driver software for using the wireless LAN cards is incorporated. . The common data KM is embedded in the program body of the driver software or in the definition data used by the program, and is stored in the memories of the notebook computers 26a and 26b by installing the software. However, when the wireless LAN cards 27a and 27b are manufactured, they may be stored in a memory in the wireless LAN card.
[0103]
The creation of the secret key distribution FD is performed in order, such as the FD for the terminal 25a and the FD for the terminal 25b. Hereinafter, the processing of the key management program when creating the FD for the terminal 25a will be described with reference to FIG.
[0104]
The key management program first reads a MAC address from the wireless LAN card 27a (S301). The reading of the MAC address is performed by setting the wireless LAN card on a card reader (not shown) connected as a built-in or external peripheral device to the administrator computer 28. However, if the MAC address of each wireless LAN card is known, the known address may be input to the administrator computer 28 so that the key management program can be referred to. In the following description, the MAC address of the wireless LAN card 27a is ID3, and the MAC address of the wireless LAN card 27b is ID4.
[0105]
The key management program encrypts the MAC address ID3 with the common data KM, and stores the unique data K unique to the wireless LAN card 27a. _M3 Is generated (S302).
[0106]
Next, the key management program sends the administrator password PW to the administrator 31. _AD And the password PW entered by the administrator 31 _AD Is received (S303).
[0107]
Correct password PW for administrator from administrator _AD Is input, the key management program reads the encrypted secret key Ks from the hard disk 32 (S304), and reads the administrator password PW. _AD (S305). Thereby, the key management program reproduces the secret key Ks.
[0108]
The key management program then provides the administrator 31 with the user password PW for each card. _US And an input from the administrator 31 is received (S306). User password PW for each card _US Is a password determined for each user who uses the wireless LAN card. However, for example, when an administrator manages a number of wireless LAN cards collectively, a common user password may be used for all cards.
[0109]
The correct user password PW for each card from the administrator _US Is input, the key management program transfers the reproduced secret key Ks to the card-specific user password PW. _US And then encrypts it with individual data K _M3 (S307), and is recorded on the FD 29a (S308).
[0110]
The key management program similarly reads the MAC address from the wireless LAN card 27b and records the encrypted secret key in the FD 29b.
[0111]
Next, a process of setting the secret key Ks recorded in the FD 29 for the terminal 25a to the terminal 25a will be described with reference to FIG. As described above, the driver software for using the wireless LAN card 27a is incorporated in the notebook personal computer 26a constituting the terminal 25a. The following processing is performed by this driver software or utility software installed together with the driver software.
[0112]
Such a program (software) incorporated in the notebook personal computer 26a executes the following processing when the wireless LAN card 27a is inserted into the notebook personal computer 26a. First, as shown in the figure, the MAC address ID3 of the inserted wireless LAN card 27a is read (S401). However, if the MAC address of the wireless LAN card 27a is known, the user may input the MAC address to the notebook computer 26a in advance. The program encrypts the read MAC address ID3 with the common data KM, thereby obtaining the unique data K unique to the wireless LAN card 27a. _M3 Is generated (S402).
[0113]
Next, the program provides the user 33 (the user 33 and the administrator 31 may be the same) to the user password PW for each card. _US Is requested and the input is received (S403). If the administrator 31 and the user 33 are different, the administrator 31 sets the user password PW for each card. _US Is determined and recorded on paper or the like, and the paper is distributed to the user together with the FD 29. However, if confidentiality can be maintained, the user password PW for each card can be changed by another method. _US May be transmitted.
[0114]
Next, the program reads the double-encrypted secret key from the FD 29a (S404) and generates the unique data K generated in step S402. _M3 And the user password PW for each card input in step S403 _US Then, the secret key Ks is reproduced by decrypting the secret key Ks (S405). The decrypted secret key Ks is again used as the individual data K _M3 And stored in a storage medium such as a hard disk of the notebook personal computer 26a (S406).
[0115]
In the present embodiment, when setting the secret key generated by the administrator computer 28 in an access point or a terminal, the unique data K _M3 Then, the secret key is double-encrypted using the common data KM and then transferred. For this reason, even if the data to be delivered to a third party in the course of cable transfer or FD delivery, it is extremely difficult to reproduce the secret key Ks from the data.
[0116]
In particular, the unique data K _Mj Can be decrypted only by the device corresponding to the unique data, so even if the encrypted private key is handed over to a third party, the device , It is possible to prevent the secret key from being reproduced.
[0117]
When importance is placed on safety, the unique data K _M3 It is preferable to encrypt using both of the secret key and the common data KM. However, even if only one of them is used to encrypt the secret key, appropriate security can be ensured. When encrypting the secret key with only one data, from the viewpoint of security, the unique data K is used as described above. _M3 Is preferable, but if the administrator manages all the terminals or the wireless LAN card collectively, the encryption with only the common data reduces the burden of the secret key management.
[0118]
In the present embodiment, both the access point and the notebook computer are configured to store the secret key in an encrypted state whenever it is stored therein (step S213 in FIG. 7, step S406 in FIG. 9). . That is, the secret key is decrypted and used each time the power of each device is turned on or when the wireless LAN card is inserted into the notebook personal computer. Will not be exposed. Therefore, it is possible to hold and manage the secret key much more securely than the conventional method in which the administrator sets the secret key while looking at the screen.
[0119]
3. Sharing of secret key
Hereinafter, sharing of the encryption key and generation of the encrypted data stream in FIG. 3 will be described in more detail. FIG. 10 and FIG. 11 are diagrams for explaining a detailed procedure of secret key sharing. FIG. 10 shows a procedure from sharing an encryption key to confirming that the encryption key is shared. FIG. 11 is a diagram for explaining a procedure for generating an encrypted data stream. These processes are executed when the power of the access point is turned on. Also, when updating the encryption key after turning on the power, sharing of the encryption key and generation of the encrypted data stream are performed in a similar procedure.
[0120]
The left side of FIG. 10 is a flowchart illustrating processing performed by the access point 22a, and the right side is a flowchart illustrating processing performed by the terminal 25a. As shown in the figure, in the present embodiment, the access point 22a generates random data R that is arbitrary 256-bit data and a challenge code R1 that is arbitrary 64-bit data (S501). Part of the random data R becomes the encryption key K.
[0121]
For the generation of the challenge code R1 and the random data R, for example, a CBC mode used inside the encryption function RC5, a pseudo random code (PN), or the like can be used. Further, as these initial values, values generated by different hardware every time, such as a real-time timer existing in the apparatus, can be used. MAC address information can also be used. Further, the challenge code R1 is preferably set to a different value for each terminal. If the same one is used for a plurality of terminals, the random key R is also the same, so that the secret key Ks is easily decrypted, which is not preferable.
[0122]
The access point 22a transfers the random data R encrypted with the secret key Ks to the terminal 25a following the challenge code R1 (S502). The terminal 25a receives the challenge code R1 and the encrypted random data R (S511), and extracts the random data R by a decryption process using the secret key Ks (S512).
[0123]
Through the above processing, the random data R is shared between the access point 22a and the terminal 25a. The access point 22a and the terminal 25a respectively generate encrypted data streams from the shared random data R (S503, S513).
[0124]
When generating the encrypted data stream, as shown in FIG. 11, the 64 bits from the beginning of the 256-bit random data R are the input data X, the next 64 bits are the initial vector IV, and the remaining 128 bits are the encryption key. Used as K.
[0125]
First, based on the input data X, random data of about 2 Mbytes is generated. Using this 2 Mbytes of data as input to the encryption function, an encrypted data stream is generated using the initial vector IV and the encryption key K. The data of about 2 Mbytes is processed 64 bits at a time. In the figure, block E represents an encryption function. In the present embodiment, an encryption function RC5 is used. A block x represents 64-bit data cut out from the 2 M-byte data.
[0126]
The 64-bit data of the block x is added to the 64-bit initial vector IV to generate 128-bit data. The 128-bit data is encrypted in the block E using the 128-bit encryption key K, and 128-bit encrypted data is generated. At this time, based on the generated data, an initial vector IV ′ used in the next process is generated. By sequentially processing about 2 Mbytes of data generated from the input data X in such a manner of 64 bits, an encrypted data stream having a length of about 2 Mbytes is generated.
[0127]
Returning to FIG. 10, the description will be continued. As described above, in steps S503 and S513, an encrypted data stream is generated, thereby sharing the encrypted data stream. The following is a process for confirming that the encrypted data stream has been shared between the access point 22a and the terminal 25a.
[0128]
In order to confirm that the encrypted data stream has been shared, it is only necessary to transmit and receive a general response signal (ACK / NACK), but in the present embodiment, confirmation is performed according to the following procedure.
[0129]
The terminal 25a encrypts both the 64-bit challenge code R1 received in step S511 and the 256-bit random data R decrypted in step S512 with the secret key Ks (S514). On the other hand, the access point 22a also encrypts both the 64-bit challenge code R1 generated in step S501 and the 256-bit random data R with the secret key Ks (S504).
[0130]
The terminal 25a transmits the data encrypted in step S514 to the access point 22a (S515), and the access point 22a receives the data (S505). In the transfer of steps S502 and S511, the challenge code R1 was not encrypted, but in the transfer of steps S515 and S505, the challenge code R1 is also encrypted.
[0131]
The access point 22a collates the data encrypted in step S504 with the data received from the terminal 25a in step S505 (S506). The access point 22a transmits an authentication success command ACK to the terminal 25a when both match as a result of the collation, and the terminal 25a returns an ACK to the access point 22a as a response (S507, S516). This confirms that the same random data R including the same encryption key K has been shared between the access point 22a and the terminal 25a, and that the encrypted data stream has been shared. In this embodiment, at this time, the access point 22a registers the MAC address ID3 of the wireless LAN card 27a of the confirmed terminal 25a in the internal management table. By this registration, the terminal 25a belongs to the access point 22a.
[0132]
On the other hand, if the result of the comparison in step S506 is that the two do not match, the access point 22a returns an authentication failure command NAK to the terminal 25a, and understands that the terminal 25a has received a NAK from the access point 22a. ACK is returned. At this time, an error message indicating that the authentication has failed is displayed on the screen of the terminal 25a.
[0133]
If the collation results do not match in step S506, the access point 22a and the terminal 25a repeat the processes in steps S501 to S507 and S511 to 516 until the collation results match. However, for example, a predetermined condition may be set such that the process ends if the process does not match even if the process is repeated three times, and the process may be repeated until the condition is satisfied.
[0134]
When sharing of the encrypted data stream is confirmed by the above procedure, it is possible to confirm not only that the encrypted stream is shared but also that the secret key Ks is shared. As described above, the fact that the terminal holds the same secret key Ks as that of the access point 22a means that the terminal is a terminal permitted to communicate with the access point 22a. Therefore, according to the above procedure, terminal authentication can be performed before actual communication starts.
[0135]
In the above, the procedure between the access point 22a and the terminal 25a has been described as an example. However, the access point 22a actually communicates with the terminals 25a, 25b and the wireless bridge 25c as shown in FIG. Processing needs to be performed. As described above, the normal access point and the terminal have a relationship of 1: n (n is an integer of 2 or more).
[0136]
As a procedure for the access point to share the encryption key with n terminals or the like, there are two methods, a method of proceeding simultaneously (in parallel) for all the terminals and a method of sequentially processing the terminals. When processing is performed simultaneously, the access point 22a simultaneously broadcasts the challenge code R1 and the random data R to the terminals 25a, 25b and the wireless bridge 25c, and waits for a response from the terminals 25a, 25b and the wireless bridge 25c. Upon receiving the response, the access point 22a performs the collation processing in step S506 of FIG. 10 in the order in which the replies were received, and registers the ones whose collation results match in the internal management table. On the other hand, in the case of sequentially processing the terminals one by one, the processes of steps S501 to S507 and S511 to 516 in FIG. 10 are sequentially performed for each terminal.
[0137]
Which method is adopted may be determined according to the number of terminals. When the number of terminals is large, it is preferable to perform processing in parallel because the procedure for sharing the encryption key can be completed in a short time, but in terms of processing reliability, it is preferable to perform processing sequentially for each terminal.
[0138]
Here, in the wireless LAN system, the number n of terminals may change at any time. For example, since the terminals 25a and 25b in FIG. 1 are notebook computers, the terminals are not always turned on, and are portable. Therefore, the terminals 25a and 25b are not always within the communication range of the access points 22a and 22b.
[0139]
Therefore, in the present embodiment, the figure is also used when the power of the terminals 25a, 25b or the wireless bridge 25c is turned on and when the terminals 25a, 25b enter the communication range from outside the communication range of each access point 22a, 22b. The processing of Steps S501 to S507 and S511 to 516 is performed. The latter processing is generally called roaming.
[0140]
If the time during which the power is turned off or the time during which the terminal is out of the communication range is extremely short, the terminal may hold the previously distributed encryption key. Since the encryption key is updated at any time, even in such a case, the process for sharing the encryption key is executed again.
[0141]
In this embodiment, since each access point autonomously generates and distributes an encryption key, when changing an access point to be a communication partner, the encryption key is shared again with the changed access point. There must be. If this is manually performed by the user, the burden on the user is not small. However, if the processing of steps S501 to S507 and S511 to 516 in FIG. 10 is automatically executed when the terminal is powered on or when the terminal is moved from outside the communication area to the communication area as described above, the access point Can be changed smoothly.
[0142]
4. Updating the encryption key
As described above, the encryption key is shared when the power of the access point is turned on, when the power of the terminal or the like is turned on, and when the terminal is moved into the communication area. In the present embodiment, the encryption key shared at these timings is used. And the encrypted stream are updated as needed. Hereinafter, the timing of updating the encryption key will be described in detail.
[0143]
Updating of the encryption key K is a process autonomously performed by the access points 22a and 22b, and does not depend on the state of another device. Therefore, the update timing can be freely defined for each access point. Therefore, for example, the timing at which the access point 22a updates the encryption key K and the timing at which the access point 22b updates the encryption key K do not necessarily need to match. Each access point may update the encryption key at all timings described below, or may update the encryption key at some timing selected from the following.
[0144]
As a specific update timing, a method of setting an update interval first and updating periodically may be considered. The update interval may be set to “8 hours”, for example, and may be set to “2 hours” when the risk of eavesdropping increases, depending on the situation. In addition, a method of designating a predetermined time as the update time is also conceivable. When the update time is specified, it is preferable to specify a time at which the number of users of the system is small (for example, 3:00 in the middle of the night) because the degree of influence on the original communication processing can be reduced.
[0145]
Also, a method is conceivable in which the update timing is not defined in advance and the update is appropriately performed according to the situation. For example, if the communication between the access point and the terminal is interrupted for a certain period of time or more, there is a high possibility that communication will not be performed for a while, and a method of performing the update using the time may be considered. Also, the update may be performed when the number of terminals accessing the wired LAN via the access point becomes equal to or less than a predetermined number (for example, when the number of terminals becomes three or less). The “predetermined number” may be determined according to the processing capability of the access point. Also in this case, the degree of influence on the original communication processing can be made relatively small.
[0146]
In addition, it is preferable to provide a function capable of forcibly updating the encryption key by inputting an instruction signal from the outside. This is to enable the encryption key to be changed immediately when unauthorized intrusion into the system is detected.
[0147]
Since the encryption key sharing process is automatically performed when the power of the access point is turned on as described above, the power of the access point may be turned off / on for the purpose of updating the encryption key.
[0148]
As described above, it is preferable to update the encryption key when the degree of influence on the original communication processing is small. However, there are cases where the encryption key update processing must be performed in parallel with the communication processing. Not a few. There are several ways to handle communication processing during encryption key update, as follows.
[0149]
First, a method of updating the encryption key by interrupting the communication process can be considered. For example, in the case of the system of FIG. 1, the access point 22a interrupts the communication process performed between the terminals 25a, 25b and the wireless bridge 25c, and simultaneously performs the communication with the terminals 25a, 25b and the wireless bridge 25c, or After sequentially updating the encryption key according to the procedure shown in FIG. 9, the original communication processing is resumed between the terminals 25a, 25b and the wireless bridge 25c.
[0150]
In this method, the updating process (encrypted data stream sharing) is not disturbed by communication requests from the terminals 25a, 25b and the wireless bridge 25c, so that the encryption key can be updated smoothly in a short time. .
[0151]
Further, a method of updating the encryption key in parallel while performing the original communication processing is also conceivable. In this case, the access point needs to perform communication processing while distinguishing whether or not the encryption key of the communication partner has been updated. For example, in the case of the system of FIG. 1, the access point 22a associates the encryption key with the MAC address of the other party whose encryption key has been shared and indicates whether or not the encryption key of the other party has been updated. Register information. For example, it is registered as 1-bit information of 1 when updated and 0 when not updated. While referring to this information, the access point 22a uses the updated encryption key with the partner whose encryption key has been updated, and uses the encryption key data stream before update with the partner whose encryption key has not been updated yet. Send and receive data.
[0152]
This method is effective when the communication process is not interrupted, it takes time to update all the encryption keys due to a large number of terminals, and there is a problem in interrupting the communication process during that time. . At this time, as described above, if it is possible to quickly determine whether or not the encryption key has been updated based on the bit information, terminals using the encryption key before update and terminals using the encryption key after update may coexist. Even in such a situation, the encryption key updating process can be performed quickly and in parallel with the communication process without lowering the original communication speed.
[0153]
In both the method of interrupting the communication process and the method of updating the encryption key in parallel with the communication process, the access point establishes a wireless communication encrypted with the old encrypted data stream during the encryption key update process. When a packet is received, the wireless packet is discarded, and immediately thereafter, the terminal or the like may be preferentially updated (prior to other terminals or the like) to update the encryption key. In this case, the terminal or the like gives priority to the update processing of the encryption key even when the next wireless packet to be transmitted is accumulated in the transmission buffer.
[0154]
In the present embodiment, TCP / IP is adopted as the communication protocol of the upper layer. However, not only the TCP / IP but also the upper layer protocol generally defines a retransmission procedure when packet transfer is not successful. That is, even if the access point discards the wireless packet, the source of the wireless packet retransmits the same wireless packet after a certain period of time. Therefore, if the encryption key of the terminal or the like is updated before the retransmission is performed, the retransmitted wireless packet is encrypted with the new encryption key and reaches the access point.
[0155]
In this way, when a wireless packet is sent from a terminal or the like that has not been updated, the update processing is immediately performed on the terminal to retransmit the wireless packet encrypted with the new encrypted data stream. By doing so, the processing on the terminal side is not interrupted due to the repetition of the packet retransmission, and the load on the network does not increase.
[0156]
5. Function to reject communication with specific terminals
Further, in the present embodiment, the access points 22a and 22b are configured to prevent the access to the notebook personal computer to which the secret key is set by a valid procedure when the unauthorized personal computer is used by the unauthorized user. Has functions.
[0157]
FIGS. 12A and 12B are diagrams for explaining the function of rejecting communication with a specific terminal. In order to deny access from a specific notebook personal computer (for example, the notebook personal computer 25a) in which a secret key is set, as shown in FIG. The MAC address of the wireless LAN card 27a incorporated in 25a is registered. In other words, each of the access points 22a and 22b manages a communication rejection target registration table 40 in which a MAC address to be rejected for communication is registered. However, the information to be managed may be information other than the MAC address as long as the information can specify the wireless LAN card.
[0158]
FIG. 12B is a flowchart illustrating a process of rejecting communication. The access points 22a and 22b execute this processing at an appropriate timing. For example, the process is executed when the notebook computer 25a issues a request to transfer the encryption key to the access point 22a or 22b. First, in step S601, the access points 22a and 22b acquire the MAC address of the wireless LAN card 27a of the notebook computer 25a to which the transfer of the encryption key has been requested. Next, in step S602, it is determined whether or not the obtained MAC address is registered in the communication rejection target registration table 40. If the acquired MAC address is registered in the communication refusal target registration table 40, a communication refusal notification is transmitted to the notebook computer 25a in step S603. In this case, the encryption key is not transferred. When the acquired MAC address is registered in the communication rejection registration table 40, the normal process described in FIG. 10, that is, the transfer of the encryption key and the sharing confirmation process are executed.
[0159]
The processing shown in FIG. 12B may be executed after the encryption key is transferred. For example, when receiving the communication data encrypted with the encryption key, the access points 22a and 22b execute the processing shown in FIG. 12B, and execute the processing from the target registered in the communication rejection target registration table 40. If it is communication data, it may be discarded. In this case, even when transmitting the communication data, the access points 22a and 22b confirm whether or not the transmission partner is registered in the communication rejection registration table 40, and do not transmit if the transmission partner is registered. To do. The process of FIG. 12B may be executed at the time of the request for the transfer of the encryption key, and the process of FIG. 12B may be executed at the stage of transmitting and receiving the communication data.
[0160]
Also, when the notebook personal computer 25a enters the communication range of the access points 22a and 22b or when the power of the notebook personal computer 25a within the communication range is turned on, the wireless LAN card 27a belongs to the access points 22a and 22b. In the case of a system in which a request is issued, the access points 22a and 22b may execute the processing of FIG. That is, the timing for executing the processing of FIG. 12B is not particularly limited.
[0161]
As described above, in the present embodiment, even if a notebook computer is set with a secret key, if information for identifying the notebook computer is registered in the communication rejection target registration table 40, the access Points 22a and 22b reject communication with the notebook computer. Therefore, even when the notebook computer is lost or stolen, it is possible to prevent unauthorized access by an unauthorized user.
[0162]
6. At the end
The wireless LAN system, the wireless communication method, and the key management program according to one embodiment of the present invention have been described above. In the above description, the access points 22a and 22b correspond to the master wireless communication device of the method of the present invention, and also represent an embodiment of the first wireless communication device of the present invention. Further, the terminals 25a and 25b and the wireless bridge 25c correspond to a slave wireless communication device according to the method of the present invention, and also represent an embodiment of the second wireless communication device of the present invention. The driver software installed in the notebook computers 26a and 26b is an embodiment of the communication control program of the present invention. The recording medium of the present invention is an FD, a CD-ROM, or the like that records the key management program or the communication control program when the program is provided.
[0163]
In the above-described embodiment, as described above, the functions of the terminals 25a and 25b are realized by the driver software of the wireless LAN card. However, the wireless LAN card body may have the same function. Examples of the form in which the main body of the wireless LAN card has functions include a form in which a program is recorded in a memory of a wireless LAN card having a built-in CPU and a memory, and a form in which a circuit for realizing the same function is provided in the wireless LAN card. . Further, a form in which some functions are provided in the wireless LAN card main body and other functions are provided as driver software functions is also conceivable. That is, the function of the slave wireless communication device of the present invention may be realized as software, hardware, or both.
[0164]
Further, the access points 22a and 22b of the above-described embodiment realize the respective functions according to the present invention by the programs operating on the internal control board as described above. However, it is also possible to implement the functions of the present invention as a circuit on a control board, that is, as hardware. That is, the master wireless communication device of the present invention may be realized as software, hardware, or both.
[0165]
In addition, a device in which a wireless LAN card and a control board are incorporated in a housing, and the control board may realize both the function of the access point 22a and the function of the wireless bridge 25c. That is, two types of programs or two types of circuits are mounted on the control board. If a changeover switch is provided so that two functions can be switched, one device can be used as both a master wireless communication device and a slave wireless communication device, and especially for a user who frequently changes the system configuration. convenient. Combinations with other functions, such as an access point and a wireless HUB and an access point and a wireless router, are also conceivable.
[0166]
In the above-described embodiment, RC5 is used as an encryption function in encrypting the secret key Ks and generating an encrypted data stream, but RC4 and NTT developed by RSA are used as encryption functions. A form in which the developed FEAL or DES, AES developed by another company, and other various encryption functions, particularly a common key encryption function may be employed. It goes without saying that not only existing encryption functions but also encryption functions proposed in the future can be applied.
[0167]
【The invention's effect】
In the wireless communication method according to the present invention, an encryption key used for encryption and decryption of communication data transmitted and received between the master wireless communication device and the slave wireless communication device is generated by the master device, and is encrypted with the secret key. To distribute to slave devices. With this method, unless the device holds the same secret key as the master wireless communication device, the encryption key cannot be obtained and the communication cannot be performed. Therefore, it is possible to prevent unauthorized access by a terminal that is not permitted to perform communication. Can be.
[0168]
In addition, since the encryption key is encrypted and transferred by the secret key, it is extremely difficult for a third party to obtain the encryption key by eavesdropping on radio waves and to decrypt the communication content, and the communication content is high. Confidentiality can be maintained.
[Brief description of the drawings]
FIG. 1 is a diagram showing an embodiment of a wireless LAN system according to the present invention.
FIG. 2 is a diagram for explaining a procedure for sharing a secret key.
FIG. 3 is a diagram for explaining a procedure for sharing an encryption key.
FIG. 4 is a diagram showing the entire procedure according to the wireless communication method of the present invention.
FIG. 5 is a diagram for explaining communication data encryption using an encrypted data stream;
FIG. 6 is a diagram for explaining a secret key generation function;
FIG. 7 is a diagram for explaining a secret key transfer setting function;
FIG. 8 is a diagram for explaining a function of creating a private key distribution FD;
FIG. 9 is a view for explaining setting of a secret key using a secret key distribution FD.
FIG. 10 is a diagram for explaining a secret key sharing confirmation process;
FIG. 11 is a diagram for explaining a procedure for generating an encrypted data stream.
FIG. 12 is a diagram for explaining a function of rejecting communication with a specific terminal;
FIG. 13 is a diagram showing a configuration of a general wireless LAN system.
FIG. 14 is a diagram for explaining an authentication and concealment method based on IEEE 802.11;
FIG. 15 is a diagram showing an example of an in-house LAN system in which a wireless LAN is partially introduced.
FIG. 16 is a diagram for explaining an IEEE 802.1x authentication procedure;
[Explanation of symbols]
1 access point, 2 terminal permitted to communicate, 3 notebook computer, 4 wireless LAN card, 5,6 terminal not permitted to communicate, 8 building wall, 9 port, 10 radio wave, 11 communication packet, 12 server, 13 HUB, 14 access point, 15 terminal, 16 wired LAN, 17 authentication server (RADIUS server), 18 registration list, 19 wired LAN, 20 server, 21a, b personal computer group, 22a, b access point, 23a-f personal computer , 24a, b HUB, 25a, b terminal, 25c wireless bridge, 26a, b notebook computer, 27a, b wireless LAN card, 28 management computer, 29 FD, 30 cable, 31 administrator, 32 hard disk, 33 user, 34 Encrypted data stream, 35 Communication packet, 36 encrypted packet, 37 wireless LAN packet, 38 range used for encryption, 39 encrypted data, 40 communication rejection registration table.

Claims (22)

A wireless communication method between a master wireless communication device that functions as an access point for wireless connection to a computer system and at least one slave wireless communication device permitted to communicate with the access point for wireless connection,
The master wireless communication device and the slave wireless communication device share a predetermined secret key,
Generating an encryption key by the master wireless communication device;
The generated encryption key is encrypted using the secret key and transferred from the master wireless communication device to the slave wireless communication device,
On the slave wireless communication device side, by decrypting the transferred encryption key using the secret key, the master wireless communication device and the slave wireless communication device share the encryption key,
A wireless communication method, wherein the shared encryption key is used to encrypt and decrypt communication data transmitted and received between the master wireless communication device and the slave wireless communication device. The wireless communication method according to claim 1, wherein an encrypted data stream generated by encrypting predetermined data using the encryption key is used for encrypting and decrypting the communication data. The wireless communication according to claim 1 or 2, wherein the shared encryption key is updated at the timing by repeating generation, encryption, and transfer of the encryption key by the master wireless communication device at a predetermined timing. Method. When the master wireless communication device is powered on, at a predetermined time, at a predetermined time interval, when communication is interrupted for a predetermined time or more, the number of slave wireless communication devices connected to the master wireless communication device is a predetermined number. 4. The wireless communication method according to claim 3, wherein at least one of the following cases and a time when there is an instruction from the outside. A secret key managed by a predetermined key management device is encrypted using unique data of each of the master wireless communication device and the slave wireless communication device that share the secret key,
Transfer the encrypted secret key to the master wireless communication device and the slave wireless communication device corresponding to each unique data,
The encrypted and transferred secret key is decrypted by using the unique data of the wireless communication device in the master wireless communication device or the slave wireless communication device on the transfer side, respectively.
The wireless communication method according to any one of claims 1 to 4, wherein the secret key is shared by the master wireless communication device and the slave wireless communication device. After encrypting the secret key managed by the predetermined key management device using the unique data of each of the master wireless communication device and the slave wireless communication device sharing the secret key and / or the second password, Stored in the storage medium of
In each of the corresponding master wireless communication device and slave wireless communication device, the encrypted secret key read from the storage medium is decrypted using the unique data of the wireless communication device and / or the second password. By
The wireless communication method according to claim 1, wherein the secret key is shared by the master wireless communication device and the slave wireless communication device. The slave wireless communication device, the encryption key decrypted using the secret key, after encrypting again using the secret key, transferred to the master wireless communication device,
The master wireless communication device checks the encryption key encrypted by the master wireless communication device itself using the secret key, with the encryption key encrypted and transferred by the slave wireless communication device. The wireless communication method according to claim 1. A wireless communication device that functions as an access point for wireless connection to a computer system,
Secret key holding means for holding a predetermined secret key;
Encryption key generation means for generating an encryption key used for encryption and decryption of communication data,
Key encryption means for encrypting the encryption key generated by the encryption key generation means using the secret key held by the secret key holding means;
Transfer means for transferring the encryption key encrypted by the key encryption means to another wireless communication device holding the same secret key as the secret key,
A wireless communication device for transmitting and receiving communication data encrypted and decrypted using the encryption key to and from the another wireless communication device. 9. The data transmission / reception unit according to claim 8, wherein an encrypted data stream generated by encrypting predetermined data using the encryption key is used for encrypting and decrypting the communication data. Wireless communication device. Repeating the generation of the encryption key by the encryption key generation unit, the encryption by the key encryption unit, and the transfer by the transfer unit at a predetermined timing, thereby updating the shared encryption key at the timing. The wireless communication device according to claim 8 or 9, wherein The timing of the update, when power is turned on, a predetermined time, a predetermined time interval, when communication is interrupted for a predetermined time or more, when the number of slave wireless communication devices connected to the master wireless communication device becomes a predetermined number or less, 11. The wireless communication apparatus according to claim 10, wherein the time is at least one of an instruction from the outside and an instruction from the outside. The wireless communication device encrypts again the encryption key using the secret key, and the other wireless communication device decrypts the encryption key using the secret key using the secret key. The wireless communication device according to claim 8, further comprising a matching unit configured to check an encrypted encryption key returned to the communication device. Among other wireless communication devices holding the same secret key as the secret key, communication rejection target storage means for storing a wireless communication device whose access permission to the computer system has been canceled as a communication rejection target,
9. The communication rejection unit that rejects execution of a process required for transmitting and receiving the communication data with the wireless communication device stored as a communication rejection target by the communication rejection target storage unit. The wireless communication device according to any one of claims 12 to 12. A wireless communication device that performs wireless communication with an access point for wireless connection to a computer system,
Secret key holding means for holding a predetermined secret key;
Key decryption in which the wireless connection access point encrypts using the same secret key as the secret key and decrypts the encryption key transferred to the wireless communication device using the secret key held by the secret key holding means Means,
A wireless communication device for transmitting and receiving communication data encrypted with the wireless connection access point using the encryption key decrypted by the key decryption device. . A communication control program that controls a communication function of a slave wireless communication device that performs wireless communication with a master wireless communication device that functions as an access point for wireless connection to a computer system, wherein the slave wireless communication device includes:
Secret key holding means for holding a predetermined secret key;
Key decryption in which the master wireless communication device encrypts using the same secret key as the secret key and decrypts the encryption key transferred to the slave wireless communication device using the secret key held by the secret key holding means. Means,
A communication control program for functioning as data transmission / reception means for transmitting / receiving communication data encrypted with the master wireless communication device using the encryption key decrypted by the key decryption means. 16. The data transmission / reception unit according to claim 15, wherein an encrypted data stream generated by encrypting predetermined data using the encryption key is used for encrypting and decrypting the communication data. Communication control program. A computer-readable recording medium on which the communication control program according to claim 15 is recorded. A communication control device that controls a communication function of a slave wireless communication device that performs wireless communication with a master wireless communication device that functions as an access point for wireless connection to a computer system,
Secret key holding means for holding a predetermined secret key;
Key decryption in which the master wireless communication device encrypts using the same secret key as the secret key and decrypts the encryption key transferred to the slave wireless communication device using the secret key held by the secret key holding means. Means,
A communication control device, comprising: a data transmission / reception unit for transmitting / receiving communication data encrypted with the master wireless communication device using an encryption key decrypted by the key decryption unit. A common secret key is set for both wireless communication devices of a master wireless communication device that functions as an access point for wireless connection to a computer system and a slave wireless communication device that is permitted to communicate with the access point for wireless connection. Key management program for performing
A device-specific encryption function for encrypting a predetermined secret key using unique data of each wireless communication device for setting the secret key,
A key management program for realizing a secret key transfer function of transferring a secret key encrypted by the device-specific encryption function to each wireless communication device corresponding to unique data used for encryption. A key management program for setting a common secret key for a master wireless communication device functioning as an access point for wireless connection to a computer system and a slave wireless communication device permitted to communicate with the access point for wireless connection And on the computer,
A device-specific encryption function for encrypting a predetermined secret key using unique data and / or a second password of each wireless communication device for setting the secret key;
A key management program for realizing an external output function of storing a secret key encrypted by the device-specific encryption function in a predetermined storage medium. A computer-readable recording medium on which the key management program according to claim 19 or 20 is recorded. In a wireless LAN system including a master wireless communication device functioning as a wireless connection access point to a computer system and at least one slave wireless communication device permitted to communicate with the wireless connection access point,
The master wireless communication device,
Master-side secret key holding means for holding a predetermined secret key;
Encryption key generation means for generating an encryption key used for encryption and decryption of communication data,
Key encryption means for encrypting the encryption key generated by the encryption key generation means using the secret key held by the secret key holding means;
Transfer means for transferring the encryption key encrypted by the key encryption means to the slave wireless communication device holding the same secret key as the secret key;
Master-side data transmitting and receiving means for transmitting and receiving communication data encrypted using the encryption key, with the slave wireless communication device,
The slave wireless communication device,
Slave-side secret key holding means for holding the predetermined secret key,
Key decryption means for decrypting the encryption key transferred from the transfer means of the master wireless communication device using a secret key held by the slave side secret key holding means,
A wireless LAN system comprising: a slave-side data transmitting / receiving unit for transmitting / receiving communication data encrypted with the master wireless communication device using an encryption key decrypted by the key decryption unit. .

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