JP5239123B2 - Wireless LAN system - Google Patents

Description

  The present invention particularly relates to a wireless LAN system, a wireless access point, a wireless terminal device, and a network identifier notification method for a wireless access point.

Normally, in a wireless LAN system, a wireless terminal device is connected to an access point (hereinafter abbreviated as AP). In a system based on IEEE802.11, first, the wireless terminal device searches for an AP that is a probe request signal of SSID: ANY. Send a signal and create a list of nearby APs. Then, select the AP you want to connect from the list of APs and connect.
Here, the SSID refers to an identifier of an AP in an IEEE 802.11 series wireless LAN that is a group of wireless LAN standards. Because wireless LAN uses radio waves to communicate, unlike wired LAN, there is a possibility of "interference" that allows communication with multiple APs. Set SSIDs for wireless LAN APs and each wireless terminal. Thus, communication can be performed only with a terminal having the same SSID. The probe request signal of SSID: ANY is a signal for requesting connection using a special SSID “ANY” that can be connected to any AP. When the wireless terminal transmits the AP search signal, the AP that can communicate with the wireless terminal notifies the SSID set in the AP. Therefore, communication between the wireless terminal and the AP can be established using the notified SSID.

  However, in the connection method to the AP as described above, since the SSID of the AP is known from any wireless terminal in the effective radio wave range of the AP, a third party wireless terminal can communicate with the AP. There was a problem in communication security. Therefore, in consideration of security, APs in stealth mode, which has the function of rejecting connections from wireless terminals with SSID “ANY”, have appeared.

To connect to this stealth mode AP, set the SSID of the stealth mode AP in the wireless terminal device or set the setting information in the wireless terminal device within the effective range of the stealth mode AP. It is necessary to move to the coverage area of the mode AP. However, since the stealth mode AP does not respond to the AP search signal, there is a problem that it is very difficult to find the radio wave coverage of the AP when the location of the stealth mode AP is unknown. For such problems, for example, inventions such as Patent Document 1 and Patent Document 2 have been proposed.
JP 2004-343448 A JP 2005-184314 A

  However, as a security issue, the frame in the wireless communication packet is not encrypted, so if you monitor the packet of the exchange between the legitimate wireless terminal device and the AP in stealth mode using capture software etc., stealth mode There was still a problem that there was a vulnerability to be able to see the SSID of APs.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a wireless LAN system, a wireless access point, a wireless terminal device, and a network identifier notification method for a wireless access point that solve the above problems. And

In order to solve the above problems, the present invention has the following configuration.
The gist of the invention described in claim 1 is a wireless terminal device;
Receiving an access point search signal transmitted from the wireless terminal device, referring to a database in which the MAC address of the wireless terminal device is stored, and sending a network identifier notification signal to the wireless terminal device registered in the database A wireless access point for transmitting
The network identifier notification signal exists in a wireless LAN system in which a network identifier storage area is encrypted.
The gist of the invention described in claim 2 is that the encryption is encryption of a common key cryptosystem using a common key stored in the database and the wireless terminal device. Exist in the wireless LAN system.
The gist of the invention of claim 3 is that the network identifier notification signal includes an encryption determination area in which the wireless terminal device determines that the network identifier notification signal is encrypted, and an encrypted network identifier. The wireless LAN system according to claim 1, wherein the wireless LAN system includes a stored network identifier storage area.
The gist of the invention described in claim 4 is that the determination method for encryption of the network identifier storage area is determined to be encrypted if it is 0x00 with reference to the first byte of the network identifier notification signal. The present invention resides in the wireless LAN system according to claim 3.
The gist of the invention described in claim 5 is that an access point search signal transmitted from a wireless terminal device is received,
A wireless access point that refers to a database in which the wireless terminal device is registered and transmits a network identifier notification signal to the wireless terminal device registered in the database,
The network identifier notification signal exists in a wireless access point characterized in that a network identifier storage area is encrypted.
The gist of the invention described in claim 6 is that the encryption is encryption of a common key method using a common key stored in the database and the wireless terminal device. Located in a wireless access point.
The gist of the invention described in claim 7 is that the network identifier notification signal includes an encryption determination area in which the wireless terminal device determines that the network identifier notification signal is encrypted, and an encrypted network identifier. 7. The wireless access point according to claim 5 or 6, wherein the wireless access point comprises a stored network identifier storage area.
The gist of the invention described in claim 8 is that the network identifier storage area encryption determination method refers to the first byte of the network identifier notification signal and determines that it is encrypted if it is 0x00. It exists in the wireless access point of Claim 7 characterized by these.
The gist of the invention described in claim 9 is a wireless terminal device that transmits an access point search signal and receives a network identifier notification signal from a wireless access point,
The wireless terminal device is characterized in that the network identifier included in the network identifier notification signal is encrypted, and comprises a decrypting means for decrypting the encrypted network identifier.
The gist of the invention of claim 10 is that the encryption is encryption of a common key cryptosystem using a database referenced by the wireless access point and a common key stored in the decryption means. The present invention resides in a wireless terminal device according to claim 9.
The gist of the invention described in claim 11 is that the network identifier notification signal includes an encryption determination area in which the wireless terminal device determines that the network identifier notification signal is encrypted, and the encrypted network identifier. The wireless terminal device according to claim 9 or 10, wherein the wireless terminal device is configured with a network identifier storage area in which is stored.
The gist of the invention described in claim 12 is that the network identifier storage area encryption determination method refers to the first byte of the network identifier notification signal and determines that it is encrypted if it is 0x00. The radio terminal apparatus according to claim 11, wherein:
The gist of the invention of claim 13 is a network identifier notification method of a wireless access point that transmits a network identifier notification signal in response to an access point search signal from a wireless terminal device,
A matching step in which a wireless access point refers to a database and matches a registered wireless terminal device;
An encryption step of encrypting a network identifier with a common key stored in the database corresponding to the wireless terminal device;
A wireless access point comprising: an encrypted network identifier transmitting step of adding an encryption determination area to an encrypted network identifier and transmitting the network identifier notification signal to the registered wireless terminal device Network identifier notification method.
The gist of the invention of claim 14 is characterized in that the encryption is encryption of a common key cryptosystem using a database referenced by the wireless access point and a common key stored in the wireless terminal device. The present invention resides in a network identifier notification method for a wireless access point according to claim 13.
The gist of the invention described in claim 15 resides in a network identifier notification method for a wireless access point according to claim 13 or 14, characterized by comprising a decoding step of decoding the network identifier notification signal.
The gist of the invention of claim 16 is characterized in that it has a network identifier storage area encryption judgment step of judging that it is encrypted if it is 0x00 with reference to the first byte of the network identifier notification signal. The present invention resides in a network identifier notification method for a wireless access point according to any one of claims 13 to 15.
The gist of the invention described in claim 17 resides in a program capable of executing the network identifier notification method for a wireless access point according to any one of claims 13 to 16.

  In the wireless LAN system of the present invention, a stealth mode AP can be searched and found using an AP search signal in the same manner as a normal AP from a wireless terminal registered in the database. Since the network identifier in the wireless communication packet transmitted from the AP is encrypted, the third party wireless terminal other than the legitimate wireless terminal is monitored by using capture software or the like. I can't know. Therefore, there is a remarkable effect that the security of wireless communication can be enhanced.

<First Embodiment>
A first embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a configuration diagram of a wireless LAN system according to the present embodiment. The wireless LAN system of the present embodiment includes a wireless access point 101 (hereinafter abbreviated as AP 101), a database 103 connected to the AP 101 and accessible by the AP 101, and a wireless terminal device 102. Here, the AP 101 and the database 103 may be connected through a network such as the Internet or a dedicated line, or the database 103 may be directly provided in the AP 101 as a storage medium. In addition, the wireless terminal device 102 includes a decryption unit that decrypts an encrypted network identifier notification signal, which will be described later. This decryption means may be installed in the wireless terminal apparatus 102 as a program. In addition, the “network identifier” here indicates, for example, the above-mentioned SSID in the system compliant with IEEE802.11 of the present embodiment, but this network identifier is not limited to the SSID, and communication An identifier other than the SSID may be used as long as it is an identifier that identifies the other party and has the property that communication cannot be performed if the identifiers do not match each other.

  The AP 101 has the above-described stealth mode function and a function of notifying a specific wireless terminal apparatus 102 of an SSID. In addition, it has a function of encrypting and transmitting the SSID of the AP 101 when notifying the wireless terminal apparatus 102 of the SSID.

  Further, the wireless terminal device 102 has a wireless communication function and a function of transmitting an AP search signal. A function for determining whether the SSID is encrypted with respect to the response signal from the AP 101 is provided. When the SSID is encrypted, a function for decrypting using the decryption unit 105 is provided. The response signal here refers to a probe response signal from the AP 101.

  Further, the DB 103 stores registration information of the wireless terminal device 102 that permits notification of the SSID of the AP 101 and a key necessary for encryption corresponding to the wireless terminal device 102 in association with each other. The registration information and the key necessary for encryption will be described in detail later.

  Next, the operation of the wireless LAN system of this embodiment will be described with reference to FIG. First, the AP 101 connects to the DB 103 that stores the MAC address of the wireless terminal device that permits SSID notification. The MAC address is an ID number unique to the Ethernet (registered trademark) card mounted on the LAN device. Here, the registration information of the wireless terminal device 102 registered in the database is not limited to this MAC address, and it is ID information that can uniquely identify the wireless terminal device 102 to which the AP 101 permits connection. Anything can be used. The AP 101 in the stealth mode notifies the AP search signal from the wireless terminal apparatus 102 registered in the DB 103 by encrypting the SSID. As a result, the wireless terminal device 102 registered in the DB 103 can search for and find the stealth mode AP 101 using the AP search signal in the same manner as a normal AP.

  The DB 103 stores the MAC address of the wireless terminal device 102 and information that is a key for encrypting the SSID of the AP 101 in association with the wireless terminal device 102. The key information for encrypting the SSID is preferably a common key of a common key cryptosystem from the viewpoint of encryption strength, but it is information that can securely encrypt and decrypt the SSID. If it exists, it may be a key of another encryption method. When the AP 101 notifies the wireless terminal apparatus 102 of the SSID, the encryption is performed using the common key 104 stored in the DB 103, so that the third party wireless terminal apparatus 102 not registered in the database 103 SSID interception can be prevented. This SSID common key 104 is a common key that encrypts and decrypts the SSID storage area, which is a 32-byte character string, using a common key encryption method, and holds different SSID common keys for each wireless terminal device 102. The common key of the AP 101 is stored in the database 103 in association with the terminal device 102.

  Next, the configuration of the AP 101 will be described in detail with reference to FIG. First, the AP 101 includes a transmission / reception unit 201, a MAC address extraction unit 202, a DB communication unit 203, an SSID encryption unit 204, and a control unit 205. The transmission / reception unit 201 has a function of receiving an AP search signal from the wireless terminal device 102 and transmitting a response signal to the wireless terminal device 102 that permits SSID notification. The MAC address extraction unit 202 has a function of extracting and temporarily storing the MAC address of the transmission source wireless terminal device 102 in the AP search signal from the wireless terminal device 102. Further, the DB communication unit 203 has a function of searching whether or not the MAC address of the wireless terminal device 102 extracted by the MAC address extracting unit 202 exists in the DB 103 and notifying the search result. In the search result, when the MAC address exists in the DB 103, the DB 103 also has a function of extracting the SSID common key 104 corresponding to the wireless terminal device 102 having the MAC address. The SSID encryption unit 204 has a function of encrypting the SSID to be notified using the SSID common key 104 extracted from the DB 103 and storing the encrypted SSID in the SSID storage area. The SSID storage area here is an area for storing a 32-byte SSID defined in IEEE 802.11, and is one of control data transmitted and received during connection processing between the AP 101 and the wireless terminal apparatus 102. Point to. The control unit 205 has a function of controlling each of the above functions. Each of these components is configured by hardware such as a microprocessor, a memory, a storage medium, and the like, and a program mounted thereon.

  Next, the configuration of the wireless terminal apparatus 102 will be described in detail with reference to FIG. First, the wireless terminal apparatus 102 includes a transmission / reception unit 301, an SSID common key storage unit 302, an SSID storage area extraction unit 303, an encrypted SSID determination unit 304, an SSID decryption unit 305, and a control unit 306. The transmission / reception unit 301 has a function of transmitting an AP search signal and receiving a response signal from the AP 101. The SSID common key storage unit 302 has a function of holding the SSID common key 104 unique to the wireless terminal apparatus 102. The SSID storage area extraction unit 303 has a function of extracting the SSID storage area from the response signal from the AP 101 and temporarily storing it. The encrypted SSID determination unit 304 has a function of extracting an SSID storage area from the response signal from the AP 101 and determining whether or not the SSID is encrypted. The SSID decryption unit 305 has a function of decrypting the encrypted SSID using the SSID common key stored in the SSID common key storage unit 302. The control unit 306 has a function of controlling each function described above. Each of these components is configured by hardware such as a microprocessor, a memory, a storage medium, and the like, and a program mounted thereon.

  Next, details of the operation flow of the wireless LAN system of this embodiment will be described with reference to FIGS. As a precondition, it is assumed that the DB 103 stores the MAC address of the wireless terminal device 102 and the SSID common key 104 held by the wireless terminal device 102. First, the wireless terminal device 102 broadcasts an AP search signal. Here, “transmitting by broadcast” refers to transmitting data to a large number of unspecified parties in the network. Then, the AP 101 receives the AP search signal and extracts the source MAC address from the AP search signal. Then, the AP 101 searches whether or not the extracted MAC address exists in the DB 103, and if it exists, the SSID common encryption key 104 corresponding to the MAC address is extracted from the database 103. Then, the AP 101 encrypts the SSID notified to the wireless terminal device 102 registered in the database 103 with the SSID common key 104 and stores it in the SSID storage area of the response signal. Then, the AP 101 transmits a response signal to the wireless terminal apparatus 102 by unicast. Here, “transmit by unicast” means to transmit data to a specific partner by designating a single address in the network. Here, the wireless terminal apparatus 102 that has been registered by referring to the database 103 Is to identify and send data to it. The wireless terminal apparatus 102 receives the response signal and extracts the SSID storage area from this response signal. When the wireless terminal device 102 determines that the extracted SSID storage area is encrypted, the wireless terminal device 102 decrypts it using the SSID common key 104 stored in the wireless terminal device 102 and acquires the SSID. Thereafter, wireless communication is started with the AP 101 using the acquired SSID.

  Further, detailed operations from when the AP search signal of the AP 101 is received until the response signal is transmitted will be described with reference to FIGS. First, in the AP 101, the transmission / reception unit 201 receives an AP search signal from the wireless terminal device 102 (S501). Next, from the received AP search signal, the MAC address extraction unit 202 extracts the MAC address of the wireless terminal device 102 as the transmission source (S502). Next, the DB communication unit 203 checks whether the extracted MAC address exists in the DB 103. Whether or not is searched (collation step). If the extracted MAC address exists in the DB 103, the process proceeds to SSID common key acquisition from the database 103 (S504), and if the extracted MAC address does not exist in the DB 103, the process ends. When the process proceeds to the acquisition of the SSID common key from the database 103, the SSID common key 104 corresponding to the MAC address extracted from the AP search signal by the DB communication unit 203 is extracted from the DB 103 (S504). Next, the SSID encryption unit 204 encrypts the SSID notified to the wireless terminal apparatus 102 with the SSID common key 104 extracted from the DB 103 (encryption step), and stores it as an encrypted SSID in the SSID storage area of the response signal (S505). ). The transmitting / receiving unit 201 transmits the response signal to the wireless terminal apparatus 102 by unicast (S506, encrypted SSID transmission step).

Detailed operations from the reception of the response signal of the wireless terminal apparatus 102 to the extraction and decoding of the SSID will be described with reference to FIGS. First, in the wireless terminal device 102, the transmission / reception unit 301 receives a response signal from the AP 101 (S601). Next, the SSID storage area extraction unit 303 extracts the SSID storage area from the received response signal (S602). Next, the encrypted SSID determination unit 304 determines whether the character string in the extracted SSID storage area is encrypted (S603). If the character string is encrypted, the encrypted SSID determination part 304 decrypts the SSID storage area (S604). If not, the character string in the SSID storage area will end with no SSID. The determination of whether or not the data is encrypted will be described in detail later. When the process proceeds to decryption of the SSID storage area, the SSID decryption unit 305 decrypts the encrypted SSID storage area using the key 104 stored in the SSID common key storage unit 302, and converts the SSID of the AP 101 into Obtain (S604, decoding step).

Next, a notification method when the SSID storage area is encrypted and a method for determining whether or not the SSID storage area is encrypted will be described in detail with reference to FIGS.
In the normal unencrypted SSID storage area, as shown in FIG. 8, the SSID character string is stored from the beginning of the 32-byte SSID storage area, and the end of the character string is determined by 0x00 at the end.
Therefore, as a notification method when the SSID storage area is encrypted, 0x00 is stored in the first 1 byte of the 32-byte SSID storage area as shown in FIG. After that, the encrypted SSID is stored in 31 bytes.
The method for determining whether or not the SSID storage area is encrypted is that if the first 1 byte is seen and 0x00, it is determined that it is encrypted, and the subsequent 31 bytes are decrypted using the SSID common key 104. If the first byte is other than 0x00, it is determined as non-encrypted, and the SSID is extracted as it is (SSID storage area encryption determination step).

<Second Embodiment>
Next, a second embodiment of the present invention will be described. The configurations of the AP 101, the wireless terminal device 102, and the database 103 are the same as those in the first embodiment. The SSID storage area encryption method is also the same as in the first embodiment. This embodiment is different from the first embodiment in that the common encryption key 104 provided to the AP 101 and the wireless terminal device 102 is not a unique key for each wireless terminal device 102, but a common key. Accordingly, the AP 101 encrypts and notifies the SSID with the SSID common key 104 for the AP search signals from all the wireless terminal apparatuses 102. When the wireless terminal apparatus 102 that has received this notification holds the SSID common key 104, the acquired SSID storage area can be decrypted, but the wireless terminal apparatus 102 that does not hold the SSID common key 104 acquires the acquired SSID storage area. Configured to destroy. By adopting such a configuration, in this embodiment, since it is not necessary to store a common key for each wireless terminal device 102, a remarkable effect that the amount of data held in the database 103 can be reduced is achieved. Play.

  Note that the wireless LAN system, the wireless access point, the wireless terminal device, and the SSID notification method of the wireless access point of the present invention are not limited to the above embodiments, and are within the technical scope that can be conceived by those skilled in the art. Improvements, modifications, and changes can be made as appropriate.

  In the wireless LAN system of the present invention, the wireless terminal device registered in the DB can search and find the stealth mode AP using the AP search signal in the same way as a normal AP. Setting at the start is facilitated, and user convenience can be greatly improved. In addition, since the SSID is encrypted when the SSID is notified, the SSID can be prevented from being intercepted, and the security in the steless mode is improved, which can greatly contribute to maintaining the security of the user's network.

  Also, in the wireless LAN system of the present invention, the portion to be encrypted is only the SSID storage area, and the wireless communication frame is not changed, so it is easy to implement and widely and easily introduced into the currently operating wireless LAN system. Is possible. As for the ease of introduction to the currently operating wireless LAN system, in the present invention, the wireless terminal device having no function (application) for determining the encryption of the SSID storage area acquires the encrypted SSID storage area. In this case, since the first 1 byte of the encrypted SSID storage area is 0x00 as shown in FIG. 9, the wireless terminal device having no function to determine encryption recognizes the first 0x00 as a termination character, so nothing is stored in the SSID storage area. Recognize that it is not. For this reason, even if a wireless terminal device that does not have a function (application) for determining the encryption of the SSID storage area acquires an encrypted SSID storage area, it does not cause a malfunction, so the introduction of the present invention into the existing system is easy. It is mentioned that.

Configuration diagram of a wireless LAN system according to an embodiment of the present invention Operation explanatory diagram of the wireless LAN system in the embodiment of the present invention Configuration diagram of a wireless access point in an embodiment of the present invention Configuration diagram of a wireless terminal device in an embodiment of the present invention Operation flow chart of wireless LAN system in the embodiment of the present invention Operation flowchart of wireless LAN access point in embodiment of the present invention Operational flow chart of wireless terminal device in embodiment of the present invention Illustration of SSID notification signal sent from a normal wireless LAN access point Explanatory drawing of the SSID notification signal in the embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Wireless access point 102 Wireless terminal device 103 Database 104 Common encryption key 105 Decryption means 201 Transmission / reception part (wireless access point)
202 MAC address extraction unit (wireless access point)
203 Database communication unit (wireless access point)
204 SSID encryption unit (wireless access point)
205 Control unit (wireless access point)
301 Transmission / reception unit (wireless terminal device)
302 SSID common encryption key storage (wireless terminal equipment)
303 SSID storage area extraction unit (wireless terminal device)
304 Encrypted SSID determination unit (wireless terminal device)
305 SSID decoding unit (wireless terminal equipment)
306 Control unit (wireless terminal device)

Claims (13)

A wireless terminal device;
An access point search signal transmitted from the wireless terminal device, including an access point search signal including the MAC address of the transmission source wireless terminal device, and uniquely identifying the wireless terminal device with respect to the wireless terminal device permitting connection If identified by referring to the MAC address and the wireless terminal database unit and different common keys for each are registered in association, MAC address included in the access point search signal received is registered in the database in, and a radio access point to transmit a network identifier notification signal to the radio terminal corresponding to the MAC address registered in the database,
The network identifier notification signal is a common key that is different for each wireless terminal device stored in the database and the wireless terminal device, and from the database as a common key corresponding to a MAC address included in the access point search signal. A wireless LAN system, wherein a network identifier storage area is encrypted by a common key encryption method using an extracted common key .   The network identifier notification signal includes an encryption determination area in which the wireless terminal device determines that the network identifier notification signal is encrypted, and a network identifier storage area in which the encrypted network identifier is stored. The wireless LAN system according to claim 1.   The method according to claim 2, wherein the network identifier storage area encryption determination method refers to the first 1 byte of the network identifier notification signal and determines that the network identifier is encrypted if it is 0x00. Wireless LAN system. An access point search signal transmitted from a wireless terminal device, and receiving an access point search signal including the MAC address of the wireless terminal device of the transmission source ,
Refers to database said that the wireless terminal device that uniquely identifies the MAC address and the wireless terminal device different common key for each registered in association with a wireless terminal device which permits the connection, the access point searches received A wireless access point that transmits a network identifier notification signal to the wireless terminal device corresponding to the MAC address registered in the database when the MAC address included in the signal is registered in the database;
The network identifier notification signal is a common key that is different for each wireless terminal device stored in the database and the wireless terminal device, and from the database as a common key corresponding to a MAC address included in the access point search signal. A wireless access point, wherein a network identifier storage area is encrypted by a common key encryption method using an extracted common key .   The network identifier notification signal includes an encryption determination area in which the wireless terminal device determines that the network identifier notification signal is encrypted, and a network identifier storage area in which the encrypted network identifier is stored. The wireless access point according to claim 4.   6. The method according to claim 5, wherein the network identifier storage area encryption determination method refers to the first byte of the network identifier notification signal and determines 0x00 if encrypted. Wireless access point. Means for transmitting an access point search signal including the MAC address of its own device as a transmission source ;
Refers to database said that the wireless terminal device that uniquely identifies the MAC address and the wireless terminal device different common key for each registered in association with a wireless terminal device which permits the connection, the access point searches received When a MAC address included in a signal is registered in the database, a wireless access point that transmits a network identifier notification signal to the wireless terminal device corresponding to the MAC address registered in the database from the network A wireless terminal device having means for receiving an identifier notification signal,
The network identifier included in the network identifier notification signal is encrypted, and comprises decryption means for decrypting the encrypted network identifier;
The encryption is a common key corresponding to a MAC address included in the access point search signal, which is a different common key for each of the wireless terminal devices stored in the database referred to by the wireless access point and the decryption means. A wireless terminal device characterized by encryption of a common key cryptosystem using a common key extracted from the database .   The network identifier notification signal includes an encryption determination area in which the wireless terminal device determines that the network identifier notification signal is encrypted, and a network identifier storage area in which the encrypted network identifier is stored. The wireless terminal device according to claim 7, wherein   9. The method of determining encryption of the network identifier storage area, wherein the first identifier byte of the network identifier notification signal is referred to and 0x00 is determined as being encrypted. Wireless terminal device. A network identifier notification method for a wireless access point that transmits a network identifier notification signal to an access point search signal that is transmitted from a wireless terminal device and includes the MAC address of the wireless terminal device that is the transmission source There,
Wireless access point, with reference to the database that the is a wireless terminal device that uniquely identifies the MAC address and the wireless terminal device different common key for each registered in association with a wireless terminal device which permits the connection, receiving When a MAC address included in the access point search signal is registered in the database, a verification step of verifying a wireless terminal device corresponding to the registered MAC address;
An encryption step of encrypting a network identifier with a common key stored in the database corresponding to the wireless terminal device;
An encrypted network identifier transmitting step of adding an encryption determination area to the encrypted network identifier and transmitting the network identifier notification signal to the registered wireless terminal device,
The encryption is a common key that is different for each wireless terminal device stored in the wireless terminal device and a database referenced by the wireless access point, and is a common key corresponding to the MAC address included in the access point search signal A network identifier notification method for a wireless access point, characterized in that the encryption is based on a common key cryptosystem using a common key extracted from the database .   The method of claim 10, further comprising a decoding step of decoding the network identifier notification signal.   12. The network identifier storage area encryption determination step for determining that the network identifier storage area is encrypted if it is 0x00 with reference to the first byte of the network identifier notification signal. Network identifier notification method for wireless access points   The program which can perform the network identifier notification method of the wireless access point in any one of Claims 10 thru | or 12.