JPH07162954A - Unauthorized use preventing method for mobile communication terminal - Google Patents

Abstract

PURPOSE:To prevent unauthorized use caused by the forgery of terminal identification information in a mobile communication terminal to be charged corresponding to the utilizing amount of a portable telephone or the like. CONSTITUTION:A mobile communication terminal 1 and a radio exchange 2 hold authentication keys 11 stored at the several times of radio line connection in the past and the mobile communication terminal is authorized by detecting whether these authentication keys are matched or not by a comparator 23. Each time of connection, the oldest part of the authentication key is abrogated and the new part is generated by an authentication key generator 26 inside the radio exchange so as to prevent the interception of the authentication key or the unauthorized use caused by the internal analysis of the terminal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing unauthorized use in a mobile communication terminal which is charged according to the usage amount of a mobile phone or the like.

[0002]

2. Description of the Related Art A mobile communication terminal (hereinafter referred to as a mobile station), such as a mobile phone, is used to identify each mobile station.
A different manufacturing number is given to each mobile station. At the time of communication, in addition to the subscriber number, the manufacturing number is transmitted to the wireless switching center (hereinafter, switching center), and the switching center collates the preregistered subscriber number with the manufacturing number. It is designed to check the legitimacy of the mobile station you are trying to connect to.

The manufacturing number and the subscriber number are fixed for each mobile station, and once registered, they will not be changed thereafter. Also, these numbers are
Since it is transmitted from the mobile station to the exchange, it is possible for a third party to intercept this transmission and there is a risk that the combination of these numbers will be known. If the combination of numbers is known, it becomes possible for a third party to pretend to be a legitimate user and call, and as a result, an unauthorized charge may be made to the legitimate user. There is a nature.

In order to prevent such unauthorized use, the invention disclosed in, for example, Japanese Patent Application Laid-Open No. 61-29294 has been conventionally made. However, the conventional invention has the following drawbacks.

[0005]

According to the method for preventing unauthorized use according to the prior art, a third party who intercepts the manufacturing number and the subscriber number can be detected without being detected by the authorized user or the exchange. Unauthorized use cannot continue. But,
This method cannot detect the first unauthorized use. For this reason, a third party cannot use the same manufacturing number and subscriber number in succession, but each time an illegal use is performed, another manufacturing number and subscriber number are intercepted and a new authorized user is newly added. You can pretend to make a call. This abuse is also not detected.

[0006] Another conventional method for preventing unauthorized use is a method of performing verification by an exchange using not only static data but also dynamic data. For example, there is a method of storing the number of times of connection between the mobile station and the exchange, and collating this information at the time of connection. In such a method, illegal use can be more effectively prevented by making the method of generating dynamic data complicated.
However, no matter how complicated the dynamic data generation method is, if the dynamic data generation method is known, it is easily illegally used. A fraudulent user can pretend to be a legitimate user by intercepting other legitimate users' calls, waiting for the end of the current call, and then sending the expected dynamic data, and not being detected. . In order to obtain a dynamic data generation method, for example, an internal analysis of a communication terminal by an unauthorized user having sufficient technology can be considered. As described above, a sufficient unauthorized use preventing effect cannot be expected for an unauthorized user having advanced technology.

The problem with the conventional system is that the communication terminal itself determines based on the information transmitted from the exchange, the current time, the number of times the communication terminal is used, and other data that can be uniquely determined by interception of communication. The point is that the authentication data is generated based on the single algorithm that is held, and this is sent back to the exchange. That is, it is theoretically possible to impersonate another communication terminal by sufficiently analyzing the inside of the communication terminal. One of the methods to eliminate this problem is to prepare a considerable number of programs and data to be incorporated inside when providing a communication terminal to a user, and allocate them appropriately to each communication terminal. There is a method such as. However, this method is a very inefficient method in terms of the number of types of communication terminals from the viewpoint of manufacturing and maintenance of communication terminals. Considering that the communication terminal is widely used, it is desirable that the communication terminal itself is as uniform as possible.

An object of the present invention is to provide an unauthorized use prevention system which is effective for an unauthorized user having the above-mentioned advanced technology without increasing the number of types of communication terminals.

[0009]

The above object is to provide a mobile communication terminal which identifies a registered user by an authentication operation with respect to a wireless switching center and charges a fee according to the usage amount.
The authentication keys exchanged between the wireless switching center and the mobile communication terminal by wireless communication in the past are stored independently by the wireless switching center and the mobile communication terminal, and the authentication operation for the mobile communication terminal is stored independently. It is solved by using both authentication keys.

[0010]

When the mobile station requests a connection to the exchange, the authentication key held by the mobile station is first transmitted to the exchange. The exchange station compares the sent authentication key with the authentication key held by the exchange station, and if they match, permits the connection with the mobile station.

In order to prevent the authentication key from being stolen, the authentication operation is performed by encrypting the authentication key when wirelessly transmitting the authentication key and decrypting the decryption means when receiving the authentication key. Further, by providing a means for updating the authentication key each time the mobile station and the exchange are connected, it becomes more difficult to steal the authentication key.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a conventional example using the conventional technique will be described. As shown in FIG. 7, the mobile station 1 includes a control device 31, a counter 32, a table 33, and a transmitter 34, and the exchange station 2 includes a control device 41, a counter group 42, a table group 43, and a receiver. And 44.

The counter 32 of the mobile station counts the normal connection of the mobile station to the exchange station, and operates, for example, to increase the value by 1 every connection. The switching center has counters 4 as many as the number of mobile stations it controls.
2, and normally counts the normal connection of each mobile station to the exchange.

As shown in FIG. 8, the table 33 of the mobile station.
Is the subscriber number 101 registered in the mobile station,
It holds the identification information code 111. The switching center holds as many subscriber numbers 201 to 203 and identification information codes 211 to 213 as the number of mobile stations in the table group 43.

The value indicated by the counter in the mobile communication station x and the value indicated by the counter x corresponding to the mobile communication station x in the exchange are usually the same. If these values do not match each other at the time of connection processing, the exchange considers this as a connection due to unauthorized use and takes measures such as rejecting the connection.

This check is performed in the following procedure. A counter value, a subscriber number, and an identification information code are transmitted from the mobile station. Upon receipt of this, the exchange performs match detection of the respective data, and when these match, the connection is permitted. The counter value always changes with each connection, and the identification information code is transmitted from the mobile station only and not from the exchange station, which has the effect of preventing unauthorized use.

However, as described above, if the unauthorized user succeeds in the internal analysis of the mobile communication terminal, there is no effect. Further, if an unauthorized user intercepts a call from a legitimate user, there is a risk that all the counter value, subscriber number, and identification information code at that time will be known.

An embodiment of the present invention for solving these problems will be described below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, FIG.
[Fig. 7] is an operation explanatory view of the embodiment of the present invention. The configuration and operation of this embodiment will be described below. In FIG.
Reference numeral 1 is a mobile station such as a mobile phone, and 2 is a wireless exchange station that controls circuit switching of the mobile phone. The mobile station 1 includes an authentication key queue 11, an encryptor 12, a decryptor 13, a transmitter 14, and a receiver 15. The exchange 2 also includes an authentication key queue 21, an encryption device 22, a decryption comparator 23, and a transmitter 2.
4, a receiver 25, and an authentication key generator 26. Further, in FIG. 2, reference numeral 71 denotes an operation flow of the mobile station,
Reference numerals 72 show the operation flow of the exchange.

The mobile station authentication key queue 11 has the first authentication key 5
It is composed of an array of 8 authentication keys of 1 to 8 authentication keys 58, and different authentication key data can be stored in each area of the array. Exchange authentication key queue 21
Like the mobile station authentication key queue 11, the first authentication key 61
To 8th authentication key 68, and is composed of an array of 8 authentication keys. In this embodiment, each authentication key data area can store an integer of 64 bits.

The encryption device 12 is for not being intercepted by a third party when transmitting the authentication key data in the wireless section. In the present embodiment, the encryptor 12 is an integer multiplier, which multiplies all eight 64-bit integer authentication keys and outputs a 512-bit integer operation result.

The data obtained by the encryptor 12 is sent to the transmitter 1.
4 to the exchange 2. The exchange is the receiver 25
The encrypted data is obtained through the above, and the decryption comparator 23 performs decryption and coincidence detection using the authentication key data held by the exchange side. In the present embodiment, the decryption comparator 23 is an integer divider, which sequentially divides the 512-bit integer sent from the mobile station by each of the first to eighth authentication keys, and at the end of the calculation, the quotient is 1 and the remainder is 0. When it becomes, it is considered that the authentication keys match, and a match detection signal is output.

If the same data is always used as the authentication key, the data may be stolen due to interception of communication. This is because if a legitimate user always uses the same authentication key, the third party need only intercept the communication and send the same authentication key. Therefore, in this embodiment, the confidentiality of the authentication key is maintained by newly generating and updating a part of the authentication key data each time a call connection is made. The procedure related to this update will be described below.

When the mobile station 1 and the exchange 2 are connected according to the above procedure, the authentication key generator 26 generates one new authentication key. It is desirable to use an appropriate random number sequence to generate the authentication key. Subsequently, the oldest eighth authentication key among the eight authentication keys held by the exchange is discarded,
As a result, the data of the second oldest seventh authentication key is transferred to the vacant eighth authentication key area 68. Similarly, the remaining data is also sequentially transferred, and the previously generated new authentication key is transferred to the first authentication key area 61 that is finally empty.

Next, it is necessary to transmit the new authentication key generated here to the mobile station. Otherwise, only the authentication key of the exchange will be updated, and the authentication operation will not be possible at the next connection. This transmission is performed by the following procedure.

First, on the side of the mobile station, the oldest eighth authentication key data among the eight authentication keys held by the mobile station is discarded, and the second oldest authentication key area 58 is left in the empty eighth authentication key area 58. 7 Authentication key data is transferred. Similarly, the remaining data is sequentially transferred, and the last first authentication key area 51 is left empty. Then, on the exchange side, the first authentication key 61 and the second authentication key 62, which are the two newest data in the exchange authentication key queue 21 reconfigured by the above-mentioned procedure, are set to the encryption device 22. Use to encrypt. In this embodiment, two pieces of authentication key data are multiplied to obtain a 128-bit integer result. This data is transmitted to the decoder 13 on the mobile station side via the transmitter 24 and the receiver 15. Decoder 13
Uses the newest second authentication key 52 of the seven authentication keys held by the mobile station to decrypt the encryption. In this embodiment, the given 128-bit integer is divided by the second authentication key, and the data remaining as the quotient is replaced with the new first authentication key 51.
Save as. Even if the encrypted authentication key is intercepted by a third party, the authentication key cannot be easily decrypted. Each authentication key is a decimal number of about 20 digits, and the encrypted data is a multiplication value of at least two of these authentication keys. Therefore, in order to decrypt each authentication key from the encrypted data, factorization is required. There is a need to do. However, with the currently known factorization method, it takes a lot of time to factor such a large numerical value, so that deciphering is practically impossible. By such a procedure, the authentication key is secretly updated every time a call is connected.

By the way, using the above procedure, the authentication key may be stolen if the communication for updating the authentication key is continuously intercepted several times. This point will be described with reference to FIG. According to this embodiment, the authentication data 81 transmitted from the mobile station and the authentication key update data 82 transmitted from the exchange are the data shown in the figure.

For example, in the initial state, it is assumed that 64-bit integers A to H are stored in the data areas of the first to eighth authentication keys. The encrypted data transmitted by the mobile station for authentication is the product of the eight latest authentication keys. Therefore, the authentication data transmitted from the mobile station during the first call is the product of A to H, that is, (A ×
B × C × D × E × F × G × H). Also, the product of the eighth authentication key and the newly generated authentication key is transmitted from the exchange. Assuming that the new authentication key is I, the authentication key update data transmitted from the exchange at the first call is (H × I) as shown in the figure. After that, the old authentication key data is discarded one after another each time the connection is made, and the call is continued while replacing with the new data.

Data sent from the mobile station for authentication during the eighth call is from H to O as shown in the figure.
(H × I × J × K × L × M × N × O). However, this data is a part of the four pieces of authentication transmission data from the exchanges in the past, that is, the first, third, fifth
It is easily obtained by multiplying the transmission data of the seventh call. Since the above-mentioned transmission data are (H × I), (J × K), (L × M), and (N × O), these multiplication results are (H × I × J × K × L × M).
× N × O), which is exactly the same as the authentication data by the authorized user. Therefore, the third party intercepts the most recent 7 calls, to be exact, the newest one, the 1st, 3rd, 5th, and 7th all 4 calls, and the authentication sent from the exchange at the time of those calls. By multiplying all product values of keys,
The product of the authentication keys can be obtained. By using this data, a third party can make a call pretending to be an authorized user.

In order to steal such an authentication key, it is necessary to continuously intercept the calls of the same authorized user. Therefore, it is difficult but not impossible to carry out the call.

Next, FIG. 4 is a configuration diagram of another embodiment of the present invention for solving such a problem, and FIG. 5 is an operation explanatory diagram of another embodiment. The symbols in FIGS. 4 and 5 have the same meanings as the symbols in FIGS. 1 and 2, respectively.

As described above, the first embodiment is incomplete as a method for preventing unauthorized use by a third party. The difference of this embodiment from the above-mentioned first embodiment is only the difference in the combination of the data input to the encoder and the decryptor of both the mobile station 1 and the exchange 2. In the first embodiment,
The encrypted data transmitted from the mobile station to the exchange has been generated by multiplying all eight authentication keys held by the mobile station. On the other hand, in the present embodiment, the sixth authentication key is not subject to encryption by the mobile station and is not transmitted from the mobile station, and therefore is not subject to decryption or comparison even on the exchange side. Further, the encrypted data transmitted from the exchange to the mobile station is transmitted by multiplying the first authentication key and the second authentication key in the first embodiment. On the other hand, in the present embodiment, the first authentication key and the sixth authentication key are multiplied and transmitted.

Next, the operation of this embodiment will be described.

The mobile station authentication key queue 11 and the exchange station authentication key queue 21 have the same configurations as those of the first embodiment, and each authentication key data area can store an integer of 64 bits.

The encryptor 12 is an integer multiplier in this embodiment, and it multiplies 7 out of 8 64-bit integer authentication keys excluding the 6th authentication key and outputs a 448-bit integer operation result. .

The data obtained by the encryptor 12 is sent to the transmitter 1
4 to the exchange 2. The exchange is the receiver 25
The previous encrypted data is obtained via the, and the decryption comparator 23 performs decryption and match detection. In this embodiment, the decoding comparator 2
3 is an integer divider, 448 sent from the mobile station
Bit integers are sequentially divided by 7 authentication keys excluding the 6th authentication key out of the 8 authentication keys held by the exchange side, and the quotient becomes 1 and the remainder becomes 0 at the end of the calculation. In case,
It is considered that the authentication keys match, and a match detection signal is output.

When the mobile station 1 and the exchange 2 are connected by such a procedure, the authentication key generator 26 generates one new authentication key. Further, the oldest eighth authentication key among the eight authentication keys held by the exchange is discarded, and the data of the second oldest seventh authentication key is transferred to the empty eighth authentication key area 68 by this. It Similarly, the remaining data is also sequentially transferred, and the previously generated new authentication key is transferred to the first authentication key area 61 that is finally empty.

Next, it is necessary to transmit this new authentication key to the mobile station. This transmission is performed by the following procedure.

First, on the side of the mobile station, the oldest eighth authentication key data among the eight authentication keys held by the mobile station is discarded, and the second oldest authentication key area 58 is thus vacated. 7 Authentication key data is transferred. Similarly, the remaining data is sequentially transferred, and the last first authentication key area 51 is left empty. Then, on the exchange side, the first authentication key 61 and the sixth authentication key 66 generated previously in the exchange authentication key queue 21 reconfigured by the above procedure are transferred to the encryption device 22.
To encrypt. In this embodiment, as in the previous example, two pieces of authentication key data are multiplied to obtain a 128-bit integer result. This data is transmitted by the transmitter 24 and the receiver 1.
5 to the decoder 13 on the mobile station side. The decryptor 13 uses the sixth authentication key 56 out of the seven authentication keys held by the mobile station to decrypt the cipher. In this embodiment, the given 128-bit integer is divided by the sixth authentication key, and the data remaining as the quotient is stored as a new first authentication key 51.

By using the encrypted data generated in this way, even if a third party intercepts the call of the authorized user completely continuously, the authentication key data is not easily stolen. You can This will be described with reference to FIG. According to this embodiment, the authentication data 83 transmitted from the mobile station and the authentication key update data 84 transmitted from the exchange are the data shown in FIG.

When such data is transmitted, the correct authentication data can be easily known even if a third party intercepts all of the first to seventh calls and the calls before that. There is no fear. The data including the authentication key transmitted at the time of a call is a multiplication value of at least two authentication keys, and since each transmission data is irregularly generated as compared with the first embodiment, it is easy to It cannot be deciphered.

[0042]

According to the present invention, in order for an illegal user to impersonate a specific authorized user, it is necessary to at least continuously listen to the telephone call of the user, so that the illegal use is extremely difficult. It is difficult, and as a result, there is an effect that illegal use can be eliminated.

Further, since the authentication key is sequentially updated with the call of the authorized user, continuous unauthorized use by the unauthorized user can be eliminated.

Even if the mobile communication terminal is analyzed by an unauthorized user, the authentication key generation pattern may be unknowingly known because the authentication key required for connection is generated at the exchange. It is a safe method to prevent unauthorized use.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an authentication operation according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of authentication communication data according to the embodiment of this invention.

FIG. 4 is a configuration diagram of another embodiment of the present invention.

FIG. 5 is an explanatory diagram of an authentication operation according to another embodiment of the present invention.

FIG. 6 is an explanatory diagram of authentication communication data according to another embodiment of the present invention.

FIG. 7 is a configuration diagram of a conventional example.

FIG. 8 is a configuration diagram of a conventional authentication data table.

[Explanation of symbols]

1 ... Mobile station, 2 ... Exchange station, 11 ... Mobile station authentication key queue,
12 ... Mobile station encoder, 13 ... Mobile station decoder, 14 ... Mobile station transmitter, 15 ... Mobile station receiver, 21 ... Exchange station authentication key queue, 22 ... Exchange station encoder, 23 ... Exchange station decoder, 24
... exchange station transmitter, 25 ... exchange station receiver, 26 ... authentication key generator, 31 ... mobile station controller, 32 ... mobile station counter,
33 ... Mobile station table, 34 ... Mobile station transmitter, 41 ... Switching station control device, 42 ... Switching station counter group, 43 ... Switching station table group, 44 ... Switching station receiver, 51 ... Mobile station first authentication key, 52 ... Mobile station second authentication key, 53 ... Mobile station third authentication key, 54 ... Mobile station fourth authentication key, 55 ... Mobile station fifth authentication key, 56 ... Mobile station sixth authentication key, 57 ... Mobile station first 7 authentication key, 58 ... Mobile station eighth authentication key, 61 ... Exchange station first authentication key, 62 ... Exchange station second authentication key, 63 ... Exchange station third authentication key, 64 ... Exchange station fourth authentication key, 65 ... exchange station fifth authentication key, 66 ... exchange station sixth authentication key, 67 ... exchange station seventh authentication key, 68 ... exchange station eighth authentication key, 71 ... mobile station authentication operation flow, 72 ... exchange station authentication operation flow , 73 ... Another mobile station authentication operation flow, 74 ... Another switching center authentication operation flow, 8
1 ... Mobile station authentication transmission data, 82 ... Exchange station authentication key update transmission data, 83 ... Other mobile station authentication transmission data, 8
4 ... Another exchange station authentication key update transmission data, 101 ... Mobile station subscriber number data, 111 ... Mobile station identification information code,
201 ... Exchanger subscriber number data 1, 202 ... Exchanger subscriber number data 2, 203 ... Exchanger subscriber number data 3, 211 ... Exchanger identification information code 1, 212 ... Exchanger identification information code 2, 213 ... Switching center identification information code 3.

Claims (6)

[Claims] 1. A mobile communication terminal for identifying a registered user by an authentication operation for a wireless switching center and charging a fee according to the usage amount, wherein between a wireless switching center and a mobile communication terminal by wireless communication in the past. The mobile communication terminal and the mobile communication terminal store the authentication keys exchanged in 1. above independently, and the authentication operation for the mobile communication terminal is performed using both of the authentication keys stored independently. How to prevent unauthorized use of communication terminals. 2. The operation of exchanging the authentication key by the wireless communication,
The method for preventing unauthorized use of a mobile communication terminal according to claim 1, wherein the method is performed every time a connection operation between the mobile communication terminal and the wireless switching center is performed. 3. The operation of exchanging an authentication key by the wireless communication,
The method for preventing unauthorized use of a mobile communication terminal according to claim 1, wherein the method is performed at least once during communication between the mobile communication terminal and the wireless switching center. 4. The operation of exchanging an authentication key by the wireless communication,
4. The method for preventing unauthorized use of a mobile communication terminal according to claim 2, wherein the method is performed by exchanging only a part of the authentication key stored in the mobile communication terminal or the wireless switching center. 5. The wireless switching center and the mobile communication terminal store an authentication key exchanged by at least two authentication key exchange operations in the past, and the authentication operation stores all or a part of the stored authentication keys. The method for preventing unauthorized use of a mobile communication terminal according to claim 2, 3 or 4, wherein the method is performed by using the mobile communication terminal. 6. The authentication key exchanging operation between the wireless exchange and the mobile communication terminal by the wireless communication is performed after encryption using the past authentication key as a key. Item 6. A method for preventing unauthorized use of a mobile communication terminal according to item 2, 3, 4 or 5.