WO2009117949A1

WO2009117949A1 - A method for enhancing network communication security and a wireless accessing apparatus

Info

Publication number: WO2009117949A1
Application number: PCT/CN2009/070986
Authority: WO
Inventors: 刘绍峰; 郭江; 郇海滨; 陈颖浩; 翁武林
Original assignee: 华为技术有限公司
Priority date: 2008-03-24
Filing date: 2009-03-24
Publication date: 2009-10-01
Also published as: CN101277528A; CN101277528B

Abstract

A method for enhancing network communication security is provided, and the said network is a global system for mobile communication GSM network, the method includes the following steps: during the communication process between the network side and the mobile terminal, the network side transmits the channel switching information to the mobile terminal according to the pre-configured security tactics, the security tactics includes that the channel switching information is transmitted to the terminal at definite time or indefinite time; the mobile terminal performs the channel switching according to the channel switching information, and continues the communication in the switched channel. A wireless accessing apparatus is also provided in the present invention. When the present invention is used, the communication channel of the mobile terminal in the GSM network can not be fixed in a certain physical channel, thus the illegal network intruder can not aim at the certain channel to collect the information, the efficiency of the attacking is lowered distinctly, thus the security of the air interface is enhanced.

Description

Method for enhancing network communication security and wireless access device The application is submitted to the Chinese Patent Office on March 24, 2008, and the application number is 200810026974.1, and the invention name is "a method for enhancing network communication security and wireless connection." The priority of the Chinese patent application is incorporated herein by reference. Technical field

The present invention relates to the field of wireless communications, and in particular, to a method for enhancing network communication security and a wireless access device. Background technique

At present, most of the encryption algorithms in the Global System for Mobile Communications (GSM) air interface are A51 algorithms. The algorithm's cracking algorithm now has two main categories:

a. Plaintext attack. This attack mode requires the attacker to intercept the required data frames, and know the contents of these frames before decryption, and then use the ciphertext comparison composed of the data before and after encryption to crack. If the law of the downlink protocol message is relatively fixed, the possibility of the illegal network intruder guessing success will be great, and the communication key (Kc) will be cracked with a high probability, which will seriously affect the session security. .

b. ciphertext attack. In this attack mode, even if the illegal network intruder does not guess the content of the message, the relationship between the redundancy check code and the message content when the air interface signaling message is encoded may be used to establish a system of equations, and Continuously collect signaling to eliminate the element. If an illegal network intruder collects sufficient signaling messages, it can initiate a ciphertext attack and also crack the session Kc with a high probability.

In the process of call setup, the GSM system generally allocates a Stand-alone Dedicated Control Channel (SDCCH), and allocates a Traffic Channel (TCH) through a channel assignment command on the SDCCH channel. Therefore, if an illegal network intruder successfully tracks a call of a certain user, it will consider first completing the crack on the SDCCH, and acquiring the information of the TCH channel allocated for the user on the SDCCH, thereby tracking the specific TCH channel, and acquiring User's call information.

The encryption command in the GSM system is sent in clear text, and the encryption command encrypts the wireless connection. After the encryption command is sent, the air interface signaling sent after the encryption command is transmitted in cipher text, and the signaling sequence of the transmission usually has certain characteristics. For example, for the calling party, the first downlink signaling after the encryption is completed is likely to be Call Proceeding; for the called party, the first uplink message is likely to be Call Confirmed, and the content of the message is easy to guess. In this way, the attacker may use these messages to conduct plaintext attacks and obtain the cracked plaintext.

On the TCH channel, according to the protocol, the network side periodically sends system messages to the mobile phone on the SACCH channel accompanied by the TCH, including: system message 5, system message 5bis, system message 5ter, system message 6. These messages may be exploited by illegal network intruders to initiate plaintext attacks. For example, system message 5, system message 5bis, system message 5ter, because the message content is relatively fixed, illegal network intruders are more likely to guess. In addition, since these messages are sent periodically on a relatively fixed channel, the illegal network intruder can initiate a ciphertext attack, and even if the plaintext is not guessed, sufficient system message data can be collected on a fixed channel within a certain period of time. Frame, using the relationship between the redundancy check code and the message content when A5 encrypts the pre-encryption signaling, establishes a system of equations, and solves the key by solving the equation.

In the creation process of the present invention, the inventors have found that in the above background art, since the user signaling interaction after the encryption is completed is still performed on the original channel, and the content of the partial message is easy to guess after the encryption is completed, and the central processing unit (Central Processing Unit, CPU) / Field Programmable Gate Array (FPGA) has more and more powerful processing power and lower price, which makes the cost of illegal network hackers launching ciphertext attacks lower and lower. Crack GSM A51 The algorithm has become more beneficial, which seriously affects the security of the GSM air interface. Although the A53 encryption algorithm updated in GSM can improve the security of GSM, a large number of mobile phones and devices on the Internet do not support the A53 algorithm due to hardware and software limitations. Therefore, the operators of GSM are required to adopt no change. Under the premise of the A51 algorithm and the existing mobile terminal, the security of GSM is improved. Summary of the invention

The technical problem to be solved by the present invention is to provide a method and wireless access device for enhancing network communication security. It can improve the communication security of the hollow port of the GSM network.

In order to solve the above technical problem, in one aspect, an embodiment of the present invention provides a method for enhancing network communication security, the network is a global mobile communication system GSM network, and the method includes: communicating with a mobile terminal at a network side The network side sends channel switching information to the mobile terminal according to a preset security policy, where the security policy includes: sending the channel to the terminal periodically or irregularly. Switching information; the mobile terminal performs channel switching according to the channel switching information, and continues the communication on the switched channel. .

In another aspect, an embodiment of the present invention provides a wireless access device, including: an acquiring unit, configured to acquire channel switching information and a security policy, where the channel switching information is used to indicate that a corresponding mobile terminal performs channel switching, where The security policy includes: sending the channel switching information to the mobile terminal by sending the channel switch timing to the terminal periodically or irregularly.

The technical solution provided by the embodiment of the present invention can make the signaling information of the mobile terminal in the GSM network not be fixedly transmitted on a certain physical channel, so that the illegal network intruder cannot collect information for a specific channel, and the efficiency of launching the attack will be Greatly reduced, so the safety of the air interface can be enhanced. DRAWINGS

1 is a schematic flow chart of a specific embodiment of a method for enhancing network communication security in the present invention;

2 is a schematic diagram of a specific embodiment of channel occupancy of channel switching in a cell in the present invention;

3 is a schematic diagram showing the composition of a specific embodiment of a network access device in the present invention. detailed description

Embodiments of the present invention are described below with reference to the accompanying drawings. Referring to FIG. 1 , it is a schematic flowchart of a specific embodiment of a method for enhancing network communication security according to the present invention. The method includes:

The network side sends channel switching information to the mobile terminal according to a preset security policy, where the security policy includes: sending the channel switching information to the terminal periodically or irregularly. The network is a GSM network.

In an embodiment of the present invention, the security policy may include: sending the channel switching information to the terminal according to the time parameter, where the time parameter is used to indicate that the network side sends the channel switching information to the mobile terminal periodically or irregularly. Moment. For example, the time parameter may include the number of times the channel switching information is sent in one session, the interval time or the specific time, and the like. In the embodiment of the present invention, the number of times is not limited, and may be only one time or multiple times. , As the case may be. The above-mentioned sending time can be specified through the list - or it can be generated according to certain rules, such as random production according to a certain probability distribution. Health.

The channel switching information may include a channel assignment command, a channel switching command, or other commands, and the channel switching parameter is included in the foregoing command. The mobile terminal can parse out these parameters in the command and perform channel switching based on these parameters. The information of the current session is generally assigned by the channel assignment command during session initialization, and in the subsequent process, when channel switching is required, the channel switching command is used to specify which channel to switch to for the session.

The channel assignment command, channel switching command or other command may include specific channel switching parameters in each channel switching, or may include channel switching parameters corresponding to multiple channel switching. The channel switching parameter may include one of a Mobile Allocation Index Offset (MAIO), a Hopping Sequence Number (HSN), and a Training Sequence Code (TSC) parameter. A variety.

In an embodiment of the invention, channel switching information is transmitted to the mobile terminal, and one or more of the above parameters determined according to the security policy may be included in the channel switching information. Thus, at different times in the same session, the communication signaling and voice of the wireless network and the mobile terminal will be transmitted on different channels or even different frequency points, as shown in FIG. In FIG. 2, the same vertical square represents the occupancy of different channels in the same period of time, the same horizontal square represents the occupation of different time segments of the same channel, and the thin slash square represents different occupations occupied by different time periods in the session A. Channels, black squares represent different channels occupied by different time periods in Session B.

The range of values of the above three parameters can be referred to as follows:

MAIO: Mobile allocation index offset (0 to N 1, 6 bits).

HSN: Hopping sequence (generator) number (0 to 63, 6 bits).

TSC: Training Sequence Code ( 0 to 7, 3bits).

Since the sending of these parameters is sent through the encrypted signaling, if the illegal network intruder does not know these parameters, it cannot know which channel the next encrypted signaling will be sent at the next moment, and the attack cannot be launched. . In a cell, the possible combinations of these parameters are 8 (TSC) * 64 (HSN) * 3 (MAI0) * 8 (channel) = 12288, so illegal network intruders are not likely to know by guessing parameters. On which channel the signaling will be sent at a time.

On the other hand, since the signaling and voice of the mobile terminal are transmitted on different channels (such as a dedicated control channel and a traffic channel), even if the illegal network intruder cracks the key of the mobile terminal in this session by guessing the plaintext, The above parameters of the mobile terminal are still not known. As each The signaling or voice of each mobile terminal on the physical channel is not continuously transmitted, or it is not distinguishable which signaling belongs to the mobile terminal. Therefore, other signaling of the mobile terminal cannot be cracked, and effective monitoring cannot be initiated.

102. The mobile terminal performs channel switching according to channel switching information received by the mobile terminal, and continues the communication on the switched channel. That is, as shown in FIG. 2, the mobile terminal can perform channel switching multiple times during one session, and transmit signaling or data on the switched channel.

At the same time, it should be noted that in one session, the network side can be transmitted multiple times (specific number and transmission time, on which channel, etc. can be determined by the security policy). The channel switching information is sent periodically or irregularly, so as shown in FIG. 1 The process shown in the process is an iterative process.

Correspondingly, an embodiment of the present invention further provides a network side device that can notify a mobile terminal to perform channel switching periodically or irregularly, and the device may be a wireless access device in a GSM network, such as a base station. As shown in FIG. 3, it is a schematic diagram of a composition of a wireless access device in an embodiment of the present invention. The device includes: an obtaining unit 12, configured to acquire channel switching information and a security policy, where the channel switching information is used to indicate that the corresponding mobile terminal performs channel switching, where the security policy includes: sending the channel to the terminal periodically or irregularly The switching unit 14 is configured to be used according to the obtained terminal during a call of the mobile terminal.

The obtaining unit 12 includes a time parameter obtaining subunit, and a time parameter obtaining subunit, configured to obtain a policy for setting a time parameter in the security policy, where the time parameter is used to indicate that the acquiring unit 12 is sent. The method may further include one or more of the following subunits: a first acquiring subunit, configured to acquire a mobile allocation pointer offset parameter in the channel switching information, and a second obtaining subunit, configured to acquire frequency hopping in the channel switching information a sequence number parameter; a third acquisition subunit, configured to acquire a training sequence number parameter in the channel switching information.

The definition and interpretation of the above information, policies, and parameters in this embodiment are consistent with those in the foregoing methods. In the embodiment of the present invention, the channel for communication between the mobile terminal and the network side is not fixed, so that the illegal network intruder cannot collect information for a specific physical channel, and the efficiency of launching the attack is greatly reduced, so that the security of the air interface can be enhanced. The embodiment provided in the present invention is effective for a GSM communication network employing an encryption algorithm in A5's encryption algorithm set (e.g., A51, A52, and A53, etc.).

The above is only the embodiment of the present invention, and of course, the right to the present invention cannot be limited thereby. The scope of the invention is therefore within the scope of the invention.

Claims

Rights request

A method for enhancing network communication security, the network being a global mobile communication system GSM network, wherein the method comprises:

In the process of the network side communicating with the mobile terminal, the network side sends the channel switching information to the mobile terminal according to the preset security policy, where the security policy includes: sending the channel switching information to the terminal periodically or irregularly;

The mobile terminal performs channel switching according to the channel switching information, and continues the communication on the switched channel.

2. The method according to claim 1, wherein the transmitting the channel switching information to the terminal periodically or irregularly comprises:

Transmitting, by the time parameter, the channel switching information to the terminal, where the time parameter is used to refer to

3. The method of claim 2, wherein the channel switching information comprises a channel assignment command or a channel switch command.

The method according to claim 3, wherein the channel assignment command or the channel handover command includes a channel handover parameter, and the channel handover parameter includes a mobile allocation pointer offset, a frequency hopping sequence number, and a training sequence. One or more of the number parameters.

The method of any of claims 1 to 4, wherein the channel comprises a dedicated control channel or/and a traffic channel.

A wireless access device, the device comprising:

An acquiring unit, configured to acquire channel switching information and a security policy, where the channel switching information is used to indicate that the corresponding mobile terminal performs channel switching, where the security policy includes: sending the channel switching information to the terminal periodically or irregularly;

a sending unit, configured to acquire a security policy according to the acquiring unit during a call of the mobile terminal The channel switching information is sent to the mobile terminal periodically or irregularly.

The device according to claim 6, wherein the acquiring unit comprises: a time parameter obtaining subunit, configured to acquire a policy for setting a time parameter in the security policy, and a time at which the information is switched.

The device according to claim 6 or 7, wherein the obtaining unit further comprises one or more of the following subunits:

a first acquiring subunit, configured to acquire a mobile allocation pointer offset parameter in the channel switching information, and a second acquiring subunit, configured to acquire a frequency hopping sequence number parameter in the channel switching information;

And a third acquiring subunit, configured to acquire a training sequence number parameter in the channel switching information.