CN106060811A

CN106060811A - User behavior privacy protection method based on channel interference

Info

Publication number: CN106060811A
Application number: CN201610529103.6A
Authority: CN
Inventors: 房鼎益; 张洁; 汤战勇; 李蓉; 陈晓江; 龚晓庆; 陈�峰; 叶贵鑫
Original assignee: NORTHWEST UNIVERSITY
Current assignee: NORTHWEST UNIVERSITY
Priority date: 2016-07-05
Filing date: 2016-07-05
Publication date: 2016-10-26
Anticipated expiration: 2036-07-05
Also published as: CN106060811B

Abstract

The invention provides a method for protecting user behavior privacy based on channel interference. The method finds the channel of the attacker's wireless router by screening surrounding wireless signals, and then uses a secure wireless router to influence the attacker by switching channels. The wireless router, so that the data packets received by the attacker will be lost, so as to achieve the purpose of protecting privacy. This scheme proves that wireless signals may leak user privacy from another perspective, and proposes a channel interference method to protect user privacy behavior; at the same time, this method can be used to study how to allocate channels or bandwidth reasonably to avoid channel interference so that the communication system has greater throughput.

Description

A method of protecting user behavior privacy based on channel interference

技术领域technical field

本发明涉及一种物联网中的隐私保护技术，具体涉及一种基于信道干扰的保护用户隐私行为的方法。The invention relates to a privacy protection technology in the Internet of Things, in particular to a method for protecting user privacy behavior based on channel interference.

背景技术Background technique

WiFi是物联网的重要组成部分，最近几年WiFi更是用来做室内定位、目标追踪、手势识别、按键检测、唇语识别等。但是，在利用WiFi技术的同时，却往往忽略了WiFi也可能泄露用户的隐私的安全隐患。WiFi is an important part of the Internet of Things. In recent years, WiFi has been used for indoor positioning, target tracking, gesture recognition, key detection, lip language recognition, etc. However, while utilizing the WiFi technology, the potential safety hazard that the WiFi may also leak the user's privacy is often overlooked.

例如，WiHear系统使残疾人仅仅通过语言指令就可以和设备进行交互，让设备做他想要做的事情，极大地方便了残疾人的生活。因为WiHear系统用当前的无线信号发射器就可以实现，所以，当WiHear系统被用在一些隐私的场所时，比如在公司会议有一个无线路由器，那么公司开会的内容很有可能被攻击者获取，进而攻击者可能会获取到公司的商业机密，对公司会造成不可估量的经济损失。WiKey系统实现了细粒度的按键检测，如果攻击者在公司高层领导办公室安装一个无线信号发射端，那么领导在电脑上输入的信息很有可能被攻击者获取。我们之前的工作，WiPass系统证明了WiFi信号会泄露用户的设备解锁密码。For example, the WiHear system enables the disabled to interact with the device only through language instructions, allowing the device to do what he wants, which greatly facilitates the life of the disabled. Because the WiHear system can be implemented with the current wireless signal transmitter, when the WiHear system is used in some private places, such as a wireless router in a company meeting, the content of the company meeting is likely to be obtained by an attacker. Furthermore, the attacker may obtain the company's commercial secrets, which will cause immeasurable economic losses to the company. The WiKey system realizes fine-grained keystroke detection. If an attacker installs a wireless signal transmitter in the office of the company's top leaders, the information entered by the leader on the computer is likely to be obtained by the attacker. Our previous work, the WiPass system, demonstrated that WiFi signals can reveal the user's device unlock password.

802.11b/g/n协议中，2.4GHz频段被划分成了14个信道，如图1所示，而在中国实际使用13个，但是并不是所有的信道都能够同时使用。这是因为在相邻的信道之间是存在部分重叠的，其实真正互不干扰的信道仅仅只有3个，信道1，信道6和信道11(如果设备支持的话，信道2，信道7和信道12；信道3，信道8和信道13也可以作为互不干扰的信道)。这些信道之间的间隔是固定的，都是5MHz。例如1信道和3信道之间的间隔为10MHz。除了信道之间的间隔是定值之外，每个信道所占的带宽也是固定的，都是22MHz。例如，图1中所表示的1、6、11信道所占的信道带宽都是22MHz，这就造成了信道之间可能会存在或多多少的重叠，也就造成了或多或少的干扰。相应的为了防止这些干扰，相关标准作出了定义，如图2所示。图中定义，如果两个信道之间的距离是11MHz，要使得信号之间干扰最低，那么信号强度值必须相对于其峰值功率低30dB，如果两个信道距离22MHz，那么是50dB。然而，重叠的4个信道中，它们的影响也是不同的，因为他们之间重叠的程度是不同的；例如，信道2与信道1有77.27％重叠，而信道3与信道1有54.55％的重叠。当两个无线信号发射端之间存在信道干扰，则会造成一方丢包，使其吞吐量下降。In the 802.11b/g/n protocol, the 2.4GHz frequency band is divided into 14 channels, as shown in Figure 1, and 13 channels are actually used in China, but not all channels can be used at the same time. This is because there is partial overlap between adjacent channels. In fact, there are only 3 channels that do not interfere with each other, channel 1, channel 6 and channel 11 (if the device supports it, channel 2, channel 7 and channel 12 ; channel 3, channel 8 and channel 13 can also be used as non-interfering channels). The spacing between these channels is fixed, all 5MHz. For example, the interval between channel 1 and channel 3 is 10MHz. In addition to the fixed value of the interval between channels, the bandwidth occupied by each channel is also fixed, which is 22MHz. For example, channels 1, 6, and 11 shown in FIG. 1 all occupy a channel bandwidth of 22 MHz, which may cause more or less overlap between channels, and thus cause more or less interference. Correspondingly, in order to prevent these interferences, relevant standards have made definitions, as shown in Figure 2. As defined in the figure, if the distance between the two channels is 11MHz, to minimize the interference between the signals, the signal strength value must be 30dB lower than its peak power, and if the distance between the two channels is 22MHz, then it is 50dB. However, among the 4 channels that overlap, their impact is also different because the degree of overlap between them is different; for example, channel 2 overlaps channel 1 by 77.27%, while channel 3 overlaps channel 1 by 54.55% . When there is channel interference between two wireless signal transmitters, one party will lose packets and its throughput will decrease.

现有的通信系统把信道干扰认为是有害的，利用各种技术来消除干扰。现有的关于无线干扰的研究分为三类：第一类是关于干扰机理的研究，这一部分研究主要关注干扰现象产生的原因，为下面两类研究提供依据；第二类研究是关于干扰避免的研究，这部分研究致力于寻找一种有效地干扰避免方法；第三类研究是关于干扰共存的研究，在无法有效避免干扰的情况下，干扰与真正的数据通信收发方将不得不共同占用频谱资源，这部分研究致力于如何改善收发方的通信性能。Existing communication systems regard channel interference as harmful and use various techniques to eliminate the interference. The existing research on wireless interference is divided into three categories: the first category is the research on the interference mechanism, this part of the research mainly focuses on the reasons for the interference phenomenon, and provides the basis for the following two types of research; the second type of research is on interference avoidance This part of the research is dedicated to finding an effective interference avoidance method; the third type of research is the research on the coexistence of interference. If the interference cannot be effectively avoided, the interference and the real data communication sender and receiver will have to share Spectrum resources, this part of the research is dedicated to how to improve the communication performance of the transceiver.

发明内容Contents of the invention

针对上述现有技术中提到的周围环境中存在攻击者的无线路由器，而导致信息被窃取的问题，本发明的目的在于，提供一种基于信道干扰的保护用户行为隐私的方法，该方法利用信道干扰的方法来抵御WiFi攻击，以达到保护用户隐私行为的目的。Aiming at the problem of information being stolen due to the presence of an attacker’s wireless router in the surrounding environment mentioned in the prior art, the purpose of the present invention is to provide a method for protecting user behavior privacy based on channel interference. The method of channel interference is used to defend against WiFi attacks, so as to achieve the purpose of protecting user privacy behavior.

为了实现上述任务，本发明采用以下技术方案：In order to achieve the above tasks, the present invention adopts the following technical solutions:

一种基于信道干扰的保护用户行为隐私的方法，包括以下步骤：A method for protecting user behavior privacy based on channel interference, comprising the following steps:

步骤一，信道检测Step 1, channel detection

用户利用WiFi信号分析仪来获取当前位置周围路由器发出的无线信号的接收强度，根据无线信号的接收强度得到用户与周围路由器之间的距离S；根据得到的距离S，选出与当前位置距离小于4米以内的无线路由器；根据选出的无线路由器，分析得出攻击者的无线路由器的信道；The user uses the WiFi signal analyzer to obtain the receiving strength of the wireless signal sent by the routers around the current location, and according to the receiving strength of the wireless signal, the distance S between the user and the surrounding routers is obtained; according to the obtained distance S, the distance from the current location is less than A wireless router within 4 meters; according to the selected wireless router, analyze the channel of the attacker's wireless router;

步骤二，信道切换Step 2, channel switching

用户在周围的路由器中选取一个可信任的安全的路由器，将安全的路由器的信道切换到可以干扰攻击者无线路由器的信道，使攻击者的无线路由器出现丢包情况，这样攻击者就无法解码路由器获取的数据包，以达到保护用户行为隐私的目的。The user selects a trusted and secure router among the surrounding routers, switches the channel of the secure router to a channel that can interfere with the attacker's wireless router, and causes the attacker's wireless router to lose packets, so that the attacker cannot decode the router. Obtained data packets to achieve the purpose of protecting the privacy of user behavior.

进一步地，所述的安全的无线路由器选择切换信道的方法包括：Further, the method for selecting and switching channels by the secure wireless router includes:

(1)选择可用信道，可用信道是指可以影响攻击者无线路由器的信道；(1) Select an available channel, and an available channel refers to a channel that can affect the attacker's wireless router;

(2)计算安全的无线路由器切换到可用信道后，攻击者无线路由器的丢包率Packet Loss Rate：(2) Calculate the Packet Loss Rate of the attacker's wireless router after the secure wireless router switches to an available channel:

$P P a a c c k k e e t t L L o o s the s s the s R R a a t t e e = = \frac{R R V V o o f f R R P P - - I I V V o o f f R R P P}{R R V V o o f f R R P P}$

上式中，RV of RP代表的是当两个无线信号发射端之间不存在信道干扰时，安全的无线路由器所接收到的数据包的个数；IV of RP代表的是当两个无线信号发射端之间存在信道干扰时安全的无线路由器所接收到的数据包的个数；In the above formula, RV of RP represents the number of data packets received by the secure wireless router when there is no channel interference between the two wireless signal transmitters; IV of RP represents the number of data packets received by the secure wireless router when two wireless signal transmitters The number of data packets received by the secure wireless router when there is channel interference between the transmitters;

(3)计算安全的无线路由器切换到可用信道后，对攻击者无线路由器信道造成的干扰强度IS：(3) Calculate the interference intensity IS caused by the attacker's wireless router channel after the secure wireless router switches to the available channel:

$I I S S = = {Σ Σ}_{i i = = 00}^{R R P P} \frac{{RSSI RSSI}_{i i__n no o o i i s the s e e__r r e e m m o o v v a a l l}}{R R P P}$

上式中，RP代表的是安全的无线路由器所接收到的数据包的个数；RSSI_{i_noise_removal}代表的是接收到的数据包去除噪声之后的RSSI值；In the above formula, RP represents the number of data packets received by the secure wireless router; RSSI _{i_noise_removal} represents the RSSI value of the received data packets after noise removal;

(4)计算安全的无线路由器切换到可用信道后，攻击者无线路由器信道数据包的活跃率AR：(4) Calculate the activity rate AR of the attacker's wireless router channel data packet after the secure wireless router switches to the available channel:

$A A R R = = {Σ Σ}_{i i = = 00}^{R R P P} {U u}_{i i},, {U u}_{i i} = = \{\begin{matrix} i i f f \frac{| | {RSSI RSSI}_{i i} + + {Noise noise}_{i i} | |}{{RSSI RSSI}_{i i__n no o o i i s the s e e__r r e e m m o o v v a a l l}} &GreaterEqual; &Greater Equal; 11,, & {U u}_{i i} = = 11 \\ o o t t h h e e r r,, & {U u}_{i i} = = 00 \end{matrix}$

上式中，Noise_i代表是安全的无线路由器获取到的CSI数据中包含的噪声量的值，i为CSI数据序列的长度，也即接收到的数据包的个数；RSSI_i表示接收到的CSI数据的RSSI值；In the above formula, Noise _i represents the value of the amount of noise contained in the CSI data obtained by the secure wireless router, i is the length of the CSI data sequence, that is, the number of received data packets; RSSI _i represents the received RSSI value of CSI data;

(5)在所有的可用信道中，选择安全的无线路由器切换到可用信道后，攻击者的无线路由器丢包率最大、信道数据包活跃率最小同时干扰强度最大的可用信道，将安全的无线路由器的信道切换到这个可用信道即可。(5) Among all the available channels, after selecting the safe wireless router to switch to the available channel, the available channel with the largest packet loss rate of the attacker's wireless router, the smallest active rate of channel data packets and the largest interference intensity will be transferred to the safe wireless router. switch to this available channel.

进一步地，所述的步骤一中分析得出攻击者无线路由器信道的具体方法包括：Further, the specific method for analyzing and obtaining the channel of the attacker's wireless router in the step 1 includes:

a.若选出的无线路由器的信道都处在同一个信道，那么认为攻击者的无线路由器的信道也处于该信道中；a. If the channels of the selected wireless routers are all in the same channel, then it is considered that the channel of the attacker's wireless router is also in the channel;

b.若选出的无线路由器的信道处于两个不同的信道，且处于的两个不同的信道相差为5或10，则认为攻击者的无线路由器的信道处于这两个不同的信道中；b. If the channel of the selected wireless router is in two different channels, and the difference between the two different channels is 5 or 10, then it is considered that the channel of the wireless router of the attacker is in the two different channels;

c.若选出的无线路由器的信道处于三个不同的信道，则认为攻击者的无线路由器的信道也处于这三个不同的信道中。c. If the channel of the selected wireless router is in three different channels, it is considered that the channel of the wireless router of the attacker is also in the three different channels.

本发明与现有技术相比具有以下技术特点：Compared with the prior art, the present invention has the following technical characteristics:

1.本发明与现有技术采用完全不同的思路，利用了信道干扰的特性来进行隐私保护，对攻击者无线信号造成影响，使攻击者不能通过无线方式获取有效、完整的信息，从而不能解码出有价值的隐私信息，以达到保护用户隐私的目的；这种思路为隐私保护研究提供了一种新的方向，同时具有良好的效果；1. The present invention adopts a completely different idea from the prior art, and uses the characteristics of channel interference to protect privacy, which affects the wireless signal of the attacker, so that the attacker cannot obtain effective and complete information wirelessly, so that it cannot be decoded Provide valuable privacy information to achieve the purpose of protecting user privacy; this idea provides a new direction for privacy protection research, and has good results;

2.本发明通过实验来验证了以信道干扰的方式来保护用户行为隐私的有效性，经过实验验证表明，当存在信道干扰时，能对攻击者的无线路由器造成显著的影响，因此可以有效地抵御攻击者识别用户隐私的行为；2. The present invention has verified the effectiveness of protecting user behavior privacy by way of channel interference through experiments. Experimental verification shows that when there is channel interference, it can have a significant impact on the attacker's wireless router, so it can effectively Resist the behavior of attackers to identify user privacy;

3.现有的行为识别系统还没有考虑隐私泄露的问题，本方案从另一个角度证明了无线信号可能泄露用户隐私，并提出了一个信道干扰的方法来保护用户的行为，给出了具体的信道干扰程度的量化指标；3. The existing behavior recognition system has not considered the issue of privacy leakage. This scheme proves that wireless signals may leak user privacy from another perspective, and proposes a channel interference method to protect user behavior, and gives a specific Quantitative index of channel interference degree;

4.通过本方案可以研究如何合理分配信道或者带宽来避免信道干扰使得通信系统具有更大的吞吐量。4. Through this scheme, it is possible to study how to allocate channels or bandwidth reasonably to avoid channel interference and make the communication system have greater throughput.

附图说明Description of drawings

图1为2.4GHz上信道的分布情况；Figure 1 shows the distribution of channels on 2.4GHz;

图2为2.4GHz的功率谱防护来防止相邻信道的干扰的示意图；Fig. 2 is a schematic diagram of 2.4GHz power spectrum protection to prevent adjacent channel interference;

图3(a)和图3(b)为同一位置在两个不同时刻时检测到的无线发射端信道情况的示意图；Fig. 3 (a) and Fig. 3 (b) are the schematic diagrams of the channel situation of the wireless transmitter detected at the same position at two different times;

图4(a)、图4(b)、图4(c)和图4(d)为安全的无线路由器与攻击者的无线路由器的信道处于不同情况时，安全的无线路由器接收到的数据包的个数、攻击者无线路由器丢包率、攻击者无线路由器干扰强度、攻击者无线路由器信道数据包活跃率的对比图；Figure 4(a), Figure 4(b), Figure 4(c) and Figure 4(d) are the data packets received by the secure wireless router when the channels of the secure wireless router and the attacker's wireless router are in different situations The comparison chart of the number of attacker wireless routers, the packet loss rate of the attacker wireless router, the interference intensity of the attacker wireless router, and the channel packet activity rate of the attacker wireless router;

图5(a)和图5(b)为当安全的无线路由器切换到与攻击者的无线路由器信道的相邻信道时，信道干扰的持续时间情况，分别为接收到的数据包的个数对比图和干扰强度、活跃率情况；Figure 5(a) and Figure 5(b) show the duration of channel interference when the secure wireless router switches to the adjacent channel of the attacker's wireless router channel, and are respectively the comparison of the number of received data packets Figure and interference intensity, activity rate;

图6(a)和图6(b)为当安全的无线路由器与攻击者的无线路由器处于不同距离时，切换安全的无线路由器的信道时信道干扰的情况，分别为接收到数据包的个数及丢包率的实验图、干扰强度和活跃率的实验图；Figure 6(a) and Figure 6(b) show the situation of channel interference when the secure wireless router and the attacker's wireless router are at different distances when switching the channel of the secure wireless router, respectively the number of received data packets And the experimental diagram of packet loss rate, the experimental diagram of interference intensity and activity rate;

图7为当攻击者的无线信号发射端分别为路由器和智能手机时，切换安全的无线路由器的信道对攻击者的无线信号发射端的信道干扰情况；Fig. 7 is when the attacker's wireless signal transmitter is a router and a smart phone respectively, switching the channel of a secure wireless router interferes with the channel of the attacker's wireless signal transmitter;

图8(a)为智能手机上解锁密码图案；图8(b)为解锁密码图案不同情况下解锁时的实验图；图8(c)为小键盘按键检测的键盘示意图；Fig. 8 (a) is the unlocking password pattern on the smart phone; Fig. 8 (b) is the experimental diagram when unlocking under different situations of the unlocking password pattern; Fig. 8 (c) is the keyboard schematic diagram of keypad key detection;

图9(a)为解锁密码案例的部署示意图；图9(b)为按键检测实验的部署示意图；Figure 9(a) is a schematic diagram of the deployment of the case of unlocking the password; Figure 9(b) is a schematic diagram of the deployment of the button detection experiment;

图10(a)为不存在信道干扰时解锁密码识别准确率的示意图；Fig. 10(a) is a schematic diagram of unlocking code identification accuracy when there is no channel interference;

图10(b)为不存在信道干扰时数字按键检测识别准确率的示意图；Figure 10(b) is a schematic diagram of the accuracy of digital key detection and recognition when there is no channel interference;

图11(a)为存在信道干扰时解锁密码识别准确率的示意图；Figure 11(a) is a schematic diagram of the recognition accuracy of the unlock password when there is channel interference;

图11(b)为存在信道干扰时数字按键检测识别准确率的示意图。Fig. 11(b) is a schematic diagram of the detection and recognition accuracy of digital keys when there is channel interference.

具体实施方式detailed description

本发明反其道而行之，因为利用无线信号来进行行为识别的本质是攻击者如果可以获取到用户做某种行为时对信号的影响，之后再对其进行去噪、提取特征、识别等步骤就可以解码出用户所做的行为；如果用户让攻击者获取不到他们做某种行为时对信号的影响，或者使他们获取到的数据不完整，那么他们最终解码出来的行为就是错误的。本发明就是基于这种思想，利用了信道干扰的特性来进行保护。主要通过信道检测和信道切换两步来进行保护。The present invention does the opposite, because the essence of behavior recognition using wireless signals is that if the attacker can obtain the influence of the user on the signal when he does a certain behavior, and then denoise it, extract features, identify it, etc. Steps can decode the behavior of the user; if the user prevents the attacker from obtaining the impact on the signal when they do a certain behavior, or makes the data they obtain incomplete, then the behavior they finally decode is wrong . The present invention is based on this idea and utilizes the characteristics of channel interference for protection. The protection is mainly carried out through two steps of channel detection and channel switching.

本发明的具体步骤如下：Concrete steps of the present invention are as follows:

步骤一，信道检测Step 1, channel detection

如图3(a)和图3(b)所示，在同一位置不同时刻检测到的无线信号发射端的数目不同，有时可能检测到的信号强度也不同，准确判断哪个是攻击者的无线信号发射端，进而检测出攻击者无线信号发射端的信道。As shown in Figure 3(a) and Figure 3(b), the number of wireless signal transmitters detected at the same location at different times is different, and sometimes the detected signal strengths may also be different, so it can be accurately judged which one is the attacker's wireless signal transmitter end, and then detect the channel of the attacker's wireless signal transmitter.

用户利用WiFi信号分析仪来获取当前位置周围路由器发出的无线信号的接收强度，根据无线信号的接收强度得到用户与周围路由器之间的距离S；根据得到的距离S，选出与当前位置距离小于4米以内的无线路由器；该距离可通过WiHear系统、WiKey系统以及其他行为识别系统中用户与无线信号发射端的距离得到；The user uses the WiFi signal analyzer to obtain the receiving strength of the wireless signal sent by the routers around the current location, and according to the receiving strength of the wireless signal, the distance S between the user and the surrounding routers is obtained; according to the obtained distance S, the distance from the current location is less than A wireless router within 4 meters; the distance can be obtained from the distance between the user and the wireless signal transmitter in the WiHear system, WiKey system and other behavior recognition systems;

根据选出的无线路由器，分析得出攻击者的无线路由器的信道；According to the selected wireless router, analyze the channel of the attacker's wireless router;

具体地，步骤一中分析得出攻击者无线路由器信道(802.11b/g/n协议)的具体方法包括：Specifically, the specific methods for analyzing and obtaining the attacker's wireless router channel (802.11b/g/n protocol) in step 1 include:

a.若选出的无线路由器的信道都处在同一个信道(选取出来的路由器的信道都处在信道1/信道6/信道11)，那么认为攻击者的无线路由器的信道也处于该信道(信道1/信道6/信道11)中；a. If the channels of the selected wireless routers are all in the same channel (the channels of the selected routers are all in channel 1/channel 6/channel 11), then it is considered that the channel of the attacker's wireless router is also in this channel ( channel 1/channel 6/channel 11);

b.若选出的无线路由器的信道处于两个不同的信道，且处于的两个不同的信道相差为5(选取出来的路由器的信道处于信道1和信道6/信道6和信道11)或10(选取出来的路由器的信道处于信道1和信道11)，则认为攻击者的无线路由器的信道处于这两个不同的信道中；那么此时并不需要准确知道攻击者的无线路由器的信道，只需要把安全的路由器的信道切换到一个合适的信道即可；b. If the channel of the selected wireless router is in two different channels, and the difference between the two different channels is 5 (the channel of the selected router is in channel 1 and channel 6/channel 6 and channel 11) or 10 (the channel of the selected router is in channel 1 and channel 11), then it is considered that the channel of the wireless router of the attacker is in these two different channels; You need to switch the channel of the secure router to a suitable channel;

c.若选出的无线路由器的信道处于三个不同的信道(选取出来的路由器的信道处于信道1，信道6和信道11)，则认为攻击者的无线路由器的信道也处于这三个不同的信道中；那么此时攻击者的路由器的信道不需要准确知道，只需要把安全的路由器的信道进行来回切换即可。c. If the channel of the selected wireless router is in three different channels (the channel of the selected router is in channel 1, channel 6 and channel 11), then it is considered that the channel of the attacker's wireless router is also in these three different channels In the channel; then the channel of the attacker's router does not need to be accurately known at this time, it only needs to switch the channel of the secure router back and forth.

分析：当两个无线信号发射端是邻居，并且他们的信道处于同一信道，此时他们之间的信道干扰最大，之后依次递减，那么我们可根据此获得的干扰矩阵如下所示：Analysis: When two wireless signal transmitters are neighbors and their channels are in the same channel, the channel interference between them is the largest at this time, and then decreases in turn, then the interference matrix we can obtain based on this is as follows:

上面的矩阵是计算两个无线信号发射端之间的信道干扰，例如，第一行第一列数据代表两个无线信号发射端处于同一信道，则此时信道干扰是最大的，可认为其是10⁵，第一行第二列数据代表两个无线信号发射端的信道一个处于信道1，一个处于信道2，此时信道干扰值为2⁴，第一行第三列数据代表两个无线信号发射端的信道一个处于1，一个处于3，此时信道干扰值为2³，第一行第四列数据代表两个无线信号发射端的信道一个处于1，一个处于4，此时信道干扰值为2²，第一行第五列数据代表两个无线信号发射端的信道一个处于1，一个处于5，此时信道干扰值为2，当两个无线信号发射端的信道相差>5，则他们之间不存在信道干扰，信道干扰值为0。因为他们之间的信道不存在重叠部分。在该矩阵中的数字只是把不同情况下的信道干扰进行量化，也可以分别用5,4,3,2,1来量化信道干扰。通过该矩阵表明，信道干扰是一种可行的方案。The above matrix is to calculate the channel interference between two wireless signal transmitters. For example, the data in the first row and the first column represent that the two wireless signal transmitters are in the same channel. At this time, the channel interference is the largest, which can be considered as ¹⁰ ⁵ , the data in the first row and the second column represent the channels of the two wireless signal transmitters. One channel of the terminal is at 1 and the other is at 3. At this time, the channel interference value is 2 ³ . The data in the fourth column of the first row represents the channels of the two wireless signal transmitters. One is at 1 and the other is at 4. At this time, the channel interference value is 2 ² , the data in the fifth column of the first row indicates that one of the channels of the two wireless signal transmitters is at 1, and the other is at 5. At this time, the channel interference value is 2. When the channel difference between the two wireless signal transmitters is >5, there is no Channel interference, the channel interference value is 0. Because the channels between them do not overlap. The numbers in the matrix only quantify the channel interference in different situations, and 5, 4, 3, 2, and 1 can also be used to quantify the channel interference. This matrix shows that channel interference is a feasible solution.

步骤二，信道切换Step 2, channel switching

具体地，安全的无线路由器选择切换信道的方法包括：Specifically, the method for the safe wireless router to select and switch channels includes:

(1)选择可用信道，可用信道是指可以影响攻击者无线路由器的信道；这里的可用信道可以有多个；(1) select the available channel, the available channel refers to the channel that can affect the attacker's wireless router; there can be multiple available channels here;

设置信道干扰评估指标，评估指标包括接收到的数据包的个数、丢包率、干扰强度以及活跃率；Set the channel interference evaluation index, the evaluation index includes the number of received data packets, packet loss rate, interference intensity and activity rate;

上述的接收到的数据包的个数是指安全的无线路由器切换到可用信道后，其所接收到的数据包的个数(The number of received packets)：The above-mentioned number of received data packets refers to the number of data packets received by the secure wireless router after switching to an available channel (The number of received packets):

路由器获取到的数据是一系列CSI数据，CSI数据序列的长度就是接收到的数据包的个数。The data obtained by the router is a series of CSI data, and the length of the CSI data sequence is the number of received data packets.

上式中，RV of RP代表的是当两个无线信号发射端之间不存在信道干扰时，安全的无线路由器所接收到的数据包的个数，即安全的无线路由器还未切换到可用信道时；IVof RP代表的是当两个无线信号发射端之间存在信道干扰时安全的无线路由器所接收到的数据包的个数，即安全的无线路由器已经切换到可用信道时；这里的两个无线信号发射端是指安全的无线路由器和攻击者的无线路由器；In the above formula, RV of RP represents the number of data packets received by the secure wireless router when there is no channel interference between the two wireless signal transmitters, that is, the secure wireless router has not switched to an available channel When; IVof RP represents the number of data packets received by the secure wireless router when there is channel interference between the two wireless signal transmitters, that is, when the secure wireless router has switched to an available channel; here the two The wireless signal transmitter refers to the secure wireless router and the attacker's wireless router;

在802.11b/g/n协议中，根据上述的评估干扰程度的指标的实验结果，对安全的路由器的信道切换可分为如下几种情况来进行：In the 802.11b/g/n protocol, according to the above-mentioned experimental results of the indicators for evaluating the degree of interference, the channel switching of the secure router can be divided into the following situations:

a.若选取出来的路由器的信道都处在同一个信道，当攻击者的无线路由器处于信道1时，用户可以把安全的路由器的信道切换到信道2；当攻击者的路由器处于信道6时，用户可以把安全的路由器的信道切换到信道5或信道7；当攻击者的路由器处于信道11时，用户可以把安全的路由器的信道切换到信道10或信道12；a. If the channels of the selected routers are all in the same channel, when the attacker's wireless router is in channel 1, the user can switch the channel of the secure router to channel 2; when the attacker's router is in channel 6, The user can switch the channel of the secure router to channel 5 or channel 7; when the attacker's router is in channel 11, the user can switch the channel of the secure router to channel 10 or channel 12;

b.若选取出来的路由器的信道处于两个不同的信道，且处于的信道相差为5：当选取出来的路由器的信道处于信道1和信道6，用户可以把安全的路由器的信道切换到信道3或信道4；当选取出来的路由器处于信道6和信道11，用户可以把安全的路由器的信道切换到信道8或信道9；b. If the channel of the selected router is in two different channels, and the channel difference is 5: When the channel of the selected router is in channel 1 and channel 6, the user can switch the channel of the safe router to channel 3 or channel 4; when the selected router is in channel 6 and channel 11, the user can switch the channel of the secure router to channel 8 or channel 9;

c.若选取出来的路由器的信道处于两个不同的信道，且处于的信道相差为10：当选取出来的路由器的信道处于信道1和信道11，用户可以把安全的路由器的信道在信道2和信道10之间来回切换或在信道2和信道12之间来回切换；c. If the channel of the selected router is in two different channels, and the channel difference is 10: When the channel of the selected router is in channel 1 and channel 11, the user can set the channel of the safe router in channel 2 and channel 11. switch back and forth between channel 10 or switch back and forth between channel 2 and channel 12;

d.若选取出来的路由器的信道处于三个不同的信道，当选取出来的路由器的信道处于信道1，信道6和信道11，用户可以把安全的路由器的信道在信道2，信道5和信道10之间来回切换，或在信道2，信道7和信道10之间来回切换，或在信道2，信道5和信道12之间来回切换，或在信道2，信道7和信道12之间来回切换。d. If the channel of the selected router is in three different channels, when the channel of the selected router is in channel 1, channel 6 and channel 11, the user can set the channel of the secure router in channel 2, channel 5 and channel 10 Switch back and forth between channels, or switch back and forth between channel 2, channel 7 and channel 10, or switch back and forth between channel 2, channel 5 and channel 12, or switch back and forth between channel 2, channel 7 and channel 12.

实验部分：Experimental part:

发明人做了几组实验来证明当两个无线信号发射端是邻居，且当他们处于相邻信道时，他们之间是存在信道干扰的。如图4、图5、图6、图7所示，图4说明当两个无线信号发射端的信道相差为1的时候，他们之间的信道干扰是最大的；The inventor has done several sets of experiments to prove that when two wireless signal transmitters are neighbors and they are in adjacent channels, there is channel interference between them. As shown in Figure 4, Figure 5, Figure 6, and Figure 7, Figure 4 shows that when the channel difference between the two wireless signal transmitters is 1, the channel interference between them is the largest;

图5说明，在90s之后，他们之间仍然存在信道干扰，90s对于用户来说可以做很多事了，而且在90s之后用户还可以继续检测攻击者的信道并切换信道对其进行干扰；Figure 5 shows that after 90s, there is still channel interference between them, 90s can do a lot of things for the user, and after 90s, the user can continue to detect the attacker's channel and switch channels to interfere with it;

图6说明，当两个无线信号发射端距离<3m的时候，这时候他们之间的信道干扰是较强的，当>3m之后，他们之间的信道干扰会下降，但是也会有干扰；Figure 6 shows that when the distance between two wireless signal transmitters is <3m, the channel interference between them is strong at this time, and when >3m, the channel interference between them will decrease, but there will be interference;

图7说明，当攻击者用不同的无线信号发射端的时候，信道干扰都是有效的。因此信道干扰可以用来保护用户行为。Figure 7 illustrates that channel interference is effective when the attacker uses different wireless signal transmitters. Therefore channel interference can be used to protect user behavior.

案例：case:

发明人研究了两个案例，一个是智能手机的解锁密码，做了15种解锁密码；一个是按键检测，做了键盘右侧的数字键盘上按键“0”到按键“9”；如图8所示。The inventor studied two cases, one is the unlocking password of the smart phone, and made 15 kinds of unlocking passwords; the other is key detection, and made the button "0" to the button "9" on the numeric keypad on the right side of the keyboard; as shown in Figure 8 shown.

解锁密码和按键检测的实验部署图如图9所示。AP代表的是路由器，实验中用得就是普通的TP-LINK家用路由器，实验用Intel 5300网卡来接收数据，Laptop作为接收数据的显示终端，路由器与网卡接收器之间的距离为1m，手机放置在路由器与网卡之间进行解锁密码，键盘放置在路由器与网卡之间进行解锁密码。The experimental deployment diagram of unlocking password and key detection is shown in Figure 9. AP represents a router. In the experiment, an ordinary TP-LINK home router is used. The experiment uses an Intel 5300 network card to receive data. Laptop is used as a display terminal for receiving data. The distance between the router and the receiver of the network card is 1m. Unlock the password between the router and the network card, and place the keyboard between the router and the network card to unlock the password.

路由器用来发射无线信号，网卡用来接收无线信号，接收数据从解锁密码未开始之前开始接收数据，当解锁密码完成之后结束无线信号数据的接收，键盘数据的接收也是类似的。接收到的数据是CSI序列，每一个CSI数据里面包含30个子载波，每个子载波的数据都包含信号的幅值和相位。The router is used to transmit wireless signals, and the network card is used to receive wireless signals. The received data begins to receive data before the unlock password starts. When the unlock password is completed, the wireless signal data reception ends. The keyboard data reception is also similar. The received data is a CSI sequence, and each CSI data contains 30 subcarriers, and the data of each subcarrier includes the amplitude and phase of the signal.

在获取到数据之后，我们用离散小波变换进行去噪，然后用滑动窗口确定解锁密码/按键是什么开始的，什么时候结束的，最后用动态时间规整来识别出解锁密码/按键是什么。After acquiring the data, we use discrete wavelet transform to denoise, then use sliding window to determine when the unlock password/key starts and when it ends, and finally use dynamic time warping to identify what the unlock password/key is.

当我们需要保护解锁密码/按键，我们在解锁之前/按键之前把一个安全的无线信号发射端的信道切换到一个合适的信道来干扰攻击者的信道，之后再进行解锁/按键。When we need to protect the unlock password/key, we switch the channel of a safe wireless signal transmitter to a suitable channel to interfere with the attacker's channel before unlocking/keying, and then unlock/key.

实验结果表明，当不存在信道干扰的时候，识别的准确率较高，15种解锁密码的平均识别准确率为82.33％，10个数字按键的平均识别准确率为92％；如图10所示。当存在信道干扰的时候，识别的准确率明显下降，15种解锁密码的平均识别准确率为22.33％，10个数字按键的平均识别准确率为42％，如图11所示。因此，信道干扰可以有效地抵御攻击者识别用户的隐私行为。The experimental results show that when there is no channel interference, the recognition accuracy is high, the average recognition accuracy of 15 unlocking passwords is 82.33%, and the average recognition accuracy of 10 digital keys is 92%; as shown in Figure 10 . When there is channel interference, the recognition accuracy drops significantly. The average recognition accuracy of 15 unlocking passwords is 22.33%, and the average recognition accuracy of 10 digital keys is 42%, as shown in Figure 11. Therefore, channel interference can be effective against attackers to identify users' private behaviors.

Claims

1. A method for protecting user behavior privacy based on channel interference, characterized in that, comprising the following steps:

Step 1, channel detection

The user uses the WiFi signal analyzer to obtain the receiving strength of the wireless signal sent by the routers around the current location, and according to the receiving strength of the wireless signal, the distance S between the user and the surrounding routers is obtained; according to the obtained distance S, the distance from the current location is less than A wireless router within 4 meters; according to the selected wireless router, analyze the channel of the attacker's wireless router;

Step 2, channel switching

The user selects a trusted and secure router among the surrounding routers, switches the channel of the secure router to a channel that can interfere with the attacker's wireless router, and causes the attacker's wireless router to lose packets, so that the attacker cannot decode the router. Obtained data packets to achieve the purpose of protecting the privacy of user behavior.

2. The method for protecting user behavior privacy based on channel interference as claimed in claim 1, wherein the method for selecting and switching channels by the safe wireless router comprises:

(1) Select an available channel, and an available channel refers to a channel that can affect the attacker's wireless router;

(2) Calculate the packet loss rate of the attacker's wireless router PacketLoss Rate after the secure wireless router switches to an available channel:

P P a a c c k k e e t t L L o o s the s s the s R R a a t t e e = = \frac{R R V V o o f f R R P P - - I I V V o o f f R R P P}{R R V V o o f f R R P P}

In the above formula, RV of RP represents the number of data packets received by the secure wireless router when there is no channel interference between the two wireless signal transmitters; IV of RP represents the number of data packets received by the secure wireless router when two wireless signal transmitters The number of data packets received by the secure wireless router when there is channel interference between the transmitters;

(3) Calculate the interference intensity IS caused by the attacker's wireless router channel after the secure wireless router switches to the available channel:

I I S S = = {Σ Σ}_{i i = = 00}^{R R P P} \frac{{RSSI RSSI}_{i i__n no o o i i s the s e e__r r e e m m o o v v a a l l}}{R R P P}

In the above formula, RP represents the number of data packets received by the secure wireless router; RSSI _{i_noise_removal} represents the RSSI value of the received data packets after noise removal;

(4) Calculate the activity rate AR of the attacker's wireless router channel data packet after the secure wireless router switches to the available channel:

A A R R = = {Σ Σ}_{i i = = 00}^{R R P P} {U u}_{i i},, {U u}_{i i} = = \{\begin{matrix} i i f f \frac{| | {RSSI RSSI}_{i i} + + {Noise noise}_{i i} | |}{{RSSI RSSI}_{i i__n no o o i i s the s e e__r r e e m m o o v v a a l l}} &GreaterEqual; &Greater Equal; 11,, & {U u}_{i i} = = 11 \\ o o t t h h e e r r,, & {U u}_{i i} = = 00 \end{matrix}

In the above formula, Noise _i represents the value of the amount of noise contained in the CSI data obtained by the secure wireless router, i is the length of the CSI data sequence, that is, the number of received data packets; RSSI _i represents the received RSSI value of CSI data;

(5) Among all the available channels, after selecting the safe wireless router to switch to the available channel, the available channel with the largest packet loss rate of the attacker's wireless router, the smallest active rate of channel data packets and the largest interference intensity will be transferred to the safe wireless router. switch to this available channel.

3. the method for protecting the user's behavior privacy based on channel interference as claimed in claim 1, is characterized in that, in the described step 1, analyze and obtain the concrete method of assailant's wireless router channel comprising:

a. If the channels of the selected wireless routers are all in the same channel, then it is considered that the channel of the attacker's wireless router is also in the channel;

b. If the channel of the selected wireless router is in two different channels, and the difference between the two different channels is 5 or 10, then it is considered that the channel of the wireless router of the attacker is in the two different channels;

c. If the channel of the selected wireless router is in three different channels, it is considered that the channel of the wireless router of the attacker is also in the three different channels.