Information processing device, information processing method, and information processing program

Abstract

The present invention provides an information processing device that can accurately detect spoofing. [Solution] The information processing device includes a receiving unit that receives a positioning signal including time information, a high-precision clock generation unit that generates a high-precision clock, a clock generation unit that generates a clock based on the positioning signal received by the receiving unit, and a determination unit that compares the frequency of the clock generated by the clock generation unit with the frequency of the high-precision clock generated by the high-precision clock generation unit and determines whether or not a spoofing signal exists in the positioning signal received by the receiving unit.

Description

Technical Field

[0001] The present invention relates to an information processing device, an information processing method, and an information processing program for detecting spoofing.

Background Art

[0002] Conventionally, position information is measured by receiving positioning signals from satellites. In general, positioning using positioning signals from GNSS (Global Navigation Satellite System) satellites is widely known. Meanwhile, in recent years, spoofing has sometimes been carried out, in which an entity impersonates a satellite and transmits a fake positioning signal to tamper with the positioning result of a receiver that performs positioning. As described above, when subjected to spoofing, the positioning result will be incorrect, so it is necessary to develop the corresponding detection technology and mount it on the receiver.

[0003] Accordingly, Patent Document 1 discloses a technology that determines that spoofing is being received when a difference exceeding a threshold exists between a first time obtained by performing positioning based on a positioning signal and a second time acquired from an external source. In addition, Patent Document 2 discloses a technology that determines whether a legitimate navigation message is being received based on whether or not the time information included in sequentially received navigation messages has continuity.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of Invention

Problems to be Solved by the Invention

[0005] However, the technology described in Patent Document 1 requires obtaining the time from an external system, and there is a problem in that the accuracy of the obtained time is questionable, which may lead to inaccurate judgment results. Furthermore, in the technology described in Patent Document 2, if the time information of the navigation message included in the signal transmitted by the spoofer is set to a time close to the time information of the satellite's navigation message, there is a possibility that the signal transmitted by the spoofer may also be judged as a legitimate signal.

[0006] Therefore, the present invention aims to provide an information processing device, an information processing method, and an information processing program that can determine whether or not a receiver is being spoofed, and that can determine whether or not it is being spoofed more accurately than in the conventional method. [Means for solving the problem]

[0007] An information processing device in one embodiment of the present invention can be used for positioning and includes a receiving unit that receives a positioning signal including time information, a high-precision clock generating unit that generates a high-precision clock, a clock generating unit that generates a clock based on the positioning received by the receiving unit, and a determination unit that compares the frequency of the clock generated by the clock generating unit with the frequency of the high-precision clock generated by the high-precision clock generating unit and determines whether or not a spoofing signal exists in the positioning signal received by the receiving unit.

[0008] Furthermore, in the above-mentioned information processing device, the determination unit may determine that a spoofing signal exists if there is a difference of a predetermined threshold or more in the average frequency deviation (how much the clock deviates from the design frequency) between the clock generated by the clock generation unit and the high-precision clock generated by the high-precision clock generation unit within a predetermined period.

[0009] Furthermore, in the above-mentioned information processing device, the determination unit may change the threshold depending on whether the clock generated by the clock generation unit is a high-precision clock or not, and make a determination accordingly.

[0010] Furthermore, in the above-mentioned information processing device, the determination unit may also determine whether or not a spoofing signal exists if there is a difference of a predetermined threshold or more in the frequency stability, which indicates the variation in frequency or frequency deviation within a predetermined period, between the clock generated by the clock generation unit and the high-precision clock generated by the high-precision clock generation unit.

[0011] An information processing method in one embodiment of the present invention involves a computer performing the following steps: a receiving step of receiving a positioning signal including time information; a high-precision clock generation step of generating a high-precision clock based on a positioning signal from a positioning satellite; a clock generation step of performing positioning based on the positioning signal received by the receiving step and generating a clock; and a determination step of comparing the frequency of the clock generated by the clock generation step with the frequency of the high-precision clock generated by the high-precision clock generation step and determining whether or not a spoofing signal exists in the positioning signal received by the receiving step.

[0012] An information processing program in one embodiment of the present invention provides a computer with a receiving function that receives a positioning signal including time information, a high-precision clock generation function that generates a high-precision clock based on a positioning signal from a positioning satellite, a clock generation function that performs positioning based on the positioning signal received by the receiving function and generates a clock, and a determination function that compares the frequency of the clock generated by the clock generation function with the frequency of the high-precision clock generated by the high-precision clock generation function and determines whether or not a spoofing signal exists in the positioning signal received by the receiving function. [Effects of the Invention]

[0013] In one embodiment of the present invention, the information processing device can accurately determine the presence or absence of a spoofing signal by the receiver alone, by comparing the frequency of a pre-generated high-precision clock with the frequency of a clock generated based on a positioning signal that may include a signal from a received spoofer. [Brief explanation of the drawing]

[0014] [Figure 1] This is a system diagram showing an example of a communication system configuration. [Figure 2] This is a block diagram showing an example of a receiver configuration. [Figure 3] (a) is a figure showing the time change of the clock frequency deviation generated when the receiver performs high-precision positioning based on the positioning signal received using MADOCA and controls the oscillator frequency based on the positioning result, with a period of time intentionally set with and without spoofing. (b) is a figure showing the time change of the clock frequency deviation generated by standalone positioning by the receiver, with a period of time intentionally set with and without spoofing. [Figure 4] This flowchart shows an example of how the receiver works. [Modes for carrying out the invention]

[0015] The information processing apparatus, information processing method, and information processing program according to the present invention will be described with reference to the drawings.

[0016] <Embodiment> An information processing device 100, which is one embodiment of the present invention, will be described with reference to the drawings.

[0017] Figure 1 is a diagram illustrating a configuration example of a communication system. As shown in Figure 1, an information processing apparatus 100 receives positioning signals from satellites 10a to 10c (referred to as satellites 10 when no particular distinction is required), performs positioning, and calculates position information of its own device. Incidentally, the information processing apparatus 100 may receive a signal from a spoofer 20 that transmits a signal masquerading as a positioning signal. Basically, the spoofer 20 can disrupt the positioning of the information processing apparatus 100 or distort the time by transmitting false information. While such spoofing can be used for criminal purposes, it is a nuisance to the receiving side, so the development of a technology capable of detecting that spoofing is being received is urgently needed. The information processing apparatus 100 according to the present embodiment is an information processing apparatus capable of detecting that a signal from the spoofer 20 is being received when the signal from the spoofer 20 is received. The details will be described below.

[0018] Figure 2 is a block diagram illustrating a configuration example of the information processing apparatus 100.

[0019] As shown in Figure 2, the information processing apparatus 100 includes a communication unit 110, an input unit 120, an output unit 130, a storage unit 140, and a control unit 150, and the respective units may be connected to each other so as to be capable of mutual communication. The information processing apparatus 100 is a computer system having a positioning function, and may be implemented by, for example, a smartphone, a notebook PC, a tablet terminal, or the like, but is not limited thereto.

[0020] The communication unit 110 is a communication interface for communicating with an external device. The communication unit 110 receives positioning signals (which may include positioning augmentation signals) from the satellites 10a to 10c, and transmits the signals to the control unit 150. The communication unit 110 also receives MADOCA correction information and transmits the correction information to the control unit 150. Further, the communication unit 110 also transmits a signal to the control unit 150 when the signal from the spoofer 20 is received.

[0021] The input unit 120 is an input interface that receives input from a user of the information processing apparatus 100 and transmits the input to the control unit 150. The input unit 120 may be implemented by, for example, a keyboard, hard keys, software keys, a microphone, or the like provided in the information processing apparatus 100, but is not limited thereto.

[0022] The output unit 130 outputs information specified by the control unit 150. The output of the positioning result by the output unit 130 may be implemented in the form of an image, text, voice, or transmission to an external apparatus via the communication unit 110. When performing output by an image or text, the output unit 130 outputs the information to a monitor provided in the information processing apparatus 100 or a connected monitor, and when performing output by voice, the output unit 130 outputs voice information indicating the content of the specified information to a speaker provided in the information processing apparatus 100 or a connected speaker. The output unit 130 outputs information on whether a signal from the spoofer 200 is received in accordance with an instruction from the control unit 150. In addition, the output unit 130 may output a positioning result, or may output a generated clock.

[0023] The storage unit 140 is a storage medium that stores various programs and data required for the operation of the information processing apparatus 100. For example, the storage unit 140 may be implemented by an HDD (Hard Disc Drive), an SSD (Solid State Drive), a flash memory, or the like, but is not limited thereto. The programs stored by the storage unit 140 may include a program for receiving a positioning signal or a signal from the spoofer 200, performing positioning, and generating a clock. In addition, the programs stored by the storage unit 140 may also include a program for comparing the generated clock with a previously generated high-precision clock (a clock using time information of high-precision standalone positioning MADOCA-PPP) to detect whether spoofing is occurring.

[0024] The control unit 150 is a processor that controls each part of the information processing device 100, and realizes the functions that the information processing device 100 should perform by executing various programs by referring to various data stored in the memory unit 140. The control unit 150 performs positioning and generates a clock based on the positioning signal (including positioning signals from satellites and possibly including spoofing signals from the spoofer 200) received by the communication unit 110.

[0025] The control unit 150 includes, as functions implemented by the control unit 150, a high-precision clock generation unit 151, a receiving unit 152, a clock generation unit 153, a determination unit 154, and an output control unit 155.

[0026] The high-precision clock generation unit 151 is a crystal oscillator such as a TCXO (Temperature Controlled Crystal Oscillator) or OCXO (Oven Controlled Crystal Oscillator), or an atomic clock such as a CSAC (Chip Scale Atomic Clock) or Rubidium, or a GPS-DO (GPS Disciplined Oscillator) that, in addition to an oscillator, has a phase difference detector that detects the 1PPS phase difference between the satellite system clock and the oscillator by performing positioning, and a CPU that controls the oscillator's frequency based on the output of the phase difference detector. In the case of a GPS-DO, when the receiver unit 152 has not received a signal from the oscillator spoofer 200, it performs positioning using the phase difference detector based on the positioning signal received, and generates a high-precision clock by controlling the oscillator's frequency based on the 1PPS phase difference obtained by positioning. Alternatively, if the spoofing determination result is received from the determination unit 154 and the determination result is no spoofing, a high-precision clock may be generated by performing frequency control in the same procedure. The high-precision clock is a clock that is highly synchronized with the satellite system time system clock. In this embodiment, even if the high-precision clock generation unit 151 is equipped only with an oscillator and is not GPS-DO, the clock output by the oscillator is referred to as the high-precision clock. Furthermore, the positioning method of the phase difference detector is not limited to any particular positioning method, such as standalone positioning or MADOCA-PPP (MADOCA-Precise Point Positioning), a high-precision (centimeter-level) positioning method that utilizes MADOCA (Multi-GNSS Advanced Demonstration tool for Orbit and Clock Analysis), a high-precision positioning augmentation technology provided by the Japan Aerospace Exploration Agency (JAXA®) that estimates and distributes satellite orbit information (Orbit) and clock error information (Clock) in real time with high precision. The high-precision clock generation unit 151 transmits the generated high-precision clock to the receiving unit 152.

[0027] The receiving unit 152 receives the positioning signal via the communication unit 110 and transmits it to the high-precision clock generation unit 151 and the clock generation unit 153. The positioning signal received by the receiving unit 152 may be a signal from satellite 10 or a signal from spoofer 200.

[0028] The clock generation unit 153 performs positioning based on the positioning signal transmitted from the receiving unit 152 and generates a clock. The clock generated by the clock generation unit 153 is a high-precision clock when MADOCA is used, and is basically a lower-precision clock when standalone positioning is performed without MADOCA. The clock generation unit 153 may generate only one of either a clock using MADOCA or a clock without MADOCA, or it may be capable of generating both. The clock generation unit 153 transmits the generated clock to the determination unit 154. At this time, the clock generation unit 153 may also transmit information to the determination unit 154 indicating whether or not the generated clock is a high-precision clock.

[0029] The determination unit 154 compares the frequency of the clock generated by the clock generation unit 153 with the frequency of the high-precision clock generated by the high-precision clock generation unit 151, and determines whether or not a spoofing signal exists in the positioning signal received by the receiving unit 152. If it is determined that there is no spoofing, and the high-precision clock generation unit 151 is a GPS-DO, the spoofing detection performance can be improved by controlling the oscillator frequency using the measurement results of the phase difference detector to improve the frequency accuracy and frequency stability of the high-precision clock generation unit 151. Therefore, the determination unit 154 may transmit the determination result to the high-precision clock generation unit 151.

[0030] In this embodiment, the average of the clock's frequency deviation (how much the clock deviates from its design frequency) over a predetermined period is referred to as frequency accuracy. Furthermore, the variation in the clock's frequency or frequency deviation over a predetermined period is referred to as frequency stability in this embodiment. The determination unit 154 determines that a spoofing signal exists if there is a difference of more than a predetermined threshold in the magnitude of frequency stability or frequency accuracy between the clock generated by the clock generation unit 153 and the high-precision clock generated by the high-precision clock generation unit 151. However, it is difficult to determine the frequency of the high-precision clock generated by the high-precision clock generation unit 151 by referencing frequencies other than those of the clock generated by the clock generation unit 153. Therefore, simulations are performed in advance under conditions where a spoofing signal is present and where it is not, to identify the possible ranges of frequency stability and frequency accuracy for the high-precision clock generated by the high-precision clock generation unit 151, and these are set as thresholds suitable for spoofing detection. In other words, the determination unit 154 determines that spoofing is occurring if the magnitude of the frequency stability or frequency accuracy of the clock generated by the clock generation unit 153 is greater than a predetermined threshold, and determines that spoofing is not occurring if it is less than the threshold. The determination unit 154 may also dynamically set the threshold. When the determination unit 154 dynamically sets the threshold, as an example, it may measure the frequency stability or frequency accuracy based on the frequency of the clock generated by the clock generation unit 153 within a predetermined period when the high-precision clock generation unit 151 generates a high-precision clock by frequency control, and use the average of this with a threshold predetermined by simulation as the new threshold.

[0031] The determination unit 154 may change the threshold used for determination depending on whether the clock generated by the clock generation unit 153 is a high-precision clock or not. When the threshold used when the clock generated by the clock generation unit 153 is a high-precision clock is set as the first threshold, and the threshold used when the clock generated by the clock generation unit 153 is not a high-precision clock is set as the second threshold, the second threshold may be set to a value greater than the first threshold. The second threshold may also be set to the same value as the first threshold. This is because when the clock generated by the clock generation unit 153 is not a high-precision clock, the positioning error included in the frequency stability and frequency accuracy is large, so it is necessary to set the threshold taking the positioning error into consideration. The determination unit 154 may decide whether to set the threshold as the first threshold or the second threshold based on the information transmitted from the clock generation unit 153 regarding whether the clock generated by the clock generation unit 153 is a high-precision clock or not.

[0032] Figures 3(a) and 3(b) are graphs showing the time evolution of the frequency deviations of the high-precision clock generated by the high-precision clock generation unit 151 and the clock generated by the clock generation unit 153, respectively, under conditions where spoofing is intentionally present and where it is not. In the graphs of Figures 3(a) and 3(b), the vertical axis shows the average frequency deviation of (a) the high-precision clock generated by the high-precision clock generation unit 151 and (b) the clock generated by the clock generation unit 153 by standalone measurement, over a certain period of time going back from the present to the past. More specifically, it represents the average rate of change of 1 PPS over a certain period of time going back from the present to the past. The horizontal axis is the time axis, showing the elapsed time from the start of a week (TOW: Time Of Week). The interval from T1 to T2 is the period during which spoofing is present, and the periods before T1 and after T2 are periods without spoofing.

[0033] Figure 3(a) is an example of a graph showing the average time change of the frequency deviation of the high-precision clock generated by frequency control using MADOCA-PPP in the high-precision clock generation unit 151 over a certain period of time, from the present to the past. The measurement in Figure 3 was performed by measuring the time difference between the 1PPS signal generated by the high-precision clock of the high-precision clock generation unit 151 and the 1PPS of a reference clock with high frequency accuracy and frequency stability using a time interval counter. As shown in Figure 3(a) for the period T1-T2 and other periods, the high-precision clock generation unit 151 performs frequency control using positioning results obtained using the real positioning signal in an environment without spoofing, so the frequency deviation is stably close to 0. On the other hand, in this measurement, during the period T1-T2, spoofing occurred from the spoofer 200, MADOCA-PPP could not be performed, and the high-precision clock of the high-precision clock generation unit 151 transitioned to a free-run state where frequency control could not be performed, resulting in a nearly constant frequency deviation.

[0034] Figure 3(b) is an example of a graph showing the average time variation of the frequency deviation of the clock generated by the clock generation unit 153 by standalone positioning during the measurement in Figure 3(a), over a certain period of time going back from the present to the past. In periods other than T1-T2 in Figure 3(b), when there is no spoofing, the frequency deviation of the clock generated by the clock generation unit 153 is close to 0, and the difference from the frequency deviation of the high-precision clock generation unit 151 in Figure 3(a) is small. The difference in frequency stability is also small. On the other hand, in the period T1-T2, the clock generated by the clock generation unit 153 is generated based on the clock from the spoofer 200, which has lower accuracy and reliability compared to the satellite clock, so the frequency deviation is large, and the difference from the frequency deviation of the high-precision clock generation unit 151 in Figure 3(a) is large. Furthermore, during the T1-T2 period when spoofing is occurring, the accuracy of the spoofer 200's clock is inferior to that of the satellite. As a result, the fluctuation range of the frequency deviation is larger compared to other periods when spoofing is not occurring, and the difference from the frequency stability of the high-precision clock generation unit 151 in Figure 3(a) is large.

[0035] As shown in these graphs, the inventors discovered that the clock generated by the clock generation unit 153 when it is not receiving a signal from the spoofer 200 fluctuates with a frequency accuracy and frequency stability similar to that of the high-precision clock generated by the high-precision clock generation unit 151, while the clock generated by the clock generation unit 153 when it is receiving a signal from the spoofer 200 fluctuates in frequency accuracy and frequency stability by more than a predetermined amount compared to the high-precision clock generated by the high-precision clock generation unit 151. The information processing device 100 according to this embodiment utilizes this to detect the presence or absence of spoofing. As a result of multiple trials, the inventors discovered that, in the high-precision clock generated by the high-precision clock generation unit 151, when it is not subjected to spoofing, the average deviation over the measurement time is 0.0001 ns per second, with a standard deviation of 0.002 ns, and when it is subjected to spoofing, the average deviation over the measurement time is 0.244 ns per second, with a standard deviation of 0.022 ns. Furthermore, it was discovered that, in the clock generated by the clock generation unit 153 by standalone positioning, when spoofing is not present, an average deviation of 0.008 ns per second occurs over the measurement time, with a standard deviation of 0.070 ns. When spoofing is present, an average deviation of 1 PPS (2.321 ns per second) occurs over the measurement time, with a standard deviation of 1.165 ns. As a result, as an example, when detecting spoofing by frequency accuracy, the second threshold may be set to 0.30 ns per second, and when detecting spoofing by frequency stability, the second threshold may be set to a standard deviation of 0.10 ns. However, this is just an example, and these thresholds may be set higher by assuming a larger error in the frequency stability or accuracy of the clock generated by the clock generation unit 153. Considering positioning errors, the first threshold should be set to be smaller than or equal to the second threshold for both frequency accuracy and frequency stability. As an example, the value of the first threshold may be set to the same value as the second threshold.

[0036] If the determination unit 154 detects that spoofing is occurring, it transmits that fact to the output control unit 155.

[0037] When the determination unit 154 determines that spoofing is occurring, the output control unit 155 causes the output unit 130 to output information indicating that spoofing has been detected. This information may be text information indicating that spoofing is occurring, image information indicating that spoofing is occurring, or audio information indicating that spoofing is occurring. This allows the user of the information processing device 100 to recognize that the location information provided by the information processing device 100 may be incorrect.

[0038] <Operation> From here, the operation of the information processing device 100 will be explained with reference to the flowchart shown in Figure 4.

[0039] As shown in Figure 4, the communication unit 110 of the information processing device 100 receives a positioning signal from a positioning satellite (step S401). The communication unit 110 transmits the received positioning signal to the control unit 150.

[0040] The communication unit 110 receives a positioning signal which may include a signal from the spoofer 200 (step S402). The communication unit 110 transmits the positioning signal to the control unit 150, which receives it. The receiving unit 152 transmits the received positioning signal to the high-precision clock generation unit 151 and the clock generation unit 153.

[0041] The high-precision clock generation unit 151 of the control unit 150, in the case of GPS-DO, performs positioning based on the transmitted positioning signal in an environment where no spoofing signal is present, and generates a high-precision clock (step S403).

[0042] The clock generation unit 153 performs positioning based on the positioning signal which may include the signal transmitted from the spoofer, and generates a clock (step S404). This clock may or may not be a high-precision clock.

[0043] The determination unit 154 compares the frequency of the clock generated by the clock generation unit 153 with the frequency of the high-precision clock generated by the high-precision clock generation unit 151 (step S405).

[0044] If the determination unit 154 determines that the difference in frequency deviation or frequency stability within a predetermined period between the clock generated by the clock generation unit 153 and the high-precision clock generated by the high-precision clock generation unit 151 is greater than or equal to a predetermined value (YES in step S405), the receiving unit 152 determines that there is a spoofing signal in the signal it receives, and the output control unit 155 outputs information indicating the presence of a spoofing signal (step S406), and the process ends. On the other hand, if the determination unit 154 determines that the difference in frequency deviation or frequency stability within a predetermined period between the clock generated by the clock generation unit 153 and the high-precision clock generated by the high-precision clock generation unit 151 is less than a predetermined value (NO in step S405), the receiving unit 152 determines that there is no spoofing signal in the signal it receives, and the output control unit 155 outputs information indicating the absence of a spoofing signal (step S407), and the process ends. Note that if there is no spoofing signal, the output of that information may be omitted.

[0045] Although not shown in the flowchart in Figure 4, positioning may, of course, be performed upon reception of the positioning signal. Also, in the flowchart in Figure 4, the processing from step S403 onwards may be executed repeatedly. For example, it may be executed at each positioning epoch. Furthermore, the processing in step S402 may be executed as appropriate (for example, each time the determination unit 154 receives a determination result indicating that there is no spoofing). In addition, if the high-precision clock 151 is GPS-DO, after step S406 or step S407, the determination unit 154 may transmit the determination result to the high-precision clock generation unit 151, and if the determination result from the determination unit 154 is that there is no spoofing, the high-precision clock 151 may perform positioning with the phase difference detector and perform frequency control on the oscillator, and if the determination result is that there is spoofing, it may not perform frequency control on the oscillator.

[0046] <Summary> The information processing device 100 in this embodiment is a device that generates a high-precision clock when it is not being spoofed, and then detects spoofing if the frequency difference between this clock and a clock generated based on a subsequently received signal is greater than or equal to a predetermined value. Unlike the satellite 10, the spoofer 20 is considered to be very unlikely to be equipped with an expensive atomic clock, so the time information contained in the signal transmitted from the spoofer 20 is considered to be less accurate (a discrepancy occurs) compared to an atomic clock. Therefore, a discrepancy occurs between the clock generated by receiving a signal from the spoofer 20 and the high-precision clock generated when no signal is received from the spoofer 20. The information processing device 100 detects this discrepancy and detects that spoofing is occurring.

[0047] <Supplement> The information processing device 100 according to the above embodiment is not limited to the above embodiment, as long as it uses the frequency of a high-precision clock to detect spoofing. Various modifications will be described below.

[0048] (1) In the above embodiment, the information processing device 100 uses the high-precision clock generated by the high-precision clock generation unit 151 when it is not receiving a signal from the spoofer 200 as the high-precision clock. However, the information processing device 100 cannot normally recognize whether or not it is receiving a signal from the spoofer 200 in its initial state. Therefore, the high-precision clock generation unit 151 may receive positioning signals and generate clocks over a predetermined period (for example, one week or one month, but not limited to this period), and within that predetermined period, the clock in the portion where the timing and frequency of the clock best match is used as the high-precision clock (the high-precision clock generated when it is not receiving a signal from the spoofer 200).

[0049] (2) MADOCA as described in the above embodiment may be replaced by a higher-precision positioning technology if such a technology exists.

[0050] (3) In the above embodiment, the information processing device 100 is shown as an example in which it uses a CPU (Central Processing Unit) to determine whether or not it is being spoofed by software. That is, the information processing device 100 includes a CPU that executes instructions for a program which is software that realizes each function, a ROM (Read Only Memory) or storage device (collectively referred to as a "recording medium") on which the program and various data are recorded in a way that can be read by the information processing device (or CPU), a RAM (Random Access Memory) for expanding the program, and so on. The object of the present invention is achieved when the information processing device (or CPU) reads the program from the recording medium and executes it. The program may also be supplied to the information processing device via any transmission medium (such as a communication network or broadcast waves) that can transmit the program. The present invention can also be realized in the form of a data signal embedded in a carrier wave, in which the program is embodied by electronic transmission.

[0051] The above program can be implemented using, for example, scripting languages ​​such as ActionScript and JavaScript®, object-oriented programming languages ​​such as Objective-C and Java®, and markup languages ​​such as HTML5. Furthermore, a system including a mobile terminal (for example, an information processing device 100) equipped with components that realize each of the functions realized by the above program, and a server equipped with components that realize the remaining functions different from the above functions, also falls within the scope of the present invention.

[0052] Furthermore, each functional unit of the control unit 150 may be implemented by logic circuits (hardware) formed on an integrated circuit (IC chip), and in that case, each functional unit may be implemented as a separate circuit, or multiple functional units may be implemented by a single circuit.

[0053] (4) The information processing apparatus 100 according to this embodiment has been described based on various drawings and examples, but it should be noted that those skilled in the art will find it easy to make various modifications and alterations based on this disclosure. Accordingly, it should be noted that these modifications and alterations are within the scope of the present invention. For example, the functions and so on included in each means, each step, etc. can be rearranged in a way that is not logically contradictory, and multiple means and steps, etc. can be combined into one or divided. Furthermore, the configurations shown in the above embodiments may be combined as appropriate. [Explanation of symbols]

[0054] 10a,10b,10c satellite 100 Information Processing Devices 110 Communications Department 120 Input section 130 Output section 140 Storage section 150 Control Unit 151 High-precision clock generation unit 152 Receiving Unit 153 Judgment section 154 Judgment section 155 Output Control Unit 200 Spoofer

Claims

1. A high-precision clock generation unit that generates a high-precision clock based on positioning signals from positioning satellites, A receiving unit that can be used for positioning and receives a positioning signal including time information, The receiving unit generates a clock based on the positioning received, A determination unit compares the frequency of the clock generated by the clock generation unit with the frequency of the high-precision clock generated by the high-precision clock generation unit, and determines whether or not a spoofing signal is present in the positioning signal received by the receiving unit. An information processing device equipped with the following features.

2. The determination unit determines that a spoofing signal exists if there is a difference of a predetermined threshold or more between the magnitude of the frequency accuracy of the clock generated by the clock generation unit and the magnitude of the frequency accuracy of the high-precision clock generated by the high-precision clock generation unit, with respect to the frequency accuracy which represents the average of the frequency deviation of the clock frequency over a certain period. The information processing apparatus according to feature 1.

3. The determination unit changes the threshold depending on whether the clock generated by the clock generation unit is a high-precision clock or not, and makes a determination accordingly. The information processing apparatus according to feature 2.

4. The determination unit further determines whether or not a spoofing signal exists if there is a difference of a predetermined threshold or more between the frequency stability of the clock generated by the clock generation unit and the frequency stability of the high-precision clock generated by the high-precision clock generation unit, which indicates the variation in the clock frequency within a certain period. The information processing apparatus according to feature 2.

5. Computers A high-precision clock generation step that generates a high-precision clock based on positioning signals from positioning satellites, A receiving step that can be used for positioning and receives a positioning signal including time information, The reception step includes a clock generation step that generates a clock based on the received positioning, A determination step that compares the frequency of the clock generated by the clock generation step with the frequency of the high-precision clock generated by the high-precision clock generation step, and determines whether or not a spoofing signal is present in the positioning signal received by the reception step. An information processing method that performs the following.

6. On the computer, A high-precision clock generation function that generates a high-precision clock based on positioning signals from positioning satellites, It can be used for positioning and has a receiving function that receives positioning signals including time information, The aforementioned receiving function generates a clock based on the positioning data received by the receiving function, A determination function that compares the frequency of the clock generated by the clock generation function with the frequency of the high-precision clock generated by the high-precision clock generation function, and determines whether or not a spoofing signal is present in the positioning signal received by the receiving function. An information processing program that makes this possible.

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