Authentication device, authentication method, and program

Abstract

The present invention provides an authentication device, an authentication method, and a program capable of performing authentication according to the individual characteristics of each device. [Solution] The authentication device comprises a stimulus generation unit, an acquisition unit, an analysis unit, and a determination unit. The stimulus generation unit generates stimuli for the constituent devices. The acquisition unit acquires the responses within the devices based on the stimuli generated by the stimulus generation unit. The analysis unit analyzes the responses acquired by the acquisition unit and extracts the characteristics of the responses. The determination unit determines whether authentication is OK or NG based on a master key, which is the characteristic extracted and stored in advance by the analysis unit, and an authentication key, which is the characteristic extracted by the analysis unit during authentication.

Description

Technical Field

[0001] The present disclosure relates to an authentication device, an authentication method, and a program.

Background Art

[0002] As an authentication method in a terminal device or the like, a method of using device-specific code information or a MAC address recorded in an EEPROM or the like as an authentication key is known. EEPROM is an abbreviation for "Electrically Erasable Programmable Read-Only Memory" (electrically erasable, writable, read-only memory). MAC is an abbreviation for "Media Access Control" (media access control). Also, as another authentication method, a method of connecting a dongle to a USB port, a COM port, or the like is known. USB is an abbreviation for "Universal Serial Bus" (universal serial bus). When using these authentication methods, there is a risk that authentication can be performed on other devices by copying information or reusing a dongle or the like.

[0003] Also, a technique for authentication based on sound collected by a sound collection unit provided in a device is known.

[0004] For example, Patent Document 1 describes a technique of an authentication system. Specifically, paragraph 0037 of Patent Document 1 states that "the storage unit 15 stores the portable terminal identification information 151 and the sound collection determination sound pattern information 152." Also, paragraph 0039 of Patent Document 1 states that "the sound collection determination sound pattern information 152 is information representing a pattern of a determination sound for identifying a determination sound collected by the portable terminal 10 from ambient environmental sounds or the like. Here, the determination sound output by the authentication device 20 is a synthesized sound using a specific frequency, and the sound collection determination sound pattern information 152 is, for example, a frequency spectrum obtained by analyzing this synthesized sound." Furthermore, paragraph 0043 of Patent Document 1 states that "the judgment sound measuring means 163 analyzes the sound pattern collected by the sound collection unit 13 over a predetermined period of, for example, about 3 seconds, and if the analyzed sound pattern matches the pattern of the sound collection judgment sound pattern information 152 stored in the storage unit 15, it extracts the sound of the matching portion as a judgment sound, measures its sound pressure level, and passes it to the passage request transmission means 164." Furthermore, paragraph 0044 of Patent Document 1 states, "The passage request transmission means 164 determines whether the sound pressure level of the judgment sound measured by the judgment sound measurement means 163 is above a predetermined threshold, and only if the sound pressure level is above the threshold, it reads the identification information of the mobile terminal identification information 151 stored in the storage unit 15, generates a passage request signal having this identification information, and transmits it to the authentication device 20 via the wireless communication unit 11. The threshold for the sound pressure level is predetermined based on the value of the sound pressure level at which a mobile terminal 10 located within a predetermined range around the door 30 on the front side of the door 30 can collect the judgment sound from the authentication device 20." Note that in the technology described in Patent Document 1, an authentication device is provided in front of the door, and the mobile terminal collects the sound output by the authentication device (as described in paragraph 0023 of Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2019-120017 [Overview of the project] [Problems that the invention aims to solve]

[0006] In the configuration described in Patent Document 1, the sound output by the authentication device is collected by the sound collection unit of the mobile terminal, and a judgment is made based on that sound. With this configuration, it is not possible to perform authentication according to the individual characteristics of each device (mobile terminal).

[0007] The purpose of this disclosure is to provide an authentication device, an authentication method, and a program that solve the above-mentioned problems. [Means for solving the problem]

[0008] An authentication device according to one aspect of the present disclosure comprises: a stimulus generation unit that generates stimuli to constituent devices; an acquisition unit that acquires responses within the devices based on the stimuli generated by the stimulus generation unit; an analysis unit that analyzes the responses acquired by the acquisition unit and extracts characteristics of the responses; and a determination unit that determines whether authentication is OK or NG based on a master key, which is a characteristic of the device that has been previously extracted and stored by the analysis unit, and an authentication key, which is a characteristic of the device that has been extracted by the analysis unit at the time of authentication.

[0009] An authentication method according to one aspect of this disclosure is as follows: a stimulus generation unit generates stimuli for the constituent devices; an acquisition unit acquires the response within the device based on the stimuli generated by the stimulus generation unit; an analysis unit analyzes the response acquired by the acquisition unit and extracts the characteristics of the response; and a determination unit determines whether authentication is OK or NG based on a master key, which is the characteristic that the analysis unit has previously extracted and stored, and an authentication key, which is the characteristic that the analysis unit extracted at the time of authentication.

[0010] A program according to one aspect of this disclosure is a program for causing a computer to function as an authentication device, comprising: a stimulus generation unit that generates stimuli to constituent devices; an acquisition unit that acquires responses within the device based on the stimuli generated by the stimulus generation unit; an analysis unit that analyzes the responses acquired by the acquisition unit and extracts characteristics of the responses; and a determination unit that determines whether authentication is OK or NG based on a master key, which is a characteristic of the device that has been previously extracted and stored by the analysis unit, and an authentication key, which is a characteristic of the device that has been extracted by the analysis unit during authentication. [Effects of the Invention]

[0011] According to the above embodiment, the authentication device can perform authentication according to the characteristics of each individual device. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram illustrating a basic example of the principle by which the authentication device related to this disclosure performs authentication. [Figure 2] This is a block diagram showing the general functional configuration of the authentication device (terminal device) related to this disclosure. [Figure 3] This is a schematic diagram illustrating the basic principles of the authentication related to this disclosure. [Figure 4] This graph illustrates an example of a stimulus generated by the stimulus generation unit related to this disclosure. [Figure 5] This is a schematic diagram showing an example of authentication key generation data related to this disclosure. [Figure 6] This graph shows the frequency distribution of the sound (timing 1, fan PWM percentage is 100%) acquired by the acquisition unit in accordance with the authentication key generation data related to this disclosure. [Figure 7] This graph shows the frequency distribution of the sound (timing 2, fan PWM percentage is 80%) acquired by the acquisition unit in accordance with the authentication key generation data related to this disclosure. [Figure 8] This graph shows the frequency distribution of the sound (timing 3, fan PWM percentage is 60%) acquired by the acquisition unit in accordance with the authentication key generation data related to this disclosure. [Figure 9] This graph shows the frequency distribution of the sound (timing 4, fan PWM percentage 40%) acquired by the acquisition unit in accordance with the authentication key generation data related to this disclosure. [Figure 10] This graph shows the frequency distribution of the sound (timing 5, fan PWM percentage 20%) acquired by the acquisition unit in response to the authentication key generation data related to this disclosure. [Figure 11] This is a schematic diagram showing an example of the sound data used as the basis for analysis by the analysis unit related to this disclosure. [Figure 12] This is a schematic diagram showing an example of the data structure that serves as the authentication master key or terminal authentication key for the target device related to this disclosure. [Figure 13] This is a flowchart (1 / 3) showing the procedure for the authentication device related to this disclosure to generate an authentication master key. [Figure 14] A flowchart (2 / 3) showing the procedure of the process for the authentication device according to the present disclosure to generate an authentication master key. [Figure 15] A flowchart (3 / 3) showing the procedure of the process for the authentication device according to the present disclosure to generate an authentication master key. [Figure 16] A flowchart (1 / 3) showing the procedure of the process for the authentication device according to the present disclosure to generate a terminal authentication key for a target device. [Figure 17] A flowchart (2 / 3) showing the procedure of the process for the authentication device according to the present disclosure to generate a terminal authentication key for a target device. [Figure 18] A flowchart (3 / 3) showing the procedure of the process for the authentication device according to the present disclosure to generate a terminal authentication key for a target device. [Figure 19] A flowchart showing the procedure of the process when the determination unit of the authentication device according to the present disclosure makes a determination for authentication. [Figure 20] A flowchart showing the overall process control flow of the authentication device according to the present disclosure. [Figure 21] A block diagram showing an example of the internal functional configuration of a computer used to implement the authentication device according to the present disclosure. [Figure 22] A block diagram showing the schematic functional configuration of the authentication device (terminal device) according to the present disclosure. [Figure 23] A schematic diagram showing an example (changing the length of the period of 1 timing) of the case where the stimulus generation unit according to the present disclosure changes the generated stimulus according to the device unique identification information. [Figure 24] A schematic diagram showing an example (changing the authentication key generation data) of the case where the stimulus generation unit according to the present disclosure changes the generated stimulus according to the device unique identification information. [Figure 25] A block diagram showing the schematic functional configuration of the authentication device (terminal device) according to the present disclosure. [Figure 26] A block diagram showing the schematic functional configuration of the authentication device (terminal device) according to the present disclosure. [Modes for carrying out the invention]

[0013] Each embodiment will be described below with reference to the drawings. In all drawings, identical or equivalent components are denoted by the same reference numerals, and common descriptions are omitted.

[0014] <First Embodiment> An embodiment of this disclosure will be described below with reference to the figures.

[0015] This embodiment provides an authentication method for terminal devices that makes unauthorized use, such as copying or tampering, difficult. In this embodiment, the sound generated by a cooling fan built into the casing of the terminal device (authentication device) is observed by a microphone or the like, also installed inside the casing. This embodiment utilizes the device's unique acoustic frequency characteristics (features) of the observed sound, which are caused by individual differences in the fan (such as characteristic changes due to the specified PWM rotation speed) and differences in the configuration of built-in components (mounted components and mechanical parts) such as the power supply unit and storage, for authentication. This makes copying and tampering difficult.

[0016] One embodiment is based on the premise of performing authentication to allow specific software to be launched only on a specific device. However, authentication may be performed for other purposes. The terminal device (authentication device) according to the embodiment also has a cooling fan. The cooling fan can be controlled by an arbitrary PWM value. The PWM-controlled fan itself is implemented using existing technology and can control its rotation speed with high precision. In other words, the number of rotations per unit time of the fan can be controlled according to the PWM value (percentage of pulse width). In other words, the sound emitted by the fan can be changed according to the PWM value (percentage of pulse width). The terminal device (authentication device) according to the embodiment acquires the sound generated from the cooling fan in the device's unique acoustic environment and processes its acoustic frequency characteristics.

[0017] In this embodiment, the authentication master key is created by collecting / recording the sound generated by a fan in a specific device using a microphone attached to that device, analyzing it, and converting it into data using the authentication key generation data. In this embodiment, the key is not the absolute value of the sound pressure level of the fan sound generated at each arbitrary PWM value, but rather the difference between the sound pressure level of any other arbitrary PWM value (e.g., 80%, 60%, 40%, 20%) and the PWM value of 100% as a reference. This is to account for individual differences in the sound pressure value generated due to individual differences in fans. The timing of the authentication key generation data and the timing of the authentication master key are made to correspond.

[0018] Furthermore, in this embodiment, the sound generated by a fan in a specific device is collected / recorded using a microphone attached to the specific device, analyzed, and converted into data to be used as the terminal authentication key for the target device. The key is not the absolute value of the sound pressure level of the fan sound data for each arbitrary PWM value, but rather the difference between the sound pressure level of 100% PWM value and each of the other arbitrary PWM values ​​(e.g., 80%, 60%, 40%, 20%). This is to account for individual differences in the sound pressure value generated due to individual differences in fans. The timing of the authentication key generation data and the timing of the terminal authentication key for the target device are made to correspond.

[0019] In this embodiment, the authentication master key and the terminal authentication key of the target device are compared, and if they match, authentication is considered successful.

[0020] Figure 1 is a schematic diagram showing a basic example of the principle by which an authentication device according to one embodiment performs authentication. In this embodiment, the authentication device 1 may be a computer terminal device. Figure 1 is a schematic cross-sectional view showing an example of the arrangement of various components inside the housing of the authentication device 1. The authentication device 1 is composed of a fan 31, a microphone 32, mounted components 51 and 52, and a mechanical component 53. In this example, the display device (e.g., a liquid crystal display panel) and keyboard are located outside the housing and are therefore not shown.

[0021] Fan 31 is a fan provided to cool the inside of the casing of the authentication device 1 (terminal device 1). Fan 31 has blades that rotate using an electric motor. Fan 31 circulates air or other cooling medium (e.g., water) inside the authentication device 1. Fan 31 generates noise when it rotates. The noise generated from fan 31 is caused by friction between the fan blades and their drive components and the air or cooling medium inside the casing when the fan 31 rotates. In addition, noise may be generated from fan 31 due to other factors.

[0022] The microphone 32 is installed, for example, inside the housing of the authentication device 1, and captures sound at that location and converts it into an electrical signal. The sound signal captured by the microphone 32 is processed by a method described later. The microphone 32 itself can be implemented using existing, well-known technologies.

[0023] The mounted components 51 and 52 are components provided for the authentication device 1 to function as a computer terminal device. Mounted components 51 and 52 may be, for example, a CPU board, a memory board, a power supply unit, a hard disk drive (HDD), a solid-state drive (SSD), a network card for communication, a video card for video display, etc. Mounted components 51 and 52 may also be components other than those exemplified herein.

[0024] The mechanical component 53 is a component that enables the authentication device 1 to function as a computer terminal device, and has a mechanical mechanism. Examples of mechanical components 53 include an electric motor for driving the fan 31, or an electric motor for driving the hard disk drive (HDD). Alternatively, the mechanical component 53 may be a screw or the like for fixing components within the casing of the authentication device 1. The mechanical component 53 may also be a component other than those exemplified herein.

[0025] Note that the number of fans 31, the number of mounted components (51, 52), and the number of mechanical components 53 are not limited to the numbers exemplified in the diagram and are arbitrary.

[0026] As shown in Figure 1, the sound generated by the fan 31 travels through the space inside the housing of the authentication device 1, is captured by the microphone 32, and converted into an electrical signal. A portion of the sound generated by the fan 31 reaches the microphone 32 directly without reflection. The remaining portion of the sound generated by the fan 31 is reflected within the housing by the inner surface of the housing itself, mounted components 51 and 52, mechanical components 53, etc., before reaching the microphone 32. The configuration of components arranged inside the authentication device 1 (terminal device 1) is very often different for each individual authentication device 1 (terminal device 1). In other words, when two arbitrary authentication devices 1 (terminal devices 1) are selected, it is very rare for the configuration of components arranged inside the housing to be exactly the same. That is, when two arbitrary authentication devices 1 (terminal devices 1) are selected, the sound generated from the fans of those two devices may be different, and even if the sound generated from the fans of the two devices is very similar, the sound at the stage when it reaches the microphone 32 after being reflected by various components, etc., is likely to be different.

[0027] In other words, the acoustic environment inside the casing of the authentication device 1 (terminal device 1) differs from one individual device to another. This embodiment performs authentication based on these differences in the acoustic environment of each individual authentication device 1 (terminal device 1).

[0028] Furthermore, the authentication device 1 of this embodiment captures a unique response from each individual by varying the stimuli applied to the fan 31, and performs authentication based on the differences in these responses. The functional configuration of the authentication device 1 for this purpose will now be explained with reference to Figure 2.

[0029] Figure 2 is a block diagram illustrating the schematic functional configuration of an authentication device (terminal device). As shown in the figure, an authentication device 1 according to one embodiment comprises an authentication unit 11, a processing control unit 12, a processing unit 13, and a fan 31. The authentication unit 11 also comprises a stimulus generation unit 21, an analysis unit 22, a determination unit 23, and an acquisition unit 33. As described above, the sound generated from the fan 31 passes through an acoustic environment specific to the individual authentication device 1, is captured by a microphone, and acquired by the acquisition unit 33 within the authentication unit 11. This acoustic environment specific to this individual device is called the device-specific environment 39.

[0030] At least some of the functions of the authentication device 1 can be implemented, for example, by a computer and a program. Each functional unit may also have storage means as needed. These storage means may include, for example, variables in the program or memory allocated during program execution. Alternatively, non-volatile storage means such as a magnetic hard disk drive or a solid-state drive (SSD) may be used as needed. Furthermore, at least some of the functions of each functional unit may be implemented as a dedicated electronic or electrical circuit instead of a program.

[0031] The authentication unit 11 performs the authentication process. In other words, the authentication unit 11 determines whether or not the user has the authority to perform the predetermined process. The details of the authentication unit 11's functions will be explained later.

[0032] The processing control unit 12 requests authentication processing from the authentication unit 11 and receives the result from the authentication unit 11. The processing control unit 12 controls the processing unit 13 to perform a predetermined process only if the received authentication result is "Authentication OK" (OK is also written as "okay" or "ok-eh" and indicates approval). The processing control unit 12 controls the processing unit 13 not to perform the predetermined process if the received authentication result is "Authentication NG" (NG is an abbreviation for "no good" and indicates disapproval). Here, "predetermined process" is, for example, the execution of a specific application program. In other words, the processing control unit 12 controls whether or not the processing unit 13 can execute a specific application program based on the authentication result from the authentication unit 11.

[0033] The processing unit 13 performs some kind of processing. However, when the processing unit 13 performs a specific process (for example, executing a specific application program), it first requests authentication from the processing control unit 12 and follows the control of the processing control unit 12 according to the authentication result. In other words, the processing unit 13 may be a means for running an application program (arithmetic unit and memory, etc.). That is, if authentication is OK, the processing unit 13 executes the specific process. Also, if authentication is NG, the processing unit 13 cannot execute the specific process.

[0034] For example, a specific application program might be written to request authentication before performing its actual processing. The application program might then only proceed with its actual processing if authentication is successful. In other words, whether or not the application program performs its actual processing depends on the authentication result.

[0035] In other words, the processing control unit 12 controls the system to run a specific application program on the processing unit 13 if the determination unit 23 of the authentication unit 11 determines that authentication is OK. The processing control unit 12 controls the system not to run the specific application program on the processing unit 13 if the determination unit 23 of the authentication unit 11 determines that authentication is NG.

[0036] As described above, the fan 31 circulates air or other cooling medium to cool the inside of the housing of the authentication device 1. Noise is generated when the fan 31 is operating. The fan 31 rotates its blades using electricity. In this embodiment, the fan 31 is driven by a predetermined pattern of electricity supplied from the stimulus generation unit 21, which will be described later. The fan 31 is an example of a component that makes up the authentication device 1.

[0037] The device-specific environment 39 is the environment in which the sound generated by the fan 31 is captured by the microphone. Specifically, it is the acoustic environment. As mentioned above, the device-specific environment 39 is the acoustic environment unique to each individual authentication device 1.

[0038] The functions of each part within the authentication unit 11 are as follows:

[0039] The stimulus generation unit 21 generates stimuli for the fan 31 and the device-specific environment 39. The fan 31 is one of the components of the authentication device 1. In other words, the stimulus generation unit 21 generates stimuli to be applied to the component components. Specifically, the stimulus generation unit 21 drives the fan 31 by supplying it with power having a specific pattern. That is, the stimulus is, for example, a pattern of power that drives the fan 31. An example of the specific pattern of power generated by the stimulus generation unit 21 is power that is pulse-width modulated (PWM) in the time direction. A specific example of pulse-width modulation will be explained later with reference to another drawing. Specifically, the stimulus generation unit 21 generates a voltage signal to control (instruct) the rotation speed of the fan 31.

[0040] The stimulus generation unit 21 may generate the power pattern based on the given authentication key generation data. For example, the authentication key generation data may be a series of numbers representing pulse widths for predetermined periods. The power pattern generated by the stimulus generation unit 21 to drive the fan may be power that is pulse-width modulated by a predetermined pulse width.

[0041] The acquisition unit 33 acquires the electrical signal of sound captured by the microphone 32. The acquisition unit 33 acquires the sound signal as a time series of numerical values ​​of sound pressure levels sampled at a sufficiently high sampling frequency. The sound acquired by the acquisition unit 33 is sound generated in the fan 31 and obtained after passing through the device-specific environment 39. In other words, the acquisition unit 33 acquires the response of the fan 31 (component) and the device-specific environment within the device based on the stimulus generated by the stimulus generation unit 21. In other words, the response to the stimulus may be, for example, sound emitted from the fan 31 and acquired after passing through the device-specific environment, which is the environment unique to the authentication device 1.

[0042] The analysis unit 22 analyzes the sound data acquired by the acquisition unit 33 and extracts the characteristics of the response acquired by the acquisition unit 33. Specifically, the analysis unit 22 acquires, for example, numerical values ​​representing the sound pressure level for each frequency component of the sound. The sound pressure level for each frequency component is obtained, for example, by performing a fast Fourier transform on the sound wave signal. The analysis unit 22 generates and stores a master key (authentication master key) in advance. The analysis unit 22 also generates an authentication key (terminal authentication key for the target device) during authentication.

[0043] The determination unit 23 determines whether authentication is OK or NG based on the analysis results (response characteristics) from the analysis unit 22. Specifically, the determination unit 23 compares the master key (authentication master key), which is a characteristic previously extracted and stored by the analysis unit 22, with the authentication key (terminal authentication key of the target device), which is a characteristic extracted by the analysis unit 22 during authentication, and determines whether authentication is OK or NG based on these. The procedure for the determination process by the determination unit 23 will be explained later with reference to the flowchart.

[0044] Figure 3 is a schematic diagram illustrating the basic principle of authentication according to an embodiment. As shown in the figure, in the embodiment, a stimulus is applied to the component device 30. In response to this stimulus, the component device 30 produces a predetermined output. This output can be observed as a response through the device-specific environment 39, which is an environment unique to the device. The component device 30 is, for example, a part of the authentication device 1, and may specifically be a fan 31, etc. The component device 30 may be, for example, a sound corresponding to the stimulus. The device-specific environment 39 may be, for example, an acoustic environment that transmits and reflects sound. The stimulus may be, for example, a pattern of driving power supplied by the stimulus generation unit 21. If the response corresponding to the stimulus is, for example, a sound, it can be captured by a microphone and acquired as data by the acquisition unit 33. Here, the relationship between the stimulus applied to the component device 30 and the responses generated from the component device 30 and the device-specific environment 39 can be considered unique to each individual device, and authentication can be performed using this relationship.

[0045] Figure 4 is a graph illustrating an example of a stimulus generated by the stimulus generation unit 21. The horizontal axis of the figure represents time, and the vertical axis represents voltage (unit: volts (V)). In the illustrated example, the stimulus generation unit 21 supplies a pulse-width modulated voltage signal (power) to drive the fan 31. As shown in the figure, the voltage signal for driving the fan 31 has periodicity. The lower limit of the voltage in a pulse is α1 [V], and the upper limit is α2 [V]. Note that α1 = 0. When the length of one pulse period is 100%, the voltage is α2 for x% of the period. The voltage is α1 for the remaining period of the period. As will be described later, the stimulus generation unit 21 changes the voltage signal to the fan 31 by changing x, for example, x = 100, 80, 60, 40, 20, etc. The stimulation generation unit 21 can supply power. By changing the value of x in this way, the stimulation generation unit 21 provides different stimuli to the fan 31. Changing the percentage value of the PWM when the stimulation generation unit 21 drives the fan 31 changes the sound pressure level and frequency distribution of the sound generated by the fan 31. The length of one cycle is determined based on the specifications of the fan 31. In other words, the PWM frequency is determined based on the specifications of the fan 31. For example, the PWM frequency for DC (direct current) fans used in personal computers and server computers is 25 kHz. The voltage signal supplied by the stimulation generation unit 21 determines the power pattern from the stimulation generation unit 21 to the fan 31.

[0046] Figure 5 is a schematic diagram showing an example of authentication key generation data. As shown in the diagram, the authentication key generation data represents the relationship between timing and the percentage of PWM at that timing (the value of x in Figure 4). In the example of authentication key generation data shown, at timing "1", the percentage of PWM is 100%, at timing "2", the percentage of PWM is 80%, at timing "3", the percentage of PWM is 60%, at timing "4", the percentage of PWM is 40%, and at timing "5", the percentage of PWM is 20%. The meaning of the example of authentication key generation data in Figure 5 is as follows: First, at timing "1", which is a predetermined period of length, the stimulus generation unit 21 supplies power to the fan 31 with a pattern in which the percentage of PWM is 100%. Next, at timing "2", which is a predetermined period of length, the stimulus generation unit 21 supplies power to the fan 31 with a pattern where the PWM percentage is 80%. Next, at timing "3", which is a predetermined period of length, the stimulus generation unit 21 supplies power to the fan 31 with a pattern where the PWM percentage is 60%. Next, at timing "4", which is a predetermined period of length, the stimulus generation unit 21 supplies power to the fan 31 with a pattern where the PWM percentage is 40%. Next, at timing "5", which is a predetermined period of length, the stimulus generation unit 21 supplies power to the fan 31 with a pattern where the PWM percentage is 20%. In other words, this authentication key generation data represents the relationship between the timing and the PWM value (percentage) for driving the fan 31 in the authentication device 1. Note that in this example, the length of each period from timing "1" to "5" may be the same (for example, 2 seconds).

[0047] The authentication key generation data shown in Figure 5 is merely an example. The relationship between timing and PWM percentage values ​​may differ from the example shown in Figure 5. Furthermore, the duration of each timing period does not necessarily have to be the same.

[0048] Based on the authentication key generation data shown in Figure 5, the stimulus generation unit 21 generates power patterns (percentage PWM power patterns based on the authentication key generation data) for each of the multiple periods (each of the periods from timing "1" to "5"). The acquisition unit 33 acquires the sound, which is the response to the stimulus, for each of these periods. When the analysis unit 22 analyzes the sound response, for example, it extracts the result of subtracting the sound pressure level for each frequency in a second period (any of the periods from timing "1" to "5" above, but at a different timing than the first period) from the sound pressure level for each frequency in the first period (any of the periods from timing "1" to "5" above) as the aforementioned feature. An example of this subtraction result will be explained later with reference to Figure 12.

[0049] Figures 6 to 10 are graphs showing the frequency distribution of sound acquired by the acquisition unit 33 in correspondence with the authentication key generation data exemplified in Figure 5. In each of Figures 6 to 10, the horizontal axis is frequency (unit: Hertz (Hz)) and the vertical axis is sound pressure level (unit: decibel (dB)). Figure 6 shows the frequency distribution of sound acquired by the acquisition unit 33 in correspondence with timing "1" (percentage of PWM of fan 31 is 100%). Figure 7 shows the frequency distribution of sound acquired by the acquisition unit 33 in correspondence with timing "2" (percentage of PWM of fan 31 is 80%). Figure 8 shows the frequency distribution of sound acquired by the acquisition unit 33 in correspondence with timing "3" (percentage of PWM of fan 31 is 60%). Figure 9 shows the frequency distribution of sound acquired by the acquisition unit 33 in correspondence with timing "4" (percentage of PWM of fan 31 is 40%). Figure 10 shows the frequency distribution of the sound acquired by the acquisition unit 33 in accordance with the timing "5" (where the percentage of PWM of the fan 31 is 20%).

[0050] The acquisition unit 33 can obtain frequency-specific sound pressure level data by performing a Fourier transform on the acquired sound signal. The analysis unit 22 can obtain sound pressure level values ​​at specific frequencies based on the data shown in Figures 6 to 10.

[0051] Figure 11 is a schematic diagram showing an example of generated sound data that the analysis unit 22 uses as the basis for analysis. In other words, the generated sound data is data representing sounds of different frequencies acquired by the acquisition unit 33. As shown in the figure, the generated sound data represents the sound pressure level (in decibels) for each frequency at each of the timings "1" to "5". The data in the example shown represents the sound pressure levels at frequencies of 30 Hz, 1 kHz, and 10 kHz. Note that k stands for kilo, and represents 1000. As shown in the figure, at each of the timings "1" to "5", the sound pressure levels at frequency 30 Hz are 10, 8, 7, 4, and 2 [dB]. Also, the sound pressure levels at frequency 1 kHz are 10, 9, 6, 3, and 1 [dB]. Also, the sound pressure levels at frequency 10 kHz are 10, 7, 5, 2, and 1 [dB].

[0052] The analysis unit 22 acquires the sound generated as shown in Figure 11, both when the authentication master key is generated and when the terminal authentication key for the target device is generated.

[0053] Figure 12 is a schematic diagram showing an example of the data structure for the authentication master key or the terminal authentication key of the target device. The analysis unit 22 generates data with the structure shown in Figure 12 by calculating the difference in sound pressure levels between timings based on the generated sound data (Figure 11) when generating the authentication master key and when generating the terminal authentication key of the target device. As shown in the figure, the data for the authentication master key or the terminal authentication key of the target device has values ​​for each frequency, such as the difference in sound pressure levels between timings "1" and "2" (column A), the difference in sound pressure levels between timings "1" and "3" (column B), the difference in sound pressure levels between timings "1" and "4" (column C), and the difference in sound pressure levels between timings "1" and "5" (column D). The data in the first row of the figure represents the sound pressure level difference at a frequency of 30 Hz. The data in the second row represents the sound pressure level difference at a frequency of 1 kHz. The data in the third row represents the sound pressure level difference at a frequency of 10 kHz.

[0054] The data shown in the diagram represents the characteristics of the response (sound) to the stimuli of the authentication device 1. In other words, when the analysis unit 22 analyzes the sound, which is the response to the stimuli, it extracts the characteristics of the response by performing an analysis based on the sound pressure level for each frequency of the sound. In addition, the analysis unit 22 may perform the analysis on the frequencies of one or more samples. In the example shown in Figure 12, the frequencies of the sound samples are 30 Hz, 1 kHz, and 10 kHz. In other words, when the analysis unit 22 analyzes the sound, which is the response, it may extract the characteristics of the response by performing an analysis based on the sound pressure level of one or more samples.

[0055] As illustrated in Figure 12, the analysis unit 22, for example, when analyzing a sound response, extracts the result of subtracting the sound pressure level for each frequency in a second period (any of the periods from timings "1" to "5" above, but at a different timing than the first period) from the sound pressure level for each frequency in a first period (any of the periods from timings "1" to "5" above) as the aforementioned feature.

[0056] Next, the processing procedure in authentication device 1 will be explained with reference to the flowchart.

[0057] Figures 13 to 15 are flowcharts showing the procedure for the authentication device 1 to generate an authentication master key. The following explanation will follow these flowcharts.

[0058] First, in step S1 in Figure 13, the stimulus generation unit 21 refers to the authentication key generation data and starts controlling the fan 31 accordingly. In the following steps S2 to S11, the timing changes from 1, 2, 3, 4, and 5. In other words, the stimulus generation unit 21 changes the PWM percentage value at each timing according to the authentication key generation data as illustrated in Figure 5.

[0059] Next, in step S2, the stimulus generation unit 21 controls the timing "1". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the PWM percentage value becomes 100%.

[0060] Next, in step S3, the authentication device 1 performs sound collection, recording, and recording at timing "1". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at a frequency of 30 Hz as T1-M30. The acquisition unit 33 records the sound pressure level at a frequency of 1 kHz as T1-M1k. The acquisition unit 33 records the sound pressure level at a frequency of 10 kHz as T1-M10k.

[0061] Next, in step S4, the stimulus generation unit 21 controls the timing "2". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 80%.

[0062] Next, in step S5, the authentication device 1 performs sound collection, recording, and recording at timing "2". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at a frequency of 30 Hz as T2-M30. The acquisition unit 33 records the sound pressure level at a frequency of 1 kHz as T2-M1k. The acquisition unit 33 records the sound pressure level at a frequency of 10 kHz as T2-M10k.

[0063] Next, in step S6, the stimulus generation unit 21 controls the timing "3". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 60%.

[0064] Next, in step S7, the authentication device 1 performs sound collection, recording, and recording at timing "3". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at a frequency of 30 Hz as T3-M30. The acquisition unit 33 records the sound pressure level at a frequency of 1 kHz as T3-M1k. The acquisition unit 33 records the sound pressure level at a frequency of 10 kHz as T3-M10k.

[0065] Moving on to Figure 14, in step S8, the stimulus generation unit 21 controls the timing "4". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 40%.

[0066] Next, in step S9, the authentication device 1 performs sound collection, recording, and recording at timing "4". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at a frequency of 30 Hz as T4-M30. The acquisition unit 33 records the sound pressure level at a frequency of 1 kHz as T4-M1k. The acquisition unit 33 records the sound pressure level at a frequency of 10 kHz as T4-M10k.

[0067] Next, in step S10, the stimulus generation unit 21 controls the timing "5". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 20%.

[0068] Next, in step S11, the authentication device 1 performs sound collection, recording, and recording at timing "5". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at a frequency of 30 Hz as T5-M30. The acquisition unit 33 records the sound pressure level at a frequency of 1 kHz as T5-M1k. The acquisition unit 33 records the sound pressure level at a frequency of 10 kHz as T5-M10k.

[0069] Moving on to Figure 15, in step S12, the analysis unit 22 generates an authentication master key through calculation. That is, the analysis unit 22 performs the following calculation using the data obtained up to step S11.

[0070] The analysis unit 22 calculates the difference MK1-2_30 between timing 1 and timing 2 of the sound pressure level at a frequency of 30 Hz using the following formula. MK1-2_30=(T1-M30)-(T2-M30)

[0071] Furthermore, the analysis unit 22 calculates the difference MK1-2_1k between timing 1 and timing 2 of the sound pressure level at a frequency of 1 kHz using the following formula. MK1-2_1k=(T1-M1k)-(T2-M1k)

[0072] Furthermore, the analysis unit 22 calculates the difference MK1-2_10k between timing 1 and timing 2 of the sound pressure level at a frequency of 10 kHz using the following formula. MK1-2_10k=(T1-M10k)-(T2-M10k)

[0073] Furthermore, the analysis unit 22 calculates the difference MK1-3_30 between timing 1 and timing 3 of the sound pressure level at a frequency of 30 Hz using the following formula. MK1-3_30=(T1-M30)-(T3-M30)

[0074] Furthermore, the analysis unit 22 calculates the difference MK1-3_1k between timing 1 and timing 3 of the sound pressure level at a frequency of 1 kHz using the following formula. MK1-3_1k=(T1-M1k)-(T3-M1k)

[0075] Furthermore, the analysis unit 22 calculates the difference MK1-3_10k between timing 1 and timing 3 of the sound pressure level at a frequency of 10 kHz using the following formula. MK1-3_10k=(T1-M10k)-(T3-M10k)

[0076] Furthermore, the analysis unit 22 calculates the difference MK1-4_30 between timing 1 and timing 4 of the sound pressure level at a frequency of 30 Hz using the following formula. MK1-4_30=(T1-M30)-(T4-M30)

[0077] Furthermore, the analysis unit 22 calculates the difference MK1-4_1k between timing 1 and timing 4 of the sound pressure level at a frequency of 1 kHz using the following formula. MK1-4_1k=(T1-M1k)-(T4-M1k)

[0078] Furthermore, the analysis unit 22 calculates the difference MK1-4_10k between timing 1 and timing 4 of the sound pressure level at a frequency of 10 kHz using the following formula. MK1-4_10k=(T1-M10k)-(T4-M10k)

[0079] Furthermore, the analysis unit 22 calculates the difference MK1-5_30 between timing 1 and timing 5 of the sound pressure level at a frequency of 30 Hz using the following formula. MK1-5_30=(T1-M30)-(T5-M30)

[0080] Furthermore, the analysis unit 22 calculates the difference MK1-5_1k between timing 1 and timing 5 of the sound pressure level at a frequency of 1 kHz using the following formula. MK1-5_1k=(T1-M1k)-(T5-M1k)

[0081] Furthermore, the analysis unit 22 calculates the difference MK1-5_10k between timing 1 and timing 5 of the sound pressure level at a frequency of 10 kHz using the following formula. MK1-5_10k=(T1-M10k)-(T5-M10k)

[0082] As explained above in Figures 13 to 15, an authentication master key is generated. The authentication master key consists of the following data columns. MK1-2_30, MK1-2_1k, MK1-2_10k, MK1-3_30, MK1-3_1k, MK1-3_10k, MK1-4_30, MK1-4_1k, MK1-4_10k, MK1-5_30, MK1-5_1k, MK1-5_10k

[0083] Figures 16 to 18 are flowcharts showing the procedure for the authentication device 1 to generate a terminal authentication key for the target device. The following explanation will follow these flowcharts.

[0084] First, in step S101 in Figure 16, the stimulus generation unit 21 refers to the authentication key generation data and starts controlling the fan 31 accordingly. In the following steps S102 to S111, the timing changes to 1, 2, 3, 4, and 5. In other words, the stimulus generation unit 21 changes the PWM percentage value at each timing according to the authentication key generation data as illustrated in Figure 5.

[0085] Next, in step S102, the stimulus generation unit 21 controls the timing "1". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the PWM percentage value becomes 100%.

[0086] Next, in step S103, the authentication device 1 performs sound collection, recording, and recording at timing "1". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at frequency 30 Hz as T1-T30. The acquisition unit 33 records the sound pressure level at frequency 1 kHz as T1-T1k. The acquisition unit 33 records the sound pressure level at frequency 10 kHz as T1-T10k.

[0087] Next, in step S104, the stimulus generation unit 21 controls the timing "2". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 80%.

[0088] Next, in step S105, the authentication device 1 performs sound collection, recording, and recording at timing "2". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at frequency 30 Hz as T2-T30. The acquisition unit 33 records the sound pressure level at frequency 1 kHz as T2-T1k. The acquisition unit 33 records the sound pressure level at frequency 10 kHz as T2-T10k.

[0089] Next, in step S106, the stimulus generation unit 21 controls the timing "3". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 60%.

[0090] Next, in step S107, the authentication device 1 performs sound collection, recording, and recording at timing "3". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at frequency 30 Hz as T3-T30. The acquisition unit 33 records the sound pressure level at frequency 1 kHz as T3-T1k. The acquisition unit 33 records the sound pressure level at frequency 10 kHz as T3-T10k.

[0091] Moving on to Figure 17, in step S108, the stimulus generation unit 21 controls the timing "4". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 40%.

[0092] Next, in step S109, the authentication device 1 performs sound collection, recording, and recording at timing "4". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at frequency 30 Hz as T4-T30. The acquisition unit 33 records the sound pressure level at frequency 1 kHz as T4-T1k. The acquisition unit 33 records the sound pressure level at frequency 10 kHz as T4-T10k.

[0093] Next, in step S110, the stimulus generation unit 21 controls the timing "5". In other words, the stimulus generation unit 21 controls the drive power of the fan 31 so that the percentage value of the PWM becomes 20%.

[0094] Next, in step S111, the authentication device 1 performs sound collection, recording, and recording at timing "5". That is, the acquisition unit 33 records the sound pressure level at each frequency. Specifically, the acquisition unit 33 records the sound pressure level at frequency 30 Hz as T5-T30. The acquisition unit 33 records the sound pressure level at frequency 1 kHz as T5-T1k. The acquisition unit 33 records the sound pressure level at frequency 10 kHz as T5-T10k.

[0095] Moving on to Figure 18, in step S112, the analysis unit 22 generates a terminal authentication key through calculation. That is, the analysis unit 22 performs the following calculation using the data acquired up to step S111.

[0096] The analysis unit 22 calculates the difference SK1-2_30 between timing 1 and timing 2 of the sound pressure level at a frequency of 30 Hz using the following formula. SK1-2_30=(T1-T30)-(T2-T30)

[0097] Furthermore, the analysis unit 22 calculates the difference SK1-2_1k between timing 1 and timing 2 of the sound pressure level at a frequency of 1 kHz using the following formula. SK1-2_1k=(T1-T1k)-(T2-T1k)

[0098] Furthermore, the analysis unit 22 calculates the difference SK1-2_10k between timing 1 and timing 2 of the sound pressure level at a frequency of 10 kHz using the following formula. SK1-2_10k=(T1-T10k)-(T2-T10k)

[0099] Furthermore, the analysis unit 22 calculates the difference SK1-3_30 between timing 1 and timing 3 of the sound pressure level at a frequency of 30 Hz using the following formula. SK1-3_30=(T1-T30)-(T3-T30)

[0100] Furthermore, the analysis unit 22 calculates the difference SK1-3_1k between timing 1 and timing 3 of the sound pressure level at a frequency of 1 kHz using the following formula. SK1-3_1k=(T1-T1k)-(T3-T1k)

[0101] Furthermore, the analysis unit 22 calculates the difference SK1-3_10k between timing 1 and timing 3 of the sound pressure level at a frequency of 10 kHz using the following formula. SK1-3_10k=(T1-T10k)-(T3-T10k)

[0102] Furthermore, the analysis unit 22 calculates the difference SK1-4_30 between timing 1 and timing 4 of the sound pressure level at a frequency of 30 Hz using the following formula. SK1-4_30=(T1-T30)-(T4-T30)

[0103] Furthermore, the analysis unit 22 calculates the difference SK1-4_1k between timing 1 and timing 4 of the sound pressure level at a frequency of 1 kHz using the following formula. SK1-4_1k=(T1-T1k)-(T4-T1k)

[0104] Furthermore, the analysis unit 22 calculates the difference SK1-4_10k between timing 1 and timing 4 of the sound pressure level at a frequency of 10 kHz using the following formula. SK1-4_10k=(T1-T10k)-(T4-T10k)

[0105] Furthermore, the analysis unit 22 calculates the difference SK1-5_30 between timing 1 and timing 5 of the sound pressure level at a frequency of 30 Hz using the following formula. SK1-5_30=(T1-T30)-(T5-T30)

[0106] Furthermore, the analysis unit 22 calculates the difference SK1-5_1k between timing 1 and timing 5 of the sound pressure level at a frequency of 1 kHz using the following formula. SK1-5_1k=(T1-T1k)-(T5-T1k)

[0107] Furthermore, the analysis unit 22 calculates the difference SK1-5_10k between timing 1 and timing 5 of the sound pressure level at a frequency of 10kHz using the following formula. SK1-5_10k=(T1-T10k)-(T5-T10k)

[0108] As explained above in Figures 16 to 18, a device authentication key is generated. The device authentication key consists of the following data columns. SK1-2_30, SK1-2_1k, SK1-2_10k, SK1-3_30, SK1-3_1k, SK1-3_10k, SK1-4_30, SK1-4_1k, SK1-4_10k, SK1-5_30, SK1-5_1k, SK1-5_10k

[0109] Figure 19 is a flowchart showing the procedure for the determination unit 23 of the authentication device 1 when it makes a determination for authentication. The determination unit 23 performs authentication by comparing the authentication master key and the terminal authentication key.

[0110] In this flowchart, a comparison of differences in sound pressure levels is performed, but a predetermined amount of error may be allowed. That is, for example, in step S201, when determining whether "MK1-2_30=SK1-2_30" is true or not, a predetermined error δ (>0) may be introduced to allow for this error. In that case, instead of determining whether "MK1-2_30=SK1-2_30" is true or not, the determination will be whether "(SK1-2_30)-δ≦MK1-2_30≦(SK1-2_30)+δ" is true or not. The same applies to other comparisons from steps S201 to S204.

[0111] In step S201, the determination unit 23 compares the authentication master key and the terminal authentication key with respect to the difference between timing "1" and timing "2". In other words, the determination unit 23, MK1-2_30=SK1-2_30 and MK1-2_1k=SK1-2_1k and MK1-2_10k=SK1-2_10k Determine whether the condition is true or false. If the condition is true, proceed to the next step S202. If the condition is false, jump to step S206.

[0112] In step S202, the determination unit 23 compares the authentication master key and the terminal authentication key with respect to the difference between timing "1" and timing "3". In other words, the determination unit 23, MK1-3_30=SK1-3_30 and MK1-3_1k=SK1-3_1k and MK1-3_10k=SK1-3_10k Determine whether or not this condition is true. If the result of the determination is true, proceed to the next step S203. If the condition is false, jump to step S206.

[0113] In step S203, the determination unit 23 compares the authentication master key and the terminal authentication key with respect to the difference between timing "1" and timing "4". In other words, the determination unit 23, MK1-4_30=SK1-4_30 and MK1-4_1k=SK1-4_1k and MK1-4_10k=SK1-4_10k Determine whether or not this condition is true. If the result of the determination is true, proceed to the next step S204. If the condition is false, jump to step S206.

[0114] In step S204, the determination unit 23 compares the authentication master key and the terminal authentication key with respect to the difference between timing "1" and timing "5". In other words, the determination unit 23 MK1-5_30=SK1-5_30 and MK1-5_1k=SK1-5_1k and MK1-5_10k=SK1-5_10k Determine whether or not this condition is true. If the result of the determination is true, proceed to step S205. If the condition is false, proceed to step S206.

[0115] If the process proceeds to step S205, the determination unit 23 determines that "authentication OK" and terminates the processing of this flowchart.

[0116] If the process proceeds to step S206, the determination unit 23 determines that "authentication failed" and terminates the processing of this flowchart.

[0117] Figure 20 is a flowchart showing the overall control flow of the authentication device according to the embodiment. The following explanation will follow this flowchart.

[0118] In step S301, the authentication device 1 branches based on the operating mode. There are two operating modes: a mode for generating an authentication master key and a mode for performing authentication based on an already generated authentication master key. If the authentication master key generation mode is selected, the process proceeds to step S302. If the authentication execution mode is selected, the process proceeds to step S305.

[0119] Steps S302 and beyond are executed only in the case of authentication master key generation mode. In this case, in step S302, the authentication device 1 determines whether or not it has privileges. Here, privileges are the rights required to execute the authentication master key generation mode. If privileges are found, the process proceeds to the next step S303. If privileges are not found, the authentication master key generation process is not performed, and the process of this flowchart is terminated.

[0120] Next, in step S303, the authentication device 1 generates an authentication master key. The procedure for generating the authentication master key has already been explained with reference to another flowchart.

[0121] Next, in step S304, the authentication device 1 stores the authentication master key generated in step S303. The authentication master key is written to, for example, a semiconductor memory or a magnetic hard disk. When the processing of this step is completed, the entire flowchart is terminated.

[0122] Steps S305 and beyond are executed only in the authentication execution mode. In step S305, the authentication device 1 generates a terminal authentication key. The procedure for generating the terminal authentication key has already been explained with reference to another flowchart.

[0123] Next, in step S306, the authentication device 1 refers to the authentication master key that has already been stored.

[0124] Next, in step S307, the authentication device 1 performs a determination process for authentication using the authentication master key and terminal authentication key mentioned above. The procedure for this determination process has already been explained with reference to another flowchart. Once the processing of this step is completed, the entire flowchart is terminated.

[0125] Figure 21 is a block diagram illustrating an example of the internal functional configuration of a computer used to implement authentication device 1. As shown in the diagram, the computer consists of a central processing unit 901, RAM 902, input / output ports 903, input / output devices 904 and 905, etc., and a bus 906. The computer itself can be implemented using existing technology. The central processing unit 901 executes instructions contained in programs read from RAM 902, etc. The central processing unit 901 writes data to RAM 902, reads data from RAM 902, and performs arithmetic and logical operations according to each instruction. RAM 902 stores data and programs. Each element contained in RAM 902 has an address and can be accessed using that address. RAM stands for "Random Access Memory". Input / output ports 903 are ports for the central processing unit 901 to exchange data with external input / output devices, etc. Input / output devices 904 and 905 exchange data with the central processing unit 901 via input / output ports 903. Bus 906 is a common communication channel used within the computer. For example, the central processing unit 901 reads and writes data to RAM 902 via bus 906. Also, for example, the central processing unit 901 accesses input / output port 903 via bus 906.

[0126] At least some of the functions of the authentication device 1 in the above-described embodiment can be realized by a computer and a program. In this case, the program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed. Here, "computer system" includes hardware such as the OS and peripheral devices. Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, magneto-optical disks, ROMs, CD-ROMs, DVD-ROMs, USB memory, and storage devices such as hard disks built into a computer system. In other words, "computer-readable recording medium" may be a non-transitory computer-readable recording medium. Moreover, "computer-readable recording medium" may also include those that temporarily and dynamically hold programs, such as communication lines when transmitting programs via networks such as the Internet or communication lines such as telephone lines, and those that hold programs for a certain period of time, such as volatile memory inside a computer system that acts as a server or client in such a case. Furthermore, the above-mentioned program may be for realizing some of the functions described above, and may also be able to realize the above-mentioned functions in combination with a program already recorded in the computer system.

[0127] The computer program is, for example, as follows: a program to make a computer function as an authentication device comprising: a stimulus generation unit that generates stimuli to the constituent devices; an acquisition unit that acquires the response within the device based on the stimuli generated by the stimulus generation unit; an analysis unit that analyzes the response acquired by the acquisition unit and extracts the characteristics of the response; and a determination unit that determines whether authentication is OK or NG based on a master key, which is the characteristic that the analysis unit has previously extracted and stored, and an authentication key, which is the characteristic that the analysis unit has extracted at the time of authentication. The processing of each of these units is executed in the computer's arithmetic unit. Here, the stimulus generation unit (21) may, for example, determine an output waveform and control the power supply source according to that waveform. Power from the waveform generated by the stimulus generation unit (21) is supplied to the device. The acquisition unit (33) may, for example, acquire data of an audio signal collected by a microphone or the like.

[0128] As described above, this embodiment realizes an authentication device and authentication method for allowing specific software (application program) to be launched only on a specific device (individual). In this embodiment, the specific device (individual) uses authentication key generation data to control the PWM of a fan, and the resulting sound is collected by a microphone, recorded, and converted into data. Authentication is then performed by comparing the authentication master key and the terminal authentication key.

[0129] In this embodiment, based on an example of authentication key generation data, the PWM percentage was set to 100% at timing "1", 80% at timing "2", 60% at timing "3", 40% at timing "4", and 20% at timing "5". Using timing "1" as a reference, the difference between the sound pressure level at each frequency for timings "2", "3", "4", and "5" and the reference sound pressure level was calculated. This difference value represents the device's unique characteristics.

[0130] [Regarding variations] In the above embodiment, the frequencies used to determine the sound pressure level were 30 Hz, 1 kHz, and 10 kHz. In other words, when analyzing sound, the analysis unit 22 extracts response characteristics by performing an analysis based on the sound pressure level of one or more samples at different frequencies. It is also possible to obtain sound pressure levels using frequencies other than those listed above as samples.

[0131] In the above embodiment, the five PWM values ​​(percentages) in the authentication key generation data were set to 100%, 80%, 60%, 40%, and 20%. Alternatively, the fan 31 may be driven using percentage values ​​other than these. Specific percentage values ​​may be determined as appropriate.

[0132] In the above embodiment, the authentication key generation data is assumed to have 5 PWM values ​​(percentages). That is, the number of timings (periods) is set to 5. However, a different number of timings (periods) may be used. The number of timings (periods) may be any positive integer, for example.

[0133] According to this embodiment, the authentication device 1 returns a response specific to the individual based on the stimulus generated by the stimulus generation unit 21. The analysis unit 22 analyzes this response, enabling authentication based on information specific to that individual.

[0134] <Second Embodiment> Hereinafter, an embodiment relating to this disclosure will be described with reference to the figures. Note that some matters already described in the previous embodiment may be omitted below. Here, we will focus on matters specific to this embodiment.

[0135] Figure 22 is a block diagram illustrating the schematic functional configuration of an authentication device (terminal device) according to one embodiment. As shown in the figure, the authentication device 2 according to one embodiment comprises an authentication unit 11, a processing control unit 12, a processing unit 13, and a fan 31. The authentication unit 11 also comprises a stimulus generation unit 21, an analysis unit 22, a determination unit 23, a device-specific identification information acquisition unit 28, and an acquisition unit 33. As in the previous embodiment, the device-specific environment 39 includes the acoustic environment specific to each individual authentication device 2.

[0136] A key feature of this embodiment is that the authentication device 2 includes a device-specific identification information acquisition unit 28.

[0137] The device-specific identification information acquisition unit 28 acquires device-specific identification information and provides it to the stimulus generation unit 21 and the analysis unit 22. The device-specific identification information is, for example, a device serial number, which has a unique value for each individual authentication device 1. In other words, the device-specific identification information is information unique to the authentication device 1. The device-specific identification information acquisition unit 28 reads the device serial number, etc., recorded in the authentication device 1. This device serial number, etc., may be, for example, a manufacturing serial number assigned at the time of manufacture. The purpose and method of using the device-specific identification information will be described later.

[0138] In this embodiment, the stimulus generation unit 21 may change the length of the period during which it drives the fan 31 with pulse width modulated power according to a predetermined pulse width, in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit 28. Specific examples of variations in the length of the period will be explained later with reference to another figure.

[0139] In this case, the analysis unit 22 analyzes the response from the authentication device 1 based on the length of the operating period, according to the device's unique identification information.

[0140] Furthermore, in this embodiment, the stimulus generation unit 21 may change the series of numerical values ​​representing the pulse width for each period in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit 28. In other words, the stimulus generation unit 21 may change the series of percentage values ​​for PWM.

[0141] In this case, the analysis unit 22 analyzes the response from the authentication device 1 according to the sequence of numerical values ​​used by the stimulus generation unit 21.

[0142] In other words, in this embodiment, the order of the percentage values ​​of PWM at each timing in the authentication key generation data is not limited to one type, but can be changed based on the device-specific identification information (serial number). This increases the cryptographic strength of the authentication key. In this case, the device-specific identification information acquisition unit 28 can be accessed from the API (application program interface) of the application program, etc. In other words, the device-specific identification information (serial number) can be acquired by software. As an example, the device-specific identification information (serial number) can be converted to binary and separated into even parity and odd parity cases.

[0143] In this embodiment, the length of the period for each timing and the authentication key generation data (a series of PWM percentage values) are made variable according to the device-specific identification information (serial number).

[0144] Figure 23 is a schematic diagram showing an example of changing the stimuli generated by the stimulus generation unit 21 according to the device-specific identification information. As shown in the figure, for example, the length of each timing from timing "1" to timing "5" may be changed according to the device-specific identification information. In the example shown, the length of the period is changed depending on whether the numerical value of the device-specific identification information is even parity or odd parity. Specifically, in the case of even parity, the length of one period is 2 seconds, and in the case of odd parity, the length of one period is 3 seconds.

[0145] Figure 24 is a schematic diagram showing an example where the stimulus generated by the stimulus generation unit 21 is changed according to the device-specific identification information. In the illustrated example, the stimulus generation unit 21 changes the authentication key generation data depending on whether the device-specific identification information is even parity or odd parity. Specifically, in the case of even parity, the percentage values ​​of the PWM from timing "1" to timing "5" are sequentially changed to 100%, 80%, 60%, 40%, and 20%. In the case of odd parity, the percentage values ​​of the PWM from timing "1" to timing "5" are sequentially changed to 100%, 20%, 40%, 80%, and 80%.

[0146] [Regarding variations] In the above embodiment, the length of each period and the authentication period generation data were changed according to the device-specific identification information (serial number, etc.). In other words, the stimulation generation unit 21 changed the length of the period during which it drove the fan with pulse width modulated power by a predetermined pulse width, according to the device-specific identification information acquired by the device-specific identification information acquisition unit 28. The stimulation generation unit 21 also changed the series of numerical values ​​representing the pulse width for each period, according to the device-specific identification information acquired by the device-specific identification information acquisition unit 28. As a variation, only one of the above-mentioned period length and the above-mentioned series of numerical values ​​representing the pulse width for each period may be changed according to the device-specific identification information (serial number, etc.).

[0147] Furthermore, the device-specific identification information does not have to be numerical; it just needs to be information unique to the device. Any device-specific identification information, not limited to numerical values, should be able to be mapped to multiple types of period lengths. Also, any device-specific identification information, not limited to numerical values, should be able to be mapped to multiple types of authentication period generation data (a column of percentage values ​​of PWM for each period).

[0148] In the above embodiment, device-specific identification information was distinguished using even parity and odd parity and mapped to two different period lengths. As a variation, device-specific identification information may be classified using other methods (methods other than parity) and mapped to two different period lengths.

[0149] In the above embodiment, device-specific identification information was distinguished by even parity and odd parity and mapped to authentication period generation data (a column of percentage values ​​of PWM for each period). As a modification, device-specific identification information may be classified by other methods (methods other than parity) and mapped to two types of authentication period generation data (a column of percentage values ​​of PWM for each period).

[0150] The number of classifications for device-specific identification information may be three or more types, or D types (where D is an integer greater than or equal to 3). In that case, for example, the D types may be 0, 1, ..., (D-1) based on the remainder when the device-specific identification information (integer value) is divided by the integer D.

[0151] According to this embodiment, a different stimulus can be generated for each authentication device 1, and authentication can be performed based on that stimulus.

[0152] <Third Embodiment> Hereinafter, one embodiment of the present disclosure will be described with reference to the figures. Note that matters already described in previous embodiments may be omitted below. Here, the focus will be on matters specific to this embodiment.

[0153] Figure 25 is a block diagram illustrating the schematic functional configuration of an authentication device (terminal device) according to one embodiment. As shown in the figure, the authentication device 3 according to one embodiment comprises an authentication unit 11, a processing control unit 12, a processing unit 13, and a fan 31. The authentication unit 11 also comprises a stimulus generation unit 21A, an analysis unit 22A, a determination unit 23, a device-specific identification information acquisition unit 28, and an acquisition unit 33.

[0154] The differences between the authentication device 2 with the configuration described above and the authentication device 3 in this embodiment are as follows: In other words, the authentication device 3 in this embodiment is equipped with a stimulus generation unit 21A instead of a stimulus generation unit 21. Also, the authentication device 3 in this embodiment is equipped with an analysis unit 22A instead of an analysis unit 22.

[0155] In this embodiment, the stimulation generation unit 21A provides a period during which the fan 31 is stopped from running. In other words, the stimulation generation unit 21 can temporarily supply power to drive the fan 31, for example, within a range that does not cause problems (adverse effects) on the overall cooling performance of the authentication device 1.

[0156] Furthermore, in this embodiment, the analysis unit 22A performs a correction when analyzing the sound that is the response of the authentication device 1 by subtracting the sound acquired during the period when the fan was stopped from the sound acquired during other periods. In other words, in both the process of generating the authentication master key and the process of generating the terminal authentication key, the analysis unit 22A performs a correction by subtracting the sound component (ambient sound) from when the fan 31 was stopped when the fan 31 was running and recording the sound.

[0157] Through this correction process, the authentication device 3 can eliminate the influence of ambient noise during both the generation of the authentication master key and the generation of the terminal authentication key.

[0158] In other words, in this embodiment, in order to eliminate the influence of the environment (noise around the device), the fan is stopped to the extent that it does not affect the cooling of the device, and ambient noise is collected. When generating the authentication master key and the terminal authentication key, the ambient noise (sound pressure level according to the frequency characteristics) is corrected to cancel it out.

[0159] According to this embodiment, errors that may be caused by ambient noise can be reduced.

[0160] <Fourth Embodiment> Hereinafter, one embodiment of the present disclosure will be described with reference to the figures. Note that matters already described in previous embodiments may be omitted below. Here, the focus will be on matters specific to this embodiment.

[0161] Figure 26 is a block diagram illustrating the schematic functional configuration of an authentication device (terminal device) according to an embodiment. As shown in the figure, the authentication device 4 according to one embodiment includes an authentication unit 11. The authentication unit 11 also includes a stimulus generation unit 21, an analysis unit 22, a determination unit 23, and an acquisition unit 33.

[0162] The authentication unit 11 performs the authentication process. In other words, the authentication unit 11 determines whether or not the user has the authority to perform the predetermined process.

[0163] The stimulus generation unit 21 generates stimuli to be applied to the component device 30. The stimulus generation unit 21 drives the component device 30 using the generated stimuli. The stimuli generated by the stimulus generation unit 21 may be, for example, a power pattern (a pattern that changes over time) that drives the component device 30. The component device 30 and the device-specific environment 39 output responses corresponding to the above stimuli.

[0164] In other words, the authentication method of this embodiment is as follows: The stimulus generation unit 21 generates stimuli for the constituent device 30. The acquisition unit 33 acquires the response within the device based on the stimuli generated by the stimulus generation unit 21. The analysis unit 22 analyzes the response acquired by the acquisition unit 33 and extracts the characteristics of that response. The determination unit 23 determines whether authentication is OK or NG based on the master key, which is a characteristic previously extracted and stored by the analysis unit 22, and the authentication key, which is a characteristic extracted by the analysis unit 22 during authentication.

[0165] Note that component 30 may be something other than a fan. For example, component 30 may be a hard disk drive. In other words, the stimulus generation unit 21 outputs a signal to control the rotation speed of the hard disk drive. Also, the stimulus generated by the stimulus generation unit 21 may be something other than a power pattern. For example, the stimulus may be a light stimulus, a heat stimulus, or an electromagnetic wave stimulus.

[0166] According to this embodiment, it becomes possible to perform authentication using features unique to the authentication device 4.

[0167] Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure are possible, which can be understood by those skilled in the art within the scope of the present disclosure. Each embodiment (including its variations) can be combined with other embodiments (including its variations) as appropriate.

[0168] Some or all of the above embodiments may also be described as follows, but are not limited to the following:

[0169] (Note 1) A stimulus generation unit that generates stimuli for the constituent devices, An acquisition unit that acquires the response within the device based on the stimulus generated by the stimulus generation unit, An analysis unit analyzes the response acquired by the acquisition unit and extracts the characteristics of the response, A determination unit determines whether authentication is OK or NG based on the master key, which is the characteristic that the analysis unit has previously extracted and stored, and the authentication key, which is the characteristic that the analysis unit extracted during authentication. An authentication device equipped with the following features.

[0170] (Note 2) The aforementioned component is a fan, The stimulus generated by the stimulus generation unit is a power pattern that drives the fan. The response corresponding to the stimulus is a sound emitted from the fan and acquired through the device-specific environment, which is an environment unique to the authentication device. The authentication device described in Appendix 1.

[0171] (Note 3) The stimulus generation unit generates the power pattern based on the given authentication key generation data. The power pattern that drives the fan is pulse-width modulated power with a predetermined pulse width. The authentication key generation data is a series of numerical values ​​representing the pulse width for each period. The authentication device described in Appendix 2.

[0172] (Note 4) The device includes a device-specific identification information acquisition unit that acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the length of the period during which it drives the fan with pulse width modulated power according to a predetermined pulse width, in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The analysis unit analyzes the response based on the length of the operating period according to the device's unique identification information. The authentication device described in Appendix 3.

[0173] (Note 5) The device includes a device-specific identification information acquisition unit that acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the sequence of numerical values ​​representing the pulse width for each period in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The authentication device described in Appendix 3 or Appendix 4.

[0174] (Note 6) The stimulus generating unit provides a period during which the fan is turned off. When the analysis unit analyzes the sound, which is the response, it performs a correction by subtracting the sound acquired during the period when the fan was stopped from the sound acquired during other periods. The authentication device described in any one of the appendices 2 through 5.

[0175] (Note 7) The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level for each frequency of the sound. The authentication device described in any one of the appendices 2 through 6.

[0176] (Note 8) The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level of one or more samples of the frequency of the sound. The authentication device described in Appendix 7.

[0177] (Note 9) The stimulus generation unit generates stimuli for the constituent devices. The acquisition unit acquires the response within the device based on the stimulus generated by the stimulus generation unit. The analysis unit analyzes the response acquired by the acquisition unit and extracts the characteristics of the response. The determination unit determines whether authentication is OK or NG based on the master key, which is the characteristic that the analysis unit has previously extracted and stored, and the authentication key, which is the characteristic that the analysis unit extracted during authentication. Authentication method.

[0178] (Note 10) A stimulus generation unit that generates stimuli for the constituent devices, An acquisition unit that acquires the response within the device based on the stimulus generated by the stimulus generation unit, An analysis unit analyzes the response acquired by the acquisition unit and extracts the characteristics of the response, A determination unit determines whether authentication is OK or NG based on the master key, which is the characteristic that the analysis unit has previously extracted and stored, and the authentication key, which is the characteristic that the analysis unit extracted during authentication. A program that allows a computer to function as an authentication device equipped with [specific features / functions].

[0179] (Note 11) The stimulus generation unit generates the power patterns for each of the multiple periods based on the authentication key generation data. The acquisition unit acquires the sound which is the response at each of the periods, When the analysis unit analyzes the sound, which is the response, it extracts the result of subtracting the sound pressure level for each frequency in a second period different from the first period from the sound pressure level for each frequency in the first period, as the feature. The authentication device described in Appendix 3.

[0180] (Note 12) A processing unit for running an application program, A processing control unit controls the operation of a specific application program on the processing unit if the determination unit determines that authentication is OK, and controls the operation of the specific application program on the processing unit if the determination unit determines that authentication is NG. The authentication device described in Appendix 1 to Appendix 8, or Appendix 11, further comprising the above.

[0181] (Note 13) The aforementioned component is a fan, The stimulus generated by the stimulus generation unit is a power pattern that drives the fan. The response corresponding to the stimulus is a sound emitted from the fan and acquired through the device-specific environment, which is an environment unique to the authentication device. The authentication method described in Appendix 9.

[0182] (Note 14) The stimulus generation unit generates the power pattern based on the given authentication key generation data. The power pattern that drives the fan is pulse-width modulated power with a predetermined pulse width. The authentication key generation data is a series of numerical values ​​representing the pulse width for each period. The authentication method described in Appendix 13.

[0183] (Note 15) The device-specific identification information acquisition unit acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the length of the period during which it drives the fan with pulse width modulated power according to a predetermined pulse width, in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The analysis unit analyzes the response based on the length of the operating period according to the device's unique identification information. The authentication method described in Appendix 14.

[0184] (Note 16) The device-specific identification information acquisition unit acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the sequence of numerical values ​​representing the pulse width for each period in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The authentication method described in Appendix 14 or Appendix 15.

[0185] (Note 17) The stimulus generating unit provides a period during which the fan is turned off. When the analysis unit analyzes the sound, which is the response, it performs a correction by subtracting the sound acquired during the period when the fan was stopped from the sound acquired during other periods. The authentication method described in any one of the appendices 13 through 16.

[0186] (Note 18) The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level for each frequency of the sound. The authentication method described in any one of the appendices 13 through 17.

[0187] (Note 19) The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level of one or more samples of the frequency of the sound. Authentication method as described in Appendix 18.

[0188] (Note 20) The stimulus generation unit generates the power patterns for each of the multiple periods based on the authentication key generation data. The acquisition unit acquires the sound which is the response at each of the periods, When the analysis unit analyzes the sound, which is the response, it extracts the result of subtracting the sound pressure level for each frequency in a second period different from the first period from the sound pressure level for each frequency in the first period, as the feature. The authentication method described in Appendix 14.

[0189] (Note 21) A processing unit for running an application program, A processing control unit controls the operation of a specific application program on the processing unit if the determination unit determines that authentication is OK, and controls the operation of the specific application program on the processing unit if the determination unit determines that authentication is NG. The authentication methods described in Appendix 9, or in Appendix 13 to Appendix 20, further comprising the above.

[0190] (Note 22) The aforementioned component is a fan, The stimulus generated by the stimulus generation unit is a power pattern that drives the fan. The response corresponding to the stimulus is a sound emitted from the fan and acquired through the device-specific environment, which is an environment unique to the authentication device. The program described in Appendix 10.

[0191] (Note 23) The stimulus generation unit generates the power pattern based on the given authentication key generation data. The power pattern that drives the fan is pulse-width modulated power with a predetermined pulse width. The authentication key generation data is a series of numerical values ​​representing the pulse width for each period. The program described in Appendix 22.

[0192] (Note 24) The device includes a device-specific identification information acquisition unit that acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the length of the period during which it drives the fan with pulse width modulated power according to a predetermined pulse width, in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The analysis unit analyzes the response based on the length of the operating period according to the device's unique identification information. The program described in Appendix 23.

[0193] (Note 25) The device includes a device-specific identification information acquisition unit that acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the sequence of numerical values ​​representing the pulse width for each period in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The program described in Appendix 23 or Appendix 24.

[0194] (Note 26) The stimulus generating unit provides a period during which the fan is turned off. When the analysis unit analyzes the sound, which is the response, it performs a correction by subtracting the sound acquired during the period when the fan was stopped from the sound acquired during other periods. The program described in any one of the appendices 22 through 25.

[0195] (Note 27) The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level for each frequency of the sound. The program described in any one of the appendices 22 through 26.

[0196] (Note 28) The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level of one or more samples of the frequency of the sound. The program described in Appendix 27.

[0197] (Note 29) The stimulus generation unit generates the power patterns for each of the multiple periods based on the authentication key generation data. The acquisition unit acquires the sound which is the response at each of the periods, When the analysis unit analyzes the sound, which is the response, it extracts the result of subtracting the sound pressure level for each frequency in a second period different from the first period from the sound pressure level for each frequency in the first period, as the feature. The program described in Appendix 23.

[0198] (Note 30) A processing unit for running an application program, A processing control unit controls the operation of a specific application program on the processing unit if the determination unit determines that authentication is OK, and controls the operation of the specific application program on the processing unit if the determination unit determines that authentication is NG. The programs described in Appendix 10, or in Appendix 22 to Appendix 29, further comprising the above. [Explanation of Symbols]

[0199] 1,2,3,4 Authentication device (terminal device) 11. Authentication Department 12 Processing Control Unit 13 Processing Unit 21 Stimulus generation section 22 Analysis Department 23 Judgment section 28. Device-Specific Identification Information Acquisition Unit 31 Fans 32 Microphones 33 Acquisition Department 39 Device-specific environment 51, 52 Mounted components 53 Mechanical parts 901 Central Processing Unit 902 RAM 903 Input / Output Ports 904,905 Input / Output Devices 906 Bus

Claims

1. A stimulus generation unit that generates stimuli for the constituent devices, An acquisition unit that acquires the response within the device based on the stimulus generated by the stimulus generation unit, An analysis unit analyzes the response acquired by the acquisition unit and extracts the characteristics of the response, A determination unit determines whether authentication is OK or NG based on the master key, which is the characteristic that the analysis unit has previously extracted and stored, and the authentication key, which is the characteristic that the analysis unit extracted during authentication. Equipped with, The aforementioned component is a fan, The stimulus generated by the stimulus generation unit is a power pattern that drives the fan. The response corresponding to the stimulus is a sound emitted from the fan and acquired via the device-specific environment, which is an environment unique to the authentication device. The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level for each frequency of the sound. Authentication device.

2. The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level of one or more samples of the frequency of the sound. The authentication device according to claim 1.

3. The stimulus generation unit generates the power pattern based on the given authentication key generation data. The power pattern that drives the fan is pulse-width modulated power with a predetermined pulse width. The authentication key generation data is a series of numerical values ​​representing the pulse width for each period. The authentication device according to claim 1.

4. The stimulus generation unit generates the power patterns for each of the multiple periods based on the authentication key generation data. The acquisition unit acquires the sound which is the response at each of the periods, When the analysis unit analyzes the sound, which is the response, it extracts the result of subtracting the sound pressure level for each frequency in a second period different from the first period from the sound pressure level for each frequency in the first period, as the feature. The authentication device according to claim 3.

5. The device includes a device-specific identification information acquisition unit that acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the length of the period during which it drives the fan with pulse width modulated power according to a predetermined pulse width, in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The analysis unit analyzes the response based on the length of the operating period according to the device's unique identification information. The authentication device according to claim 3.

6. The device includes a device-specific identification information acquisition unit that acquires device-specific identification information, which is information unique to the authentication device. The stimulus generation unit changes the sequence of numerical values ​​representing the pulse width for each period in accordance with the device-specific identification information acquired by the device-specific identification information acquisition unit. The authentication device according to claim 3.

7. The stimulus generating unit provides a period during which the fan is turned off. When the analysis unit analyzes the sound, which is the response, it performs a correction by subtracting the sound acquired during the period when the fan was stopped from the sound acquired during other periods. The authentication device according to claim 1.

8. The stimulus generation unit generates stimuli for the constituent devices. The acquisition unit acquires the response within the device based on the stimulus generated by the stimulus generation unit. The analysis unit analyzes the response acquired by the acquisition unit and extracts the characteristics of the response. The determination unit determines whether authentication is OK or NG based on the master key, which is the characteristic that the analysis unit has previously extracted and stored, and the authentication key, which is the characteristic that the analysis unit extracted during authentication. Authentication method, The aforementioned component is a fan, The stimulus generated by the stimulus generation unit is a power pattern that drives the fan. The response corresponding to the stimulus is a sound emitted from the fan and acquired via the device-specific environment, which is an environment unique to the authentication device. The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level for each frequency of the sound. Authentication method.

9. A stimulus generation unit that generates stimuli for the constituent devices, An acquisition unit that acquires the response within the device based on the stimulus generated by the stimulus generation unit, An analysis unit analyzes the response acquired by the acquisition unit and extracts the characteristics of the response, A determination unit determines whether authentication is OK or NG based on the master key, which is the characteristic that the analysis unit has previously extracted and stored, and the authentication key, which is the characteristic that the analysis unit extracted during authentication. An authentication device equipped with, The aforementioned component is a fan, The stimulus generated by the stimulus generation unit is a power pattern that drives the fan. The response corresponding to the stimulus is a sound emitted from the fan and acquired via the device-specific environment, which is an environment unique to the authentication device. The analysis unit, when analyzing the sound which is the response, extracts the characteristics of the response by performing an analysis based on the sound pressure level for each frequency of the sound. A program that allows a computer to function as an authentication device.

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