JP2021071413A - Satellite positioning system, ground receiver, and position calculation method - Google Patents

Abstract

To provide a satellite positioning system, a ground receiver, and a position calculation method that can improve security when calculating a position using a positioning signal.SOLUTION: In a satellite positioning system 1 of the present invention, a management device 20 transmits encryption keys corresponding to respective signal certificates to a ground receiver 40. The management device 20 also transmits a positioning signal with signature to which identification information on one signal certificate and an electronic signature encrypted with the encryption key corresponding to the signal certificate are attached to a positioning satellite 30. The ground receiver 40 uses a hash value obtained by decrypting the electronic signature with the encryption key corresponding to the positioning signal with signature received from the positioning satellite 30 among the encryption keys provided by the management device 20 and a hash value based on the identification information on the signal certificate attached to the positioning signal with signature and the positioning signal with signature to authenticate the positioning signal with signature and uses the authenticated positioning signal with signature to calculate the position.SELECTED DRAWING: Figure 1

Description

The present invention relates to a satellite positioning system for calculating the position of a ground receiver, a ground receiver, and a position calculation method.

Conventionally, various techniques have been proposed to prevent fraud and forgery when calculating a position using a positioning signal received from a positioning satellite. For example, in the position information authentication system disclosed in Patent Document 1, the receiver receives an encrypted RAND message included in a navigation message received from the QZS satellite and an encrypted RAND message recorded in the authentication center. Use to authenticate navigation messages.

Japanese Patent No. 5667967

However, the location information authentication system disclosed in Patent Document 1 does not take measures when the confidentiality of the cipher cannot be maintained, and has a problem that the security against fraud and forgery is low.

An object of the present invention is to provide a satellite positioning system, a ground receiver, and a position calculation method capable of improving security when calculating a position using a positioning signal in view of the above-mentioned problems.

The satellite positioning system according to an embodiment of the present invention processes a positioning signal transmitted by a plurality of positioning satellites and provides the management device to the plurality of positioning satellites, and a plurality of positioning signals received from the plurality of positioning satellites. Includes a ground receiver that uses it to calculate the position of its own aircraft. The management device is a signal certificate generator that generates a plurality of signal certificates for the ground receiver to authenticate the positioning signal, and an encryption key generation unit that generates a plurality of encryption keys corresponding to each of the plurality of signal certificates. A signal certificate transmitter that transmits a unit, an encryption key corresponding to each of a plurality of signal certificates to a terrestrial receiver, identification information of one of the plurality of signal certificates, and the signal. A signed positioning signal generator that generates a signed positioning signal by adding an electronic signature encrypted using an encryption key corresponding to the signal certificate indicated by the identification information of the certificate to the positioning signal, and a signature. It is provided with a signed positioning signal transmission unit that transmits a positioning signal to a plurality of positioning satellites. The terrestrial receiver includes a signal certificate receiving unit that receives an encryption key corresponding to each of a plurality of signal certificates transmitted by the management device, a positioning signal receiving unit that receives a signed positioning signal from a plurality of positioning satellites, and a positioning signal receiving unit. An electron that decrypts the electronic signature attached to the signed positioning signal and calculates the hash value by using the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate attached to the signed positioning signal. A signature verification unit, a signed positioning signal, a hash value generator that generates a hash value from the identification information of the signal certificate attached to the signed positioning signal, and a signed positioning signal using these hash values. It is provided with a positioning signal authentication unit that authenticates the above, and a position calculation unit that calculates the position of the ground receiver using the authenticated and signed positioning signal.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a satellite positioning system, a ground receiver, and a position calculation method capable of improving security when calculating a position using a positioning signal.

It is the schematic which shows one Embodiment of the satellite positioning system which concerns on one Embodiment of this invention. It is a block diagram which shows the function which the positioning signal transmitting apparatus which concerns on one Embodiment of this invention has. It is a block diagram which shows a part of the function which the management apparatus which concerns on one Embodiment of this invention has. It is a block diagram which shows the function which the positioning satellite which concerns on one Embodiment of this invention has. It is a sequence diagram which shows an example of the process executed by the satellite positioning system which concerns on one Embodiment of this invention. It is a block diagram which shows a part of the function which the terrestrial receiver which concerns on one Embodiment of this invention has. It is a block diagram which shows a part of the function which the management apparatus which concerns on one Embodiment of this invention has. It is a sequence diagram which shows another example of the process executed by the satellite positioning system which concerns on one Embodiment of this invention. It is a block diagram which shows a part of the function which the terrestrial receiver which concerns on one Embodiment of this invention has. It is a block diagram which shows a part of the function which the management apparatus which concerns on one Embodiment of this invention has. It is a sequence diagram which shows another example of the process executed by the satellite positioning system which concerns on one Embodiment of this invention. It is a block diagram which shows a part of the function which the terrestrial receiver which concerns on one Embodiment of this invention has. It is a sequence diagram which shows another example of the process executed by the satellite positioning system which concerns on one Embodiment of this invention. It is a block diagram which shows the main function which the management apparatus and the ground receiver which concerns on one Embodiment of this invention have. It is a figure which shows an example of the list of the signal certificate provided to the ground receiver by the management apparatus which concerns on one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic view showing an embodiment of the satellite positioning system 1 of the present invention. The satellite positioning system 1 includes a positioning signal transmitting device 10, a management device 20, a plurality of positioning satellites 30, and a ground receiver 40. The positioning signal transmitting device 10 and the management device 20 can communicate data with each other via the network 50. Further, the management device 20 and the terrestrial receiver 40 can communicate data with each other via a communication device (not shown) and a network 60.

The positioning signal transmitting device 10 is a device that generates and transmits a positioning signal used in the satellite positioning system 1. When the positioning signal transmitting device 10 generates the positioning signal, the positioning signal transmitting device 10 provides the positioning signal to the management device 20 via the network 50. When the management device 20 receives the signed positioning signal to which the electronic signature is added, the positioning signal transmitting device 10 transmits the signed positioning signal to the plurality of positioning satellites 30.

The management device 20 is a device that processes the positioning signal generated by the positioning signal transmitting device 10 and provides it to the plurality of positioning satellites 30. The management device 20 is managed by a signal certificate issuing organization that guarantees that the positioning signal is a genuine positioning signal. The management device 20 includes an arithmetic unit, a storage device, and an input / output interface. The details of the function of the management device 20 will be described later. In the embodiment in which the ground receiver 40 is mounted on an automobile, the individual identification number of the automobile, the identification information of the ground receiver 40, and the information of the user of the automobile can be stored in the storage device of the management device 20. it can.

The positioning satellite 30 is an artificial satellite used in the satellite positioning system 1. As the positioning satellite 30, for example, a quasi-zenith satellite (QZS: Quasi Zenith Satellite) can be used. When the positioning satellite 30 receives the signed positioning signal from the positioning signal transmitting device 10, the positioning satellite 30 transmits the signed positioning signal to the ground receiver 40.

The ground receiver 40 is a device that calculates the position of its own device using a plurality of signed positioning signals received from a plurality of positioning satellites 30. The terrestrial receiver 40 includes an arithmetic unit, a storage device, an input / output interface, and an antenna. The ground receiver 40 can execute the position calculation method of the present invention by executing the position calculation program of the present invention by the arithmetic unit. The details of the function of the terrestrial receiver 40 will be described later.

FIG. 2 is a block diagram showing a function of the positioning signal transmitting device 10 according to the embodiment of the present invention. The positioning signal transmitting device 10 includes a positioning signal generation unit 100, a positioning signal transmitting unit 101, a signed positioning signal receiving unit 102, and a signed positioning signal transmitting unit 103. In the block diagram below, the flow of information between each functional unit is shown by using arrows, but the flow of information between each functional unit is not necessarily limited to one direction.

The positioning signal generation unit 100 is a functional unit that generates a positioning signal used in the satellite positioning system 1. When the positioning signal generation unit 100 generates a positioning signal, the positioning signal generation unit 100 provides the positioning signal transmission unit 101 with the positioning signal. The positioning signal transmission unit 101 is a functional unit that transmits the positioning signal generated by the positioning signal generation unit 100 to the management device 20. When the positioning signal transmission unit 101 receives the positioning signal from the positioning signal generation unit 100, the positioning signal transmission unit 101 transmits the positioning signal to the management device 20 via the network 50.

The signed positioning signal receiving unit 102 is a functional unit that receives the signed positioning signal transmitted by the management device 20. The signed positioning signal is a positioning signal to which an electronic signature and a signal certificate ID are added by the management device 20. The electronic signature is a signature that the signal certificate issuing organization certifies that the positioning signal is a genuine positioning signal. The signal certificate ID is identification information of a signal certificate that the signal certificate issuing organization certifies that the positioning signal is a genuine positioning signal. When the signed positioning signal receiving unit 102 receives the signed positioning signal from the management device 20, the signed positioning signal receiving unit 102 provides the signed positioning signal transmitting unit 103 with the signed positioning signal receiving unit 102. The signed positioning signal transmitting unit 103 is a functional unit that transmits the signed positioning signal provided by the signed positioning signal receiving unit 102 to a plurality of positioning satellites 30.

FIG. 3 is a block diagram showing a part of the functions of the management device 20 according to the embodiment of the present invention. The management device 20 includes a positioning signal receiving unit 200, an encryption key generation unit 201, a signal certificate generation unit 202, a hash value generation unit 203, an electronic signature generation unit 204, a signed positioning signal generation unit 205, and the like. It has a signed positioning signal transmission unit 206 and a signal certificate database (DB) 230.

The positioning signal receiving unit 200 is a functional unit that receives the positioning signal transmitted by the positioning signal transmitting device 10. When the positioning signal receiving unit 200 receives the positioning signal from the positioning signal transmitting device 10, the positioning signal receiving unit 200 provides the positioning signal to the hash value generating unit 203 and the signed positioning signal generating unit 205.

The encryption key generation unit 201 is a functional unit that generates a public key and a private key, which are encryption keys used for authenticating a positioning signal, by using an arbitrary encryption algorithm. The encryption key generation unit 201 generates a plurality of different public keys and private keys, and generates a plurality of public key and private key pairs. For example, the encryption key generation unit 201 can generate four public keys and private keys, and can generate four pairs of public keys and private keys. When the encryption key generation unit 201 generates a plurality of pairs of encryption keys, the encryption key generation unit 201 provides these encryption keys to the signal certificate generation unit 202 and the electronic signature generation unit 204.

The signal certificate generation unit 202 is a functional unit that generates a signal certificate. The signal certificate generation unit 202 generates a signal certificate for each pair of the public key and the private key generated by the encryption key generation unit 201. For example, when the encryption key generation unit 201 generates four pairs of public key and private key, the signal certificate generation unit 202 generates four signal certificates corresponding to each of these public key and private key pairs. Generate. When the signal certificate generation unit 202 generates the signal certificate, the signal certificate is associated with the signal certificate ID and stored in the signal certificate DB 230. The signal certificate stored in the signal certificate DB 230 includes a public key corresponding to the signal certificate. Further, the signal certificate generation unit 202 provides the signal certificate ID to the hash value generation unit 203 and the signed positioning signal generation unit 205.

The hash value generation unit 203 uses an arbitrary hash function to generate a hash value from the positioning signal provided by the positioning signal receiving unit 200 and one of a plurality of signal certificate IDs provided by the signal certificate generating unit 202. It is a functional part that generates. The signal certificate ID used when generating the hash value can be specified by the administrator of the management device 20. Further, the hash value generation unit 203 may randomly select a signal certificate ID from a plurality of signal certificate IDs provided by the signal certificate generation unit 202. When the hash value generation unit 203 generates the hash value, the hash value generation unit 203 provides the hash value to the electronic signature generation unit 204.

The electronic signature generation unit 204 is a functional unit that generates an electronic signature from the hash value provided by the hash value generation unit 203. For example, the electronic signature generation unit 204 uses one of the plurality of private keys provided by the encryption key generation unit 201 to encrypt the hash value provided by the hash value generation unit 203 to generate an electronic signature. Can be done. The private key used when encrypting the hash value is a private key associated with the signal certificate indicated by the signal certificate ID used when generating the hash value. When the electronic signature generation unit 204 generates an electronic signature, the electronic signature generation unit 204 provides the electronic signature to the signed positioning signal generation unit 205.

The signed positioning signal generation unit 205 uses the positioning signal provided by the positioning signal receiving unit 200, the electronic signature provided by the electronic signature generation unit 204, and the signal certificate ID provided by the signal certificate generation unit 202. It is a functional unit that generates a signed positioning signal. Specifically, the signed positioning signal generation unit 205 uses the electronic signature and the signal certificate ID of the signal certificate corresponding to the private key used when generating the electronic signature as the navigation message of the positioning signal. A signed positioning signal is generated by writing in the free area. When the signed positioning signal generation unit 205 generates the signed positioning signal, the signed positioning signal generation unit 205 provides the signed positioning signal transmission unit 206.

The signed positioning signal transmitting unit 206 is a functional unit that transmits the signed positioning signal provided by the signed positioning signal generation unit 205 to the positioning signal transmitting device 10. When the signed positioning signal transmitting unit 206 receives the signed positioning signal from the signed positioning signal generating unit 205, the signed positioning signal transmitting unit 206 transmits the signed positioning signal to the positioning signal transmitting device 10 via the network 50.

FIG. 4 is a block diagram showing a function of the positioning satellite 30 according to the embodiment of the present invention. The positioning satellite 30 has a positioning signal receiving unit 300 and a positioning signal transmitting unit 301. The positioning signal receiving unit 300 is a functional unit that provides the positioning signal transmitting unit 301 with the signed positioning signal transmitted by the positioning signal transmitting device 10. The positioning signal transmitting unit 301 is a functional unit that transmits the signed positioning signal provided by the positioning signal receiving unit 300 to the ground receiver 40. The positioning signal receiving unit 300 receives a conventional positioning signal without an electronic signature transmitted by another positioning signal transmitting device, and the positioning signal transmitting unit 301 transmits the positioning signal to the ground receiver 40. can do.

FIG. 5 is a sequence diagram showing a process executed in the satellite positioning system 1 according to the embodiment of the present invention. Hereinafter, with reference to FIG. 5, a process from the positioning signal transmitting device 10 generating the positioning signal to transmitting the signed positioning signal generated by the management device 20 to the positioning satellite 30 will be described.

In step S10, the positioning signal transmitting device 10 generates a positioning signal, and in step S11, the positioning signal is transmitted to the management device 20. When the management device 20 receives the positioning signal from the positioning signal transmitting device 10, the management device 20 generates a hash value from the positioning signal and the signal certificate ID in step S12. In step S13, the management device 20 encrypts the hash value and generates an electronic signature by using the private key corresponding to the signal certificate indicated by the signal certificate ID. In step S14, the management device 20 generates a signed positioning signal by writing the signal certificate ID and the electronic signature in the free area of the navigation message of the positioning signal. In step S15, the management device 20 transmits the signed positioning signal to the positioning signal transmitting device 10. Upon receiving the signed positioning signal, the positioning signal transmitting device 10 transmits the signed positioning signal to the positioning satellite 30 in step S16.

FIG. 6 is a block diagram showing a part of the functions of the ground receiver 40 according to the embodiment of the present invention. The terrestrial receiver 40 has a signal certificate request generation unit 400, a hash value generation unit 401, an electronic signature generation unit 402, and a signal certificate request transmission unit 403.

The signal certificate request generation unit 400 is a functional unit that generates a signal certificate request requesting the management device 20 to provide a signal certificate. The signal certificate request generation unit 400 generates a signal certificate request based on the instructions of the administrator of the management device 20 and the user of the ground receiver 40 in a state where the ground receiver 40 can communicate with the management device 20. Can be done.

The hash value generation unit 401 is a functional unit that generates a hash value from the signal certificate request generated by the signal certificate request generation unit 400 by using an arbitrary hash function. When the signal certificate request generation unit 400 generates a signal certificate request, the hash value generation unit 401 generates a hash value from the signal certificate request.

The electronic signature generation unit 402 is a functional unit that generates an electronic signature from the hash value generated by the hash value generation unit 401. For example, the electronic signature generation unit 402 can encrypt the hash value generated by the hash value generation unit 401 using the private key of the certificate of the terrestrial receiver 40 to generate an electronic signature. The private key of the certificate of the terrestrial receiver 40 can be provided in advance by an external organization. When the hash value generation unit 401 generates a hash value, the electronic signature generation unit 402 generates an electronic signature from the hash value.

The signal certificate request transmission unit 403 discloses the signal certificate request generated by the signal certificate request generation unit 400, the electronic signature generated by the electronic signature generation unit 402, the certificate of the ground receiver 40, and the certificate. It is a functional unit that transmits the key to the management device 20. The certificate of the terrestrial receiver 40 and the public key of the certificate can be provided in advance by an external organization.

FIG. 7 is a block diagram showing a part of the functions of the management device 20 according to the embodiment of the present invention. The management device 20 includes a signal certificate request receiving unit 207, a ground receiver authentication unit 208, an electronic signature verification unit 209, a hash value generation unit 210, a signal certificate request authentication unit 211, and a receipt generation unit 212. The receipt DB 213, the signal certificate encryption unit 214, the common key encryption unit 215, the hash value generation unit 216, the electronic signature generation unit 217, and the signal certificate transmission unit 218 are further included.

The signal certificate request receiving unit 207 is a functional unit that receives the signal certificate request, the electronic signature, the certificate of the terrestrial receiver 40, and the public key of the certificate transmitted by the terrestrial receiver 40. The terrestrial receiver authentication unit 208 authenticates the certificate of the terrestrial receiver 40 received by the signal certificate request receiving unit 207 and the public key of the certificate by using the certificate of the external organization, thereby performing the terrestrial receiver. It is a functional unit that authenticates 40. The certificate of the external organization includes the certificate of the ground receiver 40 and the information of the public key of the certificate, and can be provided by the external organization in advance.

The electronic signature verification unit 209 is a functional unit that calculates a hash value from the electronic signature received by the signal certificate request receiving unit 207. For example, the electronic signature verification unit 209 decrypts the electronic signature received by the signal certificate request receiving unit 207 using the public key of the certificate of the ground receiver 40 authenticated by the ground receiver authentication unit 208, and hashes it. The value can be calculated. When the ground receiver 40 is authenticated by the ground receiver authentication unit 208, the electronic signature verification unit 209 calculates a hash value from the electronic signature.

The hash value generation unit 210 is a functional unit that uses a hash function to generate a hash value from the signal certificate request received by the signal certificate request receiving unit 207. This hash function is the same as the hash function used by the hash value generation unit 401 of the ground receiver 40.

The signal certificate request authentication unit 211 compares the hash value calculated by the electronic signature verification unit 209 with the hash value generated by the hash value generation unit 210, and authenticates the signal certificate request transmitted by the ground receiver 40. It is a functional part. When these hash values are the same, the signal certificate request authentication unit 211 determines that the signal certificate request transmitted by the terrestrial receiver 40 has not been tampered with in the transmission path.

The receipt generation unit 212 is a functional unit that generates a receipt certifying that the ground receiver 40 has received the signal certificate from the management device 20. When the receipt generation unit 212 generates a receipt, it stores it in the receipt DB 213.

The signal certificate encryption unit 214 is a functional unit that encrypts a plurality of signal certificates and receipts provided to the ground receiver 40. The signal certificate encryption unit 214 acquires a plurality of signal certificates from the signal certificate DB, and encrypts these signal certificates and the receipt generated by the receipt generation unit 212 using a common key. .. The signal certificate encryption unit 214 can acquire and encrypt four signal certificates, for example. Each of these signal certificates includes a corresponding public key generated by the encryption key generator 201.

The common key encryption unit 215 encrypts the common key used for encrypting the signal certificate and the receipt by using the public key of the certificate of the ground receiver 40 received by the signal certificate request receiving unit 207. It is a functional part to do.

The hash value generation unit 216 is a functional unit that calculates a hash value from a signal certificate and a receipt encrypted by the common key encryption unit 215 using an arbitrary hash function. The electronic signature generation unit 217 is a functional unit that generates an electronic signature from the hash value generated by the hash value generation unit 216. For example, the electronic signature generation unit 217 can generate an electronic signature by encrypting the hash value generated by the hash value generation unit 216 by using the private key of the certificate of the management device 20. The private key of the certificate of the management device 20 can be provided in advance by an external organization.

The signal certificate transmission unit 218 generates a plurality of signal certificates and receipts encrypted by the signal certificate encryption unit 214, a common key encrypted by the common key encryption unit 215, and an electronic signature generation unit 217. It is a functional unit that transmits the digital signature, the certificate of the management device 20, and the public key of the certificate to the ground receiver 40. The certificate of the management device 20 and the public key of the certificate can be provided in advance by an external organization.

FIG. 8 is a sequence diagram showing a process executed in the satellite positioning system 1 according to the embodiment of the present invention. In the embodiment in which the ground receiver 40 is mounted on an automobile, a worker at a dealer or the like executes a series of processes shown in FIGS. 8 and 11 by connecting the ground receiver 40 to the network 60. Hereinafter, with reference to FIG. 8, the process from the generation of the signal certificate request to the management device 20 by the ground receiver 40 to the reception of the signal certificate from the management device 20 will be described.

In step S20, the ground receiver 40 generates a signal certificate request. In step S21, the ground receiver 40 generates a hash value from the signal certificate request. In step S22, the terrestrial receiver 40 encrypts the hash function to generate an electronic signature. In step S23, the terrestrial receiver 40 transmits the electronic signature, the certificate of the terrestrial receiver 40, and the public key of the certificate to the management device 20 together with the signal certificate request.

When the management device 20 receives the electronic signature, the certificate of the ground receiver 40, and the public key of the certificate together with the signal certificate request from the ground receiver 40, the management device 20 authenticates the ground receiver 40 in step S24. When the terrestrial receiver 40 is authenticated, the management device 20 decodes the electronic signature received from the terrestrial receiver 40 in step S25 to obtain a hash value. In step S26, the management device 20 generates a hash value from the signal certificate request received from the ground receiver 40. In step S27, the management device 20 authenticates the signal certificate request using these hash values.

If the signal certificate request is authenticated, i.e., the signal certificate request has not been tampered with, the management device 20 generates a receipt in step S28. In step S29, the management device 20 encrypts the plurality of signal certificates and receipts using the common key. In step S30, the management device 20 encrypts the common key using the public key of the certificate of the ground receiver 40. In step S31, the management device 20 calculates the hash value from the encrypted signal certificate and the receipt. In step S32, the management device 20 encrypts the hash value using the private key of the certificate of the management device 20 to generate an electronic signature. In step S33, the management device 20 obtains a plurality of encrypted signal certificates and receipts, an encrypted common key, a digital signature, a certificate of the management device 20, and a public key of the certificate. It transmits to the ground receiver 40.

FIG. 9 is a block diagram showing a part of the functions of the ground receiver 40 according to the embodiment of the present invention. The terrestrial receiver 40 includes a signal certificate receiving unit 404, a management device authentication unit 405, an electronic signature verification unit 406, a hash value generation unit 407, a signal certificate authentication unit 408, a common key decryption unit 409, and the like. It further includes a signal certificate decoding unit 410, a signal certificate DB 411, a hash value generation unit 412, an electronic signature generation unit 413, and a receipt transmission unit 414.

The signal certificate receiving unit 404 includes a plurality of encrypted signal certificates and receipts transmitted by the management device 20, an encrypted common key, an electronic signature, a certificate of the management device 20, and the certificate. It is a functional part that receives the public key of.

The management device authentication unit 405 authenticates the management device 20 by authenticating the certificate of the management device 20 received by the signal certificate receiving unit 404 and the public key of the certificate using the certificate of an external organization. It is a functional part. The certificate of the external organization includes the certificate of the management device 20 and the information of the public key of the certificate, and can be provided by the external organization in advance.

The electronic signature verification unit 406 is a functional unit that calculates a hash value from the electronic signature received by the signal certificate receiving unit 404. For example, the electronic signature verification unit 406 decrypts the electronic signature received by the signal certificate receiving unit 404 using the public key of the certificate of the management device 20 authenticated by the management device authentication unit 405, and calculates the hash value. can do. When the management device 20 is authenticated by the management device authentication unit 405, the electronic signature verification unit 406 calculates a hash value from the electronic signature.

The hash value generation unit 407 is a functional unit that uses a hash function to generate a hash value from a plurality of encrypted signal certificates and receipts received by the signal certificate receiving unit 404 and an encrypted common key. Is. This hash function is the same as the hash function used by the hash value generation unit 216 of the management device 20.

The signal certificate authentication unit 408 compares the hash value calculated by the electronic signature verification unit 406 with the hash value generated by the hash value generation unit 407, and authenticates the signal certificate and the receipt transmitted by the management device 20. It is a functional part. When these hash values are the same, the signal certificate authentication unit 408 determines that the signal certificate and the receipt transmitted by the management device 20 have not been tampered with in the transmission path.

The common key decryption unit 409 is a functional unit that decrypts the encrypted common key received by the signal certificate receiving unit 404 using the private key of the certificate of the terrestrial receiver 40.

The signal certificate decryption unit 410 is a functional unit that decrypts a plurality of encrypted signal certificates and receipts received by the signal certificate receiving unit 404 using the common key decrypted by the common key decoding unit 409. .. If the signal certificate and the receipt have not been tampered with, the signal certificate decryption unit 410 decrypts the plurality of encrypted signal certificates and the receipt, and saves the decrypted signal certificate in the signal certificate DB411. .. The signal certificate stored in the signal certificate DB411 includes a public key corresponding to the signal certificate.

The hash value generation unit 412 is a functional unit that calculates a hash value from a receipt decrypted by the signal certificate decoding unit 410 using a hash function. The hash value generation unit 412 calculates the hash value from the receipt if the receipt has not been tampered with. The electronic signature generation unit 413 is a functional unit that generates an electronic signature from the hash value generated by the hash value generation unit 412. For example, the electronic signature generation unit 413 can generate an electronic signature by encrypting the hash value generated by the hash value generation unit 412 by using the private key of the certificate of the ground receiver 40.

The receipt transmission unit 414 manages the receipt decrypted by the signal certificate decryption unit 410, the electronic signature generated by the electronic signature generation unit 413, the certificate of the ground receiver 40, and the public key of the certificate. It is a functional unit to transmit to 20.

FIG. 10 is a block diagram showing a part of the functions of the management device 20 according to the embodiment of the present invention. The management device 20 further includes a receipt receiving unit 219, a terrestrial receiver authentication unit 220, an electronic signature verification unit 221, a hash value generation unit 222, a receipt authentication unit 223, and a receipt determination unit 224.

The receipt receiving unit 219 is a functional unit that receives the receipt, the electronic signature, the certificate of the ground receiver 40, and the public key of the certificate transmitted by the ground receiver 40. The terrestrial receiver authentication unit 220 authenticates the certificate of the terrestrial receiver 40 received by the receipt receiving unit 219 and the public key of the certificate by using the certificate of an external organization to authenticate the terrestrial receiver 40. It is a functional part to authenticate.

The electronic signature verification unit 221 is a functional unit that calculates a hash value from the electronic signature received by the receipt receiving unit 219. For example, the electronic signature verification unit 221 can decrypt the electronic signature received by the receipt receiving unit 219 using the public key of the certificate of the ground receiver 40, and calculate the hash value. The electronic signature verification unit 221 calculates a hash value from the electronic signature when the ground receiver 40 is authenticated.

The hash value generation unit 222 calculates a hash value from the receipt received by the receipt receiving unit 219 by using the hash function. This hash function is the same as the hash function used by the hash value generation unit 412 of the ground receiver 40. The hash value generation unit 222 calculates the hash value from the receipt when the ground receiver 40 is authenticated.

The receipt authentication unit 223 is a functional unit that compares the hash value calculated by the electronic signature verification unit 221 with the hash value generated by the hash value generation unit 222 and authenticates the receipt transmitted by the ground receiver 40. .. If these hash values are the same, the receipt authentication unit 223 determines that the receipt transmitted by the ground receiver 40 has not been tampered with in the transmission path.

The receipt determination unit 224 is a functional unit that determines whether or not the ground receiver 40 has received the receipt. The receipt determination unit 224 acquires the receipt transmitted to the ground receiver 40 from the receipt DB 213 and compares it with the receipt received by the receipt reception unit 219. If the contents of these receipts are the same, the receipt determination unit 224 determines that the ground receiver 40 has received the receipt. The receipt determination unit 224 determines whether or not the terrestrial receiver 40 has received the receipt when the receipt transmitted by the terrestrial receiver 40 is authenticated, that is, when it is determined that the receipt has not been tampered with. To do.

FIG. 11 is a sequence diagram showing a process executed in the satellite positioning system 1 according to the embodiment of the present invention. Hereinafter, the process executed after the ground receiver 40 receives the signal certificate from the management device 20 will be described with reference to FIG.

The terrestrial receiver 40 discloses a plurality of encrypted signal certificates and receipts transmitted by the management device 20, an encrypted common key, an electronic signature, a certificate of the management device 20, and the certificate. Upon receiving the key, the management device 20 is authenticated in step S34. When the management device 20 is authenticated, the terrestrial receiver 40 decodes the electronic signature in step S35 and calculates the hash value.

In step S36, the terrestrial receiver 40 generates a hash value from the plurality of encrypted signal certificates and receipts and the encrypted common key. In step S37, the terrestrial receiver 40 uses these hash values to authenticate the signal certificate, receipt, and common key. If the signal certificate, receipt, and common key transmitted by the management device 20 are authenticated, that is, if these data have not been tampered with, the terrestrial receiver 40 uses the encrypted common key in step S38. Decrypt.

In step S39, the terrestrial receiver 40 uses the decrypted common key to decrypt the plurality of encrypted signal certificates and receipts. In step S40, the terrestrial receiver 40 stores the decrypted plurality of signal certificates in the signal certificate DB 411. In step S41, the ground receiver 40 calculates a hash value from the decrypted receipt. In step S42, the terrestrial receiver 40 uses the private key of the certificate of the terrestrial receiver 40 to encrypt the hash value and generate an electronic signature. In step S43, the terrestrial receiver 40 transmits the decrypted receipt, the electronic signature, the certificate of the terrestrial receiver 40, and the public key of the certificate to the management device 20.

When the management device 20 receives the receipt, the electronic signature, the certificate of the ground receiver 40, and the public key of the certificate from the ground receiver 40, the management device 20 authenticates the ground receiver 40 in step S44. When the terrestrial receiver 40 is authenticated, the management device 20 decrypts the electronic signature and calculates the hash value by using the public key of the certificate of the terrestrial receiver 40 in step S45. In step S46, the management device 20 calculates the hash value from the receipt. In step S47, the management device 20 uses these hash values to authenticate the receipt received from the ground receiver 40. If the receipt received from the terrestrial receiver 40 is authenticated, that is, if the receipt has not been tampered with, the management device 20 determines in step S48 whether the terrestrial receiver 40 has received the receipt. ..

FIG. 12 is a block diagram showing a part of the functions of the ground receiver 40 according to the embodiment of the present invention. The ground receiver 40 includes a positioning signal receiving unit 415, a public key acquisition unit 416, an electronic signature verification unit 417, a hash value generation unit 418, a positioning signal authentication unit 419, a position calculation unit 420, and an authentication signal IDDB421. And further.

The positioning signal receiving unit 415 is a functional unit that receives signed positioning signals from a plurality of positioning satellites 30. When the positioning signal receiving unit 415 receives the signed positioning signal, the positioning signal ID, which is the identification information of the positioning signal, is added to the positioning signal.

The public key acquisition unit 416 acquires the public key of the signal certificate indicated by the signal certificate ID written in the free area of the navigation message of the signed positioning signal received by the positioning signal reception unit 415 from the signal certificate DB 411. It is a functional part to do.

The electronic signature verification unit 417 is a functional unit that calculates a hash value from the electronic signature written in the free area of the navigation message of the signed positioning signal received by the positioning signal receiving unit 415. For example, the electronic signature verification unit 417 can decrypt the electronic signature using the public key acquired by the public key acquisition unit 416 and calculate the hash value.

The hash value generation unit 418 is a functional unit that calculates a hash value from the signed positioning signal received by the positioning signal receiving unit 415 and the signal certificate ID of the signed positioning signal using a hash function. This hash function is the same as the hash function used by the hash value generation unit 203 of the management device 20.

The positioning signal authentication unit 419 authenticates the signed positioning signal received by the positioning signal receiving unit 415 using the hash value calculated by the electronic signature verification unit 417 from the electronic signature and the hash value calculated by the hash value generating unit 418. It is a functional part to do. When these hash values match, the positioning signal authentication unit 419 determines that the signed positioning signal is a genuine positioning signal guaranteed by the signal certificate issuing organization. The positioning signal authentication unit 419 stores a signed positioning signal in which these hash values match, that is, a positioning signal ID of the authenticated signed positioning signal in the authentication signal ID DB 421 as an authentication signal ID. In the authentication signal ID DB 421, only the positioning signal ID of the authenticated signed positioning signal among the positioning signals received from the plurality of positioning satellites is stored.

The position calculation unit 420 is a functional unit that calculates the position of the ground receiver 40 using the authenticated signature positioning signal. The position calculation unit 420 refers to the authentication signal IDDB 421, identifies signed positioning signals received from at least four or more different positioning satellites 30, and uses these signed positioning signals to connect the ground receiver 40 and each positioning satellite 30. Calculate the distance of. Then, the position calculation unit 420 calculates the position of the ground receiver 40 based on these distances, and the position time information indicating the calculated position and the time when the calculated position is calculated or when the signed positioning signal is received. To generate.

FIG. 13 is a sequence diagram showing a process executed in the satellite positioning system 1 according to the embodiment of the present invention. Hereinafter, with reference to FIG. 13, the process from the transmission of the signed positioning signal by the positioning satellite 30 to the generation of the position-time information by the terrestrial receiver 40 will be described.

In step S50, the positioning satellite 30 transmits the signed positioning signal to the ground receiver 40. When the ground receiver 40 receives the signed positioning signal from the positioning satellite 30, the ground receiver 40 adds the positioning signal ID to the positioning signal in step S51. In step S52, the ground receiver 40 acquires the public key of the signal certificate indicated by the signal certificate ID written in the signed positioning signal from the signal certificate DB 411.

In step S53, the ground receiver 40 uses the public key to decode the electronic signature written in the signed positioning signal and calculate the hash value. In step S54, the ground receiver 40 uses a hash function to calculate a hash value from the signed positioning signal and the signal certificate ID of the signed positioning signal. In step S54, the ground receiver 40 uses these hash values to authenticate the signed positioning signal. In step S54, the ground receiver 40 stores the positioning signal ID of the authenticated signature positioning signal in the authentication signal ID DB 421 as the authentication signal ID. In step S55, the position-time information of the ground receiver 40 is generated using the authenticated signed positioning signal.

FIG. 14 is a block diagram showing the main functions of the management device 20 and the ground receiver 40 according to the embodiment of the present invention. The management device 20 includes an encryption key generation unit 201, a signal certificate generation unit 202, a signed positioning signal generation unit 205, a signed positioning signal transmission unit 206, and a signal certificate transmission unit 218. The ground receiver 40 includes a signal certificate receiving unit 404, a positioning signal receiving unit 415, an electronic signature verification unit 417, a hash value generating unit 418, a positioning signal authentication unit 419, and a position calculating unit 420.

FIG. 15 shows a list of signal certificates provided by the management device 20 to the ground receiver 40. For example, in 2019, it is possible to provide four signal certificates indicated by signal certificates 2019-1 to 4, which are signal certificate IDs. In 2020, it is possible to provide four signal certificates indicated by signal certificates 2020-1 to 2020, which are signal certificate IDs. That is, the signal certificate provided to the terrestrial receiver 40 can be changed every year. The number of signal certificates provided by the management device 20 to the ground receiver 40 at one time can be arbitrarily determined. For example, in the embodiment in which the ground receiver 40 is installed in an automobile, it is preferable to provide four or more signal certificates in consideration of three years, which is the timing of the first vehicle inspection of the automobile.

As described above, the management device 20 generates a plurality of encryption keys corresponding to each of the plurality of signal certificates, and provides these encryption keys to the terrestrial receiver 40. Further, the management device 20 is an electron encrypted by using the identification information of one of the plurality of signal certificates and the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate. A signed positioning signal with a signature is transmitted to a plurality of positioning satellites 30.

When the ground receiver 40 receives the signed positioning signal from the plurality of positioning satellites 30, the identification information of the signal certificate attached to the signed positioning signal among the plurality of encryption keys provided by the management device 20 indicates. The hash value is calculated by decrypting the electronic signature attached to the signed positioning signal using the encryption key corresponding to the signal certificate. Next, the ground receiver 40 generates a hash value from the signed positioning signal and the identification information of the signal certificate attached to the signed positioning signal, and authenticates the signed positioning signal using these hash values. To do. The terrestrial receiver 40 uses the authenticated signed positioning signal to calculate the position of the terrestrial receiver 40.

As a result, in the satellite positioning system 1, since the ground receiver 40 calculates the position of its own device using the authenticated signature positioning signal, it is possible to prevent the calculation of illegal position information by the forged positioning signal. Can be done. This is particularly useful for billing systems that utilize location information such as road pricing.

Further, the management device 20 is an electron encrypted by using the identification information of one of the plurality of signal certificates and the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate. A signed positioning signal is generated by adding a positioning signal to the signature. The terrestrial receiver 40 acquires these encryption keys from the management device 20. Therefore, even if there is a problem with the security of one signal certificate, the security can be improved by changing the signal certificate used when generating the signed positioning signal to another signal certificate. it can.

Further, the management device 20 writes the identification information and the electronic signature of one signal certificate into a free area in the existing format of the positioning signal, for example, a free area of the navigation message of the positioning signal, thereby transmitting the signed positioning signal. Generate. As a result, it is not necessary to change the format of the conventional positioning signal, so that the present invention can be easily applied to the existing satellite positioning system.

Further, the management device 20 provides the ground receiver 40 with a plurality of signal certificates and encryption keys corresponding to the signal certificates when the ground receiver 40 that has transmitted the signal certificate request is authenticated. This makes it possible to prevent the signal certificate and the encryption key from being provided to the unauthorized terrestrial receiver 40.

Further, the management device 20 transmits a receipt indicating that the ground receiver 40 has received the plurality of signal certificates and the encryption key to the ground receiver 40 together with the signal certificate and the encryption key. When the terrestrial receiver 40 receives the signal certificate and the encryption key from the management device 20, it returns the receipt to the management device 20. The management device 20 determines whether or not the receipt transmitted to the terrestrial receiver 40 and the receipt received from the terrestrial receiver 40 are the same, so that the terrestrial receiver 40 receives the signal certificate and the encryption key. Determine if it has been received. As a result, the management device 20 can determine whether or not the ground receiver 40 has reliably received the signal certificate and the encryption key.

In the above example, the program can be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-temporary computer-readable media include magnetic recording media (eg, flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (eg, magneto-optical disks), CD-ROMs, CD-Rs, CD-Rs. / W, including semiconductor memory (for example, mask ROM, PROM (Programmable ROM), EPROM (Erasable PROM), flash ROM, RAM). The program may also be provided to the computer by various types of transient computer readable media. Examples of temporary computer-readable media include electrical, optical, and electromagnetic waves. The temporary computer-readable medium can supply the program to the computer via a wired communication path such as an electric wire and an optical fiber, or a wireless communication path.

The present invention is not limited to the above-described embodiment, and can be appropriately modified without departing from the spirit of the present invention. For example, in the above-described embodiment, the electronic signature is generated by encrypting the hash value with the private key, but in other embodiments, the electronic signature is digitally signed from the hash value by using an encryption method using an elliptic curve. May be generated.

1 Satellite positioning system 20 Management device 201 Cryptographic key generation unit 202 Signal certificate generation unit 205 Signed positioning signal generation unit 206 Signed positioning signal transmission unit 208 Ground receiver authentication unit 218 Signal certificate transmission unit 224 Receipt judgment unit 40 Ground Receiver 404 Signal certificate receiver 414 Receipt transmitter 415 Positioning signal receiver 417 Electronic signature verification unit 418 Hash value generation unit 419 Positioning signal authentication unit 420 Position calculation unit

Claims (7)

A management device that processes positioning signals transmitted by a plurality of positioning satellites and provides them to the plurality of positioning satellites.
Including a ground receiver that calculates the position of the own aircraft using a plurality of positioning signals received from the plurality of positioning satellites.
The management device is
A signal certificate generator that generates a plurality of signal certificates for the ground receiver to authenticate the positioning signal, and
An encryption key generator that generates a plurality of encryption keys corresponding to each of the plurality of signal certificates,
A signal certificate transmitter that transmits an encryption key corresponding to each of the plurality of signal certificates to the terrestrial receiver, and
The identification information of one of the plurality of signal certificates and the electronic signature encrypted by using the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate are positioned as a positioning signal. A signed positioning signal generator that is added to and generates a signed positioning signal,
It is provided with a signed positioning signal transmission unit that transmits the signed positioning signal to the plurality of positioning satellites.
The ground receiver
A signal certificate receiving unit that receives an encryption key corresponding to each of the plurality of signal certificates transmitted by the management device, and a signal certificate receiving unit.
A positioning signal receiving unit that receives the signed positioning signal from the plurality of positioning satellites,
Using the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate attached to the signed positioning signal, the electronic signature attached to the signed positioning signal is decrypted and the hash value is obtained. Electronic signature verification unit to calculate and
A hash value generator that generates a hash value from the signed positioning signal and the identification information of the signal certificate attached to the signed positioning signal.
A positioning signal authentication unit that authenticates the signed positioning signal using these hash values,
It includes a position calculation unit that calculates the position of the ground receiver using the authenticated positioning signal with the signature.
Satellite positioning system. The signed positioning signal generation unit generates the signed positioning signal by writing the identification information of the one signal certificate and the electronic signature in a free area of an existing format of the positioning signal. The satellite positioning system according to 1. The satellite positioning system according to claim 2, wherein the free area of the existing format of the positioning signal is a free area of the navigation message of the positioning signal. The management device is
It further includes a terrestrial receiver authentication unit that authenticates the terrestrial receiver.
When the terrestrial receiver is authenticated by the terrestrial receiver authentication unit, the signal certificate transmitter transmits an encryption key corresponding to each of the plurality of signal certificates to the terrestrial receiver. Item 3. The satellite positioning system according to any one of Items 1 to 3. The signal certificate transmitting unit of the management device sends a receipt indicating that the terrestrial receiver has received the encryption key corresponding to each of the plurality of signal certificates to the terrestrial receiver together with the encryption key. Send and
The terrestrial receiver further includes a receipt transmission unit that returns the receipt to the management device when the encryption key is received from the management device.
The management device determines whether or not the receipt transmitted to the terrestrial receiver and the receipt received from the terrestrial receiver are the same, so that the terrestrial receiver receives the encryption key. The satellite positioning system according to any one of claims 1 to 4, further comprising a receipt determination unit for determining whether or not the result has been made. A signal certificate receiving unit that receives an encryption key corresponding to each of a plurality of signal certificates for authenticating positioning signals from a plurality of positioning satellites.
The plurality of positioning satellites were encrypted using the identification information of one of the plurality of signal certificates and the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate. A positioning signal receiver that receives a signed positioning signal with an electronic signature attached,
A hash value is calculated by decoding the electronic signature attached to the signed positioning signal by using the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate attached to the positioning signal. Electronic signature verification department and
A hash value generator that generates a hash value from the signed positioning signal and the identification information of the signal certificate attached to the signed positioning signal.
A positioning signal authentication unit that authenticates the signed positioning signal using these hash values,
A terrestrial receiver including a position calculation unit that calculates the position of the own machine using the authenticated positioning signal with the signature. The step of receiving the encryption key corresponding to each of the multiple signal certificates for authenticating the positioning signals from multiple positioning satellites, and
The plurality of positioning satellites were encrypted using the identification information of one of the plurality of signal certificates and the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate. The step of receiving a signed positioning signal with an electronic signature attached,
The hash value is calculated by decoding the electronic signature attached to the signed positioning signal using the encryption key corresponding to the signal certificate indicated by the identification information of the signal certificate attached to the positioning signal. Steps and
A step of generating a hash value from the signed positioning signal and the identification information of the signal certificate attached to the signed positioning signal.
Using these hash values, the step of authenticating the signed positioning signal and
A position calculation method including the step of calculating the position of a ground receiver using the authenticated positioning signal with the signature.

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