METHOD FOR AUTHORIZING A CENTRAL UNIT CONNECTED TO PERIPHERAL UNITS USING A SECURE SERVER
The authentication process using a secure server and symmetrical encryption keys addresses the challenge of secure and efficient communication between central and peripheral units in vehicles, ensuring secure operations and reducing server load.
Patent Information
- Application Number
- FR2022003920
- Authority / Receiving Office
- FR · FR
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-04-27
- Publication Date
- 2025-01-31
- Estimated Expiration
- 2042-04-27
AI Technical Summary
Existing communication systems between central and peripheral units in vehicles face challenges in ensuring secure and efficient authentication for sensitive operations like reprogramming, while minimizing data exchange volume and preventing unauthorized access.
A bidirectional authentication process using a secure server to generate and share symmetrical encryption keys between a central unit and peripheral units, involving a series of encryption and decryption steps to verify the central unit's identity and ensure secure data transmission.
This process simplifies data handling on the server, enhances security by preventing unauthorized access, and allows secure, efficient execution of sensitive operations like reprogramming without overloading the server with large data exchanges.
Smart Images
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Abstract
Description
Title of the invention: METHOD FOR AUTHENTICATING A CENTRAL UNIT CONNECTED TO PERIPHERAL UNITS USING A SECURE SERVER Technical field
[0001] The present invention relates to a method for authenticating the rights of a central unit to communicate with peripheral units using a secure server connected by an Internet link, in order to carry out sensitive operations on these peripheral units, as well as units and a motor vehicle comprising devices implementing this method. Prior art
[0002] A type of method of communication between a system for monitoring the pressure of the tires of a motor vehicle, called "Tire pressure monitoring Systems" in English, "TMPS" for short, and intelligent equipment of a user of this vehicle, presented in particular by the document FR-A1-3084310, comprises a peripheral unit installed on each wheel of the vehicle measuring parameters such as the inflation pressure and the temperature of the tire, which are transmitted by radio frequency, in particular using the "Bluetooth" standard, to a central unit arranged in the vehicle receiving the information to process it and inform the driver or a repairer in order to alert in the event of a problem detected.
[0003] In particular, the wheel units periodically transmit information to the central unit, using a unique identifier of its own making it possible to identify the wheel concerned. Each wheel unit also has a wave receiver receiving signals from the central unit, to carry out diagnostic, configuration or learning operations of this wheel unit.
[0004] The method presents the use of ultra high frequency "UHF" waves, exceeding the gigahertz, making it possible to offer new applications such as exchange with equipment external to the vehicle, in particular a user's smartphone, called "Smartphone" in English.
[0005] Furthermore, generally speaking, in the case of a system carrying out radiofrequency exchanges between a central unit of a user or client, and peripheral units recording data, for example for these tire pressure monitoring systems, it may be necessary to carry out sensitive operations on these peripheral units, such as their reprogramming, using the Internet network and computer services managed by a remote server, called "cloud computing" in English.
[0006] Each unit has as an identifier a specific address stored in a physical memory for controlling access to the medium, called "Media Access Control" in English, "MAC" for short. The authentication of the user's central unit by the peripheral units to carry out sensitive operations on it such as reprogramming, poses problems for simply, without loading the server with exchanges of large volumes of data, ensuring a high level of security in order to avoid unwanted interventions by third parties such as hacking, and confidentiality of data exchanges.
[0007] The present invention aims in particular to avoid these problems of the prior art. Statement of the invention
[0008] To this end, it proposes a method for authenticating the rights of a central unit of a user to communicate bidirectionally with one or more peripheral units which transmit raw measurement data which they acquire, each central and peripheral unit having a specific identifier, this method using via the Internet network an external server device comprising at least one secure server, comprising a link by a secure connection between them in the case of several servers, and having in a database the identifier of the peripheral units, this method being remarkable in that it comprises the following successive steps: - in a first step the central unit uses its identifier and a password to be recognized by each peripheral unit which generates a shared symmetrical random encryption key, in parallel the central unit establishes a secure connection with the server device by authenticating itself so that it recognizes in its database the identifier of the peripheral unit concerned; - in a second step the server device generates a dynamic temporary session key; - in a third step the server device generates the same shared symmetric encryption key from the identifier of the peripheral unit, then performs a first encryption with this shared encryption key and with the dynamic temporary session key to form a first shared dynamic encryption key, then performs a second encryption using the identifier of the central unit, and the shared symmetric encryption key or the dynamic temporary session key to give encrypted central unit information which is proof of authentication; - in a fourth step the shared dynamic encryption key and the encrypted central unit information are transmitted to the central unit, which in turn transmits them to the peripheral unit; - the peripheral unit performs in a fifth step a reverse decryption of the first encryption performed by the server device in its third step, with its shared encryption key and the shared dynamic encryption key, to obtain the dynamic provisional session key; and - the peripheral unit carries out in parallel in a sixth step an encryption with its shared encryption key and the central unit identifier to give a second encrypted information, then compares this second encrypted information with the encrypted central unit information received to grant its authentication to this central unit if they coincide.
[0009] An advantage of the authentication method according to the invention is that it makes it possible to simplify the procedure for encrypting the source files stored in the server in order to avoid overloading this server, the encrypted files being created only once for all the peripheral units.
[0010] The rights authentication method according to the invention may further comprise one or more of the following characteristics, which may be combined with each other.
[0011] According to one embodiment, the peripheral unit performs in a following step an encryption of raw data to be transmitted with the dynamic temporary session key, to form encrypted data transmitted to the central unit, which in turn transmits them to the server device.
[0012] According to another embodiment, the peripheral unit performs in a following step an encryption of the raw data to be transmitted with the shared dynamic encryption key, to form encrypted data transmitted to the central unit which then performs a decryption to obtain the raw data, with the shared dynamic encryption key that this central unit has kept in memory.
[0013] The server device may comprise a single server which is secure, carrying out the second step of generating the dynamic temporary session key, and the third step of generating the shared dynamic encryption key and then the encrypted central unit information forming the proof of authentication.
[0014] Alternatively, the server device may comprise a first server having the identifier of the peripheral unit in a database, and comprise the secure server having the shared encryption key in a database.
[0015] In this case, advantageously the first server carries out the second step of generating the dynamic temporary session key, then transmits this dynamic temporary session key and the identifier of the central unit to the secure server.
[0016] Furthermore, advantageously the secure server then carries out the third step of generating the shared dynamic encryption key, then the encrypted central unit information forming the proof of authentication.
[0017] The invention also relates to a system comprising a central unit, and peripheral units carrying out measurements forming raw data, linked by radio frequency to each other, remarkable in that it comprises devices implementing a method comprising any one of the preceding characteristics.
[0018] The invention further relates to a motor vehicle comprising a central unit, and peripheral units carrying out measurements on the tires of the wheels of this vehicle forming raw data, remarkable in that it comprises devices implementing a method comprising any one of the preceding characteristics. Brief description of the drawings
[0019] [Fig-1]: [Fig.l] is a functional diagram showing a method according to the invention authentication of a central unit located in a motor vehicle, connected to peripheral units fixed to the wheels of the vehicle, using two servers;
[0020] [Fig.2]: [Fig.2] is a functional diagram showing the method using a single server; and
[0021] [Fig.3]: [Fig.3] is a functional diagram showing the process using a single server, according to a variant. Description of the embodiments
[0022] [Fig.l] presents in a motor vehicle a central unit 2 forming a client having a central unit identifier 4, and on each wheel a peripheral unit 6 comprising pressure and temperature sensors of the tire of the wheel, having a peripheral unit identifier 8 and a specific shared symmetric encryption key 10 which are recorded during the manufacture of this unit. The central unit 2 and the peripheral units 6 communicate with each other using in particular the “Bluetooth®” standard.
[0023] An Internet network 14 using a radio frequency link makes it possible to connect the central unit 2 to an external server device 11 comprising a first server 5 having in a database the identifier of the peripheral unit 8, and a second secure server 12 having in a database the shared symmetric encryption key 10 of this peripheral unit.
[0024] In particular, the first server 5 may be that of a vehicle fleet manager or of the automobile manufacturer wishing to monitor its vehicles put into circulation, receiving information directly from the central unit 2, to exchange with the second secure server 12 which may be that of the tire manufacturer wishing to monitor the evolution of its manufactured tires.
[0025] The authentication method of the central unit 2 allowing exchanges with the peripheral units 6 and carrying out sensitive operations on them, comprises a first step 20 of using the identifier 4 of the central unit 2 and a password password to be recognized by the specific peripheral unit 6, and accept the connection.
[0026] In parallel, the central unit 2 is connected by a secure link 14 to the first server 5 to use its identifier 4 and that 8 of the peripheral unit 6, so that it recognizes in its database the identifier of the specific unit concerned 6. Advantageously, a link by secure hypertext transfer protocol, called "HyperText Transfer Protocol Secure" in English, "HTTPS" for short, is used, taking for example the identifier 4 of the central unit 2 and a password.
[0027] In a second step 22 the first server 5 generates a dynamic temporary session key 13, which is transmitted with the identifier 4 of the central unit 2 to the second server 12.
[0028] In a third step 24 the second server 12 generates the same shared symmetric encryption key 10 from the identifier 8 of the peripheral unit 6, then performs a first encryption with this shared symmetric encryption key 10 and with the dynamic provisional session key 13, to form a first dynamic encryption key 25. The second server 12 then performs a second encryption with the identifier 4 of the central unit 2 and the shared symmetric encryption key 10, to give encrypted central unit information 32 which constitutes proof of authentication of the central unit 2.
[0029] In a fourth step 26 the second server 12 transmits the dynamic encryption key 25 and the encrypted central unit information 32 to the first server 5 which in turn transmits them to the central unit 2, this central unit then transmitting them to the peripheral unit 6.
[0030] In a fifth step 28 the peripheral unit 6 performs a reverse decryption of the first encryption performed by the second server 12 in the third step 24, using its shared encryption key 10 and the dynamic encryption key 25 to obtain the dynamic provisional session key 13.
[0031] In a sixth step 30, the peripheral unit 6 performs, in parallel with the fifth step 28, an encryption using the identifier 4 of the central unit 2 and its shared encryption key 10 to give a second encrypted information 42. The peripheral unit 6 then compares this second encrypted information 42 with the encrypted information of the central unit 32 coming from the second server 12, in order, if they coincide, to grant its authentication 34 to the central unit 4.
[0032] The peripheral unit 6 performs in a seventh following step 38 an encryption of the raw data to be transmitted D0 constituted by measurements carried out on the tire, with the dynamic provisional session key 13, to form encrypted data K(D0) transmitted in step 36 to the central unit 2 which transmits them in turn to the first server 5. In a following step 46 the first server 5 performs with the dynamic temporary session key 13 a decryption of the encrypted data K(D0) to obtain the raw data DO.
[0033] With this method, the central unit 2 can subsequently give this proof again to the peripheral unit 6 without the help of the server 12, only during the same communication session with this peripheral unit. In this way, an external person wanting to hack the system by trying to connect during the next session, will not be able to give this proof again and will not be able to pretend to be the client.
[0034] [Fig.2] shows a similar method for an external server device 11 comprising a single secure server 12 having the identifier 8 of the peripheral unit 6 and the corresponding shared symmetric encryption key 10.
[0035] In this case the single secure server 12 carries out the second step 22 which generates the dynamic temporary session key 13.
[0036] The server 12 then carries out the third step 24 comprising the first encryption which uses the shared symmetric encryption key 10 and the dynamic temporary session key 13 to form the first dynamic encryption key 25, then the second encryption which uses the identifier 4 of the central unit 2 and the dynamic temporary session key 13 to give the encrypted central unit information 32 constituting the proof of authentication of the central unit 2.
[0037] We then have, as for [Fig. 1], the transmission of the encrypted information from central unit 32 to central unit 2 then to peripheral unit 6, this peripheral unit carrying out in the same way the fifth step 28 and the sixth step 30 of validation of the authentication, then the seventh step 38 of encryption with the dynamic provisional session key 13 and transmission of the raw data D0 to central unit 2 then to the secure server 12 which decrypts them.
[0038] [Fig.3] shows a method similar to that of [Fig.1] with two servers or [Fig.2] with a single server, comprising as a difference after the authentication of the central unit 2, the operation 38 of encryption of the raw data D0 carried out by the peripheral unit 6 which uses the first dynamic encryption key 25 instead of the dynamic provisional session key 13.
[0039] The central unit 2, which has retained the first dynamic encryption key 25, can then itself carry out the operation of decrypting the encrypted data K(D0) to obtain the raw data D0, using this first encryption key.
[0040] Advantageously, the encryptions and decryptions are carried out with the “AES128” standard, for “Advanced Encryption Standard” in English, or advanced encryption standard.
[0041] The authentication method according to the invention is particularly suitable for checking the tires of a motor vehicle, in order to signal to the user or a repairer of failures or to prevent them. It also allows car manufacturers or tire manufacturers to receive information on an external server to ensure monitoring of their products and to improve quality.
Claims
1. Claims Method for authenticating the rights of a central unit of a user (2) to communicate bidirectionally by radio frequency with one or more peripheral units (6) fixed on the wheels of a motor vehicle which transmit raw measurement data (DO) consisting of measurements carried out on the tires of the vehicle which they acquire, each central unit (2) and peripheral unit (6) having a specific identifier (4, 8), this method using via the Internet network (14) an external server device (11) comprising at least one secure server (12), comprising a secure connection between them in the case of several servers (5, 12), and having in a database the identifier (8) of the peripheral units (6), characterized in that it comprises the following successive steps: - in a first step (20) the central unit (2) uses its identifier (4) and a password to be recognized by each peripheral unit (6) which generates a shared symmetric random encryption key (10), in parallel the central unit (2) establishes a secure link (14) with the server device (11) by authenticating itself so that it recognizes in its database the identifier (8) of the peripheral unit concerned (6); - in a second step (22) the server device (11) generates a dynamic temporary session key (13); - in a third step (24) the server device (11) generates the same shared symmetric encryption key (10) from the identifier (8) of the peripheral unit (6), then performs a first encryption with this shared encryption key (10) and with the dynamic temporary session key (13) to form a first shared dynamic encryption key (25), then performs a second encryption using the identifier (4) of the central unit (2), and the shared symmetric encryption key (10) or the dynamic temporary session key (13) to give encrypted central unit information (32) which is a proof of authentication; - in a fourth step (26) the shared dynamic encryption key (25) and the encrypted central unit information (32) are transmitted to the central unit (2), which in turn transmits them to the peripheral unit (6) - the peripheral unit (6) performs in a fifth step (28) a reverse decryption of the first encryption performed by the server device (11) in its third step (24), with its shared encryption key (10) and the shared dynamic encryption key (25), to obtain the dynamic provisional session key (13); and - the peripheral unit (6) performs in parallel in a sixth step (30) an encryption with its shared encryption key (10) and the central unit identifier (4) to give a second encrypted information (42), then compares this second encrypted information (42) with the received encrypted central unit information (32) to, if they coincide, grant its authentication (34) to this central unit (2).
2. Method according to claim 1, characterized in that the peripheral unit (6) carries out in a following step (38) an encryption of the raw data to be transmitted (DO) with the dynamic temporary session key (13), to form encrypted data (K(D0)) transmitted (36) to the central unit (2), which in turn transmits them to the server device (11).
3. Method according to claim 1, characterized in that the peripheral unit (6) carries out in a following step (38) an encryption of the raw data to be transmitted (DO) with the shared dynamic encryption key (25), to form encrypted data (K(D0)) transmitted to the central unit (2) which then carries out a decryption (46) to obtain the raw data (DO), with the shared dynamic encryption key (25) that this central unit (2) has kept in memory.
4. Method according to any one of the preceding claims, characterized in that the server device (11) comprises a single server which is secure (12), carrying out the second step (22) of generating the dynamic provisional session key (13), and the third step (24) of generating the shared dynamic encryption key (25) then the encrypted central unit information (32) forming the proof of authentication.
5. Method according to any one of claims 1 to 3, characterized in that the server device (11) comprises a first server (5) having in a database the identifier (8) of the peripheral unit (6), and comprises the secure server (12) having in a database the shared encryption key (10).
6. Method according to claim 5, characterized in that the first server (5) carries out the second step (22) of generating the key of dynamic temporary session (13), then transmits this dynamic temporary session key (13) and the identifier (4) of the central unit (2) to the secure server (12).
7. Method according to claim 6, characterized in that the secure server (12) then carries out the third step (24) of generating the shared dynamic encryption key (25), then the encrypted central unit information (32) forming the proof of authentication (32).
8. System comprising a central unit (2), and peripheral units (6) fixed on the wheels of a motor vehicle carrying out measurements on the tires of the wheels of the vehicle forming raw data (DO), linked by radio frequency to each other, characterized in that it comprises devices implementing a method according to any one of the preceding claims.
9. Motor vehicle comprising a central unit (2), and peripheral units (6) fixed to the wheels of the motor vehicle carrying out measurements on the tires of the wheels of this vehicle forming raw data (DO), characterized in that it comprises devices implementing a method according to any one of claims 1 to 7.