EP1186736A1 - Process for securing the communication in a hands-free access system - Google Patents

Process for securing the communication in a hands-free access system Download PDF

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Publication number
EP1186736A1
EP1186736A1 EP01121540A EP01121540A EP1186736A1 EP 1186736 A1 EP1186736 A1 EP 1186736A1 EP 01121540 A EP01121540 A EP 01121540A EP 01121540 A EP01121540 A EP 01121540A EP 1186736 A1 EP1186736 A1 EP 1186736A1
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Prior art keywords
signal
recognition device
identification
reception
vehicle
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EP01121540A
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German (de)
French (fr)
Inventor
Alain Gascher
Jean-Jacques Avenel
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Valeo Comfort and Driving Assistance SAS
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Valeo Electronique SA
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    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C9/00—Individual registration on entry or exit
    • G07C9/20—Individual registration on entry or exit involving the use of a pass
    • G07C9/28—Individual registration on entry or exit involving the use of a pass the pass enabling tracking or indicating presence

Definitions

  • the invention relates to a method for securing a communication. between a recognition device and an identification device capable of communicate with the recognition device so that the recognition device can authenticate the identification unit for control the unlocking of the sashes of a vehicle and / or authorize the starting a vehicle, in which authentication is based on a evaluation by the reaction time recognition device corresponding to the time that elapses between the emission by the recognition of a first signal towards the identification body and the reception by the recognition device of a second transmitted signal by the identification body in response to the first signal.
  • bidirectional communication in the form data exchange between the recognition device and the organ the purpose of identification is generally that the recognition device authenticates the identification body on the one hand by verifying its signature and on the other hand by evaluating a reaction time in the exchange of data.
  • the evaluation of a reaction time aims to detect a hacking by repeater: if a first pirate, equipped with a first transmitter-receiver relay, located near the vehicle, is in connection with a second hacker, equipped with a second transmitter-receiver relay located near the bearer of the identification device, the two hackers are able to trigger a data exchange between the recognition device and the identification unit, without the knowledge of the holder of the identification unit.
  • the repeater thus constituted necessarily increases the time of reaction in the exchange of data between the recognition device and the identification body.
  • the first signals and the second signals are pulses, and the device recognition assesses reaction time based on one or more several measurements of the time interval between the emission of a first impulse signal and receiving the second impulse signal corresponding.
  • the recognition device detects the moment of reception of a second impulse signal taking into account the moment when the rising edge of the second impulse signal received reaches a certain reference threshold value.
  • the defect of such a solution is that the evaluation of the reaction time is influenced by the reception level of the second impulse signals by the recognition device: the lower this level of reception, the more the evaluation of the reaction time is distorted.
  • the object of the invention is to remedy this drawback.
  • the subject of the invention is a method for securing a communication between a recognition device and an organ identification capable of communicating with the device for recognizing so that the recognition device can authenticate the organ of identification to control the unlocking of a vehicle's sashes and / or authorize the starting of a vehicle, in which authentication is based on an evaluation by the time recognition device reaction corresponding to the time which elapses between the emission by the device for recognizing a first signal towards the organ identification and receipt by the recognition device of a second signal from the identification body in response to the first signal, characterized in that each second signal is amplified by the device recognition to have a maximum amplitude corresponding to a maximum reference amplitude, and in that the evaluation of the time of reaction is based on measuring a time interval between the instant of emission of a first signal and the instant at which the second signal corresponding amplified reaches a reference threshold value.
  • Such a method makes the accuracy of the evaluation of the reaction time is not conditioned by the vagaries of the transmission between the organ identification and recognition device, particularly in the case of a system where the pulses have a slow rise time introducing an additional difficulty for hacking. Indeed, it will introduce a delay all the longer as it will have to detect an impulse with a time slow climb. Pulse detection is made necessary for the synchronization of hacking cases, even if they are content with copy the spectrum.
  • the identification organ transmits in the direction of the recognition device a calibration signal so that the device recognition adjusts the amplification according to a reception level of said calibration signal, and secondly the device for recognition issues towards the identification body several first successive signals to which the identification body responds with the emission of second corresponding signals, each second signal being emitted upon reception of the first corresponding signal, a process is obtained which performs automatic gain control for each authentication of the identification body by the recognition device, for a cost of reduced manufacturing.
  • Figure 1 is a schematic representation of an access system hands free.
  • Figure 2 is a graphical representation of the influence of the level of reception on the accuracy of the evaluation of a reaction time.
  • Figure 3 is a schematic representation in the form of a flow chart of the method according to the invention.
  • Figure 1 shows schematically a recognition device DR and an OI identification unit for a so-called “hands-free” access system.
  • the DR recognition device which is positioned in the vehicle includes an ADR transmitter and receiver antenna coupled to a MD modulator-demodulator which communicates with an MC microcontroller.
  • the identification unit comprises an AOI transmitting antenna which is coupled with an MG management module.
  • the identification body and the recognition device can exchange information by radiofrequency transmission so as to implement a protocol of identification of the identification body by the recognition device.
  • Such a protocol generally includes an evaluation of the reaction time corresponding to the time which elapses between the emission of a first signal by the recognition device and the reception by the device recognition of a second signal emitted by the identification body in response to the first signal, so as to detect the presence of a device of hacking which necessarily increases the reaction time.
  • the signals exchanged during such a protocol identification signals are generally impulse signals, such so that the recognition device successively transmits several first signals which are timing tops, and the organ identification responds to each synchronization signal by issuing a second corresponding signal which is a response bit.
  • the identification unit must for example provide the series of bits 1011 for identify himself to the recognition device, he will issue a impulse upon receipt of a first synchronization signal sent by the recognition device, do not send anything after receiving a second synchronization signal, send a pulse after reception of the third synchronization signal, and send a pulse after reception of the fourth synchronization top. So the recognition device can reconstruct the series of bits sent by the identification unit, and know the reaction time by evaluating the time between the program synchronization signal and reception of the pulse emitted by the device recognition, for the first, third and fourth response bits.
  • the reception level of the transmitted pulses by the identification organ is conditioned by several parameters such as the position of the AOI antenna of the identification unit with respect to the ADR antenna of the recognition device, or by the electromagnetic disturbances introduced by the environment. So the level of reception of signals emitted by the identification unit is different for each data exchange, which more or less distorts the evaluation of the reaction time of the identification body.
  • a second impulse signal SS as it can be received by the recognition device has been represented graphically, as well as the reference threshold value VSR corresponding to the threshold for detection of a pulse by the recognition device
  • the evaluation of the instant of reception of the second impulse signal depends on the level of reception of this signal. Indeed, if the reception level is high, as for the IH form, the threshold value VSR is reached at an instant t 1 , while for the IB form corresponding to a lower reception level, the threshold value is reached at an instant t 2 , with t 2 > t 1 .
  • the evaluation of a reaction time is all the more false the lower the reception level.
  • This amplified signal SSA is the signal received at a high or low level which has been amplified so that its maximum amplitude corresponds to a maximum amplitude of AMR reference, thus, this amplified signal SSA corresponds just as well to the amplification of the second signal SS that it was received at a high level IH, or at a low level IB.
  • time t 0 at which the second amplified signal SSA reaches the reference threshold value is then independent of the level of reception of the second signal by the recognition device.
  • FIG 3 there is shown in the form of a flowchart a identification protocol, making it possible to see in particular how the amplification level to be applied by the recognition device to a series of second signals can be chosen.
  • the device for DR recognition mounted in the vehicle emits a code called question code towards the identification body.
  • This first broadcast corresponding to the start of the protocol could for example be triggered by the support of the vehicle driver on a button on a door.
  • This question code is intended to be processed by the identification body which may be an identifier located in the driver's pocket, so that the identification body subsequently emits a response code towards the recognition device so that the latter recognizes the signature of the identification body.
  • the identification unit emits a standard signal which may by example be a long-lasting pulse so that the recognition device evaluates at 30 the level of reception of signals emitted by the identification unit and deduce the amplification therefrom apply.
  • Each receiver in the identifier or the vehicle
  • Two types of corrections can be implemented in 40. The first consists in measuring the level and tabulating a delay or an advance depending on the level. For example a tension analog (which reflects the level) can be converted into a byte to get a tabulated advance or delay in the precontroller. The second is to correct the level so that the signal is of constant amplitude before the threshold (fig. 2). This implies an automatic gain correction.
  • the recognition device will emit the first signals which are synchronization tops so that the identification organ emits corresponding second signals in response so as to transmit the response bit sequence to the recognition device.
  • These second signals could be an impulse emitted upon reception of the top of corresponding synchronization if the bit to be transmitted is 1, and none pulse if the bit to be transmitted is 0.
  • the microcontroller will be able to record the moments when the tops of synchronization and the times when the second amplified signals are received Corresponding SSA, in order to calculate in 60 the reaction time of the identification body. Finally, the evaluated reaction time will be judged satisfactory if it is less than a reference reaction time, and too much important if it is greater than this reference reaction time.
  • the method according to the invention adapts to a protocol standard identification without requiring significant modifications to the protocol, and therefore allows an improvement in the evaluation accuracy of the reaction time for a very low manufacturing cost.

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  • General Physics & Mathematics (AREA)
  • Lock And Its Accessories (AREA)

Abstract

Method in which a recognition device in the vehicle sends a first signal to an identification device. The latter sends a second signal back. The signal is amplified so that it has maximum amplitude corresponding to a reference maximum amplitude. The evaluation of the reaction time of the identification device is based on measurement of the time interval elapsing between emission of the first signal and the instant at which the second amplified signal reaches the threshold reference amplitude. An Independent claim is made for a securitization method in which the signal level is measured and a time correction tabulated by a microcontroller.

Description

L'invention concerne un procédé de sécurisation d'une communication entre un dispositif de reconnaissance et un organe d'identification apte à communiquer avec le dispositif de reconnaissance de manière à ce que le dispositif de reconnaissance puisse authentifier l'organe d'identification pour commander le déverrouillage d'ouvrants d'un véhicule et/ou autoriser le démarrage d'un véhicule, dans lequel l'authentification est basée sur une évaluation par le dispositif de reconnaissance d'un temps de réaction correspondant au temps qui s'écoule entre l'émission par le dispositif de reconnaissance d'un premier signal en direction de l'organe d'identification et la réception par le dispositif de reconnaissance d'un second signal émis par l'organe d'identification en réponse au premier signal.The invention relates to a method for securing a communication. between a recognition device and an identification device capable of communicate with the recognition device so that the recognition device can authenticate the identification unit for control the unlocking of the sashes of a vehicle and / or authorize the starting a vehicle, in which authentication is based on a evaluation by the reaction time recognition device corresponding to the time that elapses between the emission by the recognition of a first signal towards the identification body and the reception by the recognition device of a second transmitted signal by the identification body in response to the first signal.

Dans un tel système, la communication bidirectionnelle sous forme d'échange de données entre le dispositif de reconnaissance et l'organe d'identification a généralement pour but que le dispositif de reconnaissance authentifie l'organe d'identification d'une part en vérifiant sa signature et d'autre part en évaluant un temps de réaction dans l'échange de données.In such a system, bidirectional communication in the form data exchange between the recognition device and the organ the purpose of identification is generally that the recognition device authenticates the identification body on the one hand by verifying its signature and on the other hand by evaluating a reaction time in the exchange of data.

L'évaluation d'un temps de réaction a pour objectif de détecter un piratage par répéteur: si un premier pirate, muni d'un premier relais émetteur-récepteur, situé à proximité du véhicule, est en relation avec un second pirate, muni d'un second relais émetteur-récepteur situé à proximité du porteur de l'organe d'identification, les- deux pirates sont en mesure de déclencher un échange de données entre le dispositif de reconnaissance et l'organe d'identification, à l'insu du porteur de l'organe d'identification. Cela étant, le répéteur ainsi constitué augmente nécessairement le temps de réaction dans l'échange de données entre le dispositif de reconnaissance et l'organe d'identification. En évaluant un temps de réaction, le dispositif de reconnaissance peut donc détecter un piratage par répéteur, et par-là même, ne pas commander le déverrouillage des ouvrants du véhicule, et/ou ne pas commander le démarrage du véhicule.The evaluation of a reaction time aims to detect a hacking by repeater: if a first pirate, equipped with a first transmitter-receiver relay, located near the vehicle, is in connection with a second hacker, equipped with a second transmitter-receiver relay located near the bearer of the identification device, the two hackers are able to trigger a data exchange between the recognition device and the identification unit, without the knowledge of the holder of the identification unit. it being, the repeater thus constituted necessarily increases the time of reaction in the exchange of data between the recognition device and the identification body. By evaluating a reaction time, the recognition can therefore detect a hack by repeater, and by that even, do not order the unlocking of the vehicle's doors, and / or do not order the vehicle to start.

Pour qu'un tel système ait un degré de sécurité satisfaisant, il faut entre autres qu'il soit capable d'évaluer avec suffisamment de précision un tel temps de réaction dans l'échange de données. Typiquement, les premiers signaux et les seconds signaux sont des impulsions, et le dispositif de reconnaissance évalue le temps de réaction en se basant sur une ou plusieurs mesures de l'intervalle de temps qui sépare l'émission d'un premier signal impulsionnel et la réception du second signal impulsionnel correspondant.For such a system to have a satisfactory degree of security, it is necessary between others that he is able to accurately assess such a reaction time in data exchange. Typically, the first signals and the second signals are pulses, and the device recognition assesses reaction time based on one or more several measurements of the time interval between the emission of a first impulse signal and receiving the second impulse signal corresponding.

Plus particulièrement, le dispositif de reconnaissance détecte l'instant de réception d'un second signal impulsionnel en prenant en compte l'instant où le front montant du second signal impulsionnel reçu atteint une certaine valeur seuil de référence.More particularly, the recognition device detects the moment of reception of a second impulse signal taking into account the moment when the rising edge of the second impulse signal received reaches a certain reference threshold value.

Le défaut d'une telle solution est que l'évaluation du temps de réaction est influencée par le niveau de réception des seconds signaux impulsionnels par le dispositif de reconnaissance : plus ce niveau de réception est faible, plus l'évaluation du temps de réaction est faussée.The defect of such a solution is that the evaluation of the reaction time is influenced by the reception level of the second impulse signals by the recognition device: the lower this level of reception, the more the evaluation of the reaction time is distorted.

Le but de l'invention est de remédier à cet inconvénient.The object of the invention is to remedy this drawback.

A cet effet, l'invention a pour objet un procédé de sécurisation d'une communication entre un dispositif de reconnaissance et un organe d'identification apte à communiquer avec le dispositif de reconnaissance de manière à ce que le dispositif de reconnaissance puisse authentifier l'organe d'identification pour commander le déverrouillage d'ouvrants d'un véhicule et/ou autoriser le démarrage d'un véhicule, dans lequel l'authentification est basée sur une évaluation par le dispositif de reconnaissance d'un temps de réaction correspondant au temps qui s'écoule entre l'émission par le dispositif de reconnaissance d'un premier signal en direction de l'organe d'identification et la réception par le dispositif de reconnaissance d'un second signal émis par l'organe d'identification en réponse au premier signal, caractérisé en ce chaque second signal est amplifié par le dispositif de reconnaissance pour avoir une amplitude maximale correspondant à une amplitude maximale de référence, et en ce que l'évaluation du temps de réaction est basée sur la mesure d'un intervalle de temps s'écoulant entre l'instant d'émission d'un premier signal et l'instant auquel le second signal amplifié correspondant atteint une valeur seuil de référence.To this end, the subject of the invention is a method for securing a communication between a recognition device and an organ identification capable of communicating with the device for recognizing so that the recognition device can authenticate the organ of identification to control the unlocking of a vehicle's sashes and / or authorize the starting of a vehicle, in which authentication is based on an evaluation by the time recognition device reaction corresponding to the time which elapses between the emission by the device for recognizing a first signal towards the organ identification and receipt by the recognition device of a second signal from the identification body in response to the first signal, characterized in that each second signal is amplified by the device recognition to have a maximum amplitude corresponding to a maximum reference amplitude, and in that the evaluation of the time of reaction is based on measuring a time interval between the instant of emission of a first signal and the instant at which the second signal corresponding amplified reaches a reference threshold value.

Un tel procédé fait que la précision de l'évaluation du temps de réaction n'est pas conditionnée par les aléas de la transmission entre l'organe d'identification et le dispositif de reconnaissance, en particulier dans le cas d'un système où les impulsions ont un temps de montée lent introduisant une difficulté supplémentaire pour le piratage. En effet, celui-ci introduira un retard d'autant plus long qu'il aura à détecter une impulsion avec un temps de montée lent. La détection de l'impulsion est rendue nécessaire pour la synchronisation des valises de piratage, même si celles-ci se contentent de recopier le spectre.Such a method makes the accuracy of the evaluation of the reaction time is not conditioned by the vagaries of the transmission between the organ identification and recognition device, particularly in the case of a system where the pulses have a slow rise time introducing an additional difficulty for hacking. Indeed, it will introduce a delay all the longer as it will have to detect an impulse with a time slow climb. Pulse detection is made necessary for the synchronization of hacking cases, even if they are content with copy the spectrum.

Selon un mode de mise en oeuvre particulier du procédé selon l'invention dans lequel dans un premier temps l'organe d'identification émet en direction du dispositif de reconnaissance un signal d'étalonnage pour que le dispositif de reconnaissance ajuste l'amplification en fonction d'un niveau de réception dudit signal d'étalonnage, et dans un second temps le dispositif de reconnaissance émet en direction de l'organe d'identification plusieurs premiers signaux successifs auxquels l'organe d'identification répond par l'émission de seconds signaux correspondants, chaque second signal étant émis dès réception du premier signal correspondant, on obtient un procédé qui réalise un contrôle automatique de gain pour chaque authentification de l'organe d'identification par le dispositif de reconnaissance, pour un coût de fabrication réduit.According to a particular implementation of the method according to the invention in which initially the identification organ transmits in the direction of the recognition device a calibration signal so that the device recognition adjusts the amplification according to a reception level of said calibration signal, and secondly the device for recognition issues towards the identification body several first successive signals to which the identification body responds with the emission of second corresponding signals, each second signal being emitted upon reception of the first corresponding signal, a process is obtained which performs automatic gain control for each authentication of the identification body by the recognition device, for a cost of reduced manufacturing.

Le procédé selon l'invention sera maintenant décrit plus en détail, et en référence aux dessins annexés qui en illustrent une forme de mise en oeuvre à titre d'exemple non limitatif.The method according to the invention will now be described in more detail, and in reference to the accompanying drawings which illustrate a form of implementation thereof by way of nonlimiting example.

La figure 1 est une représentation schématique d'un système d'accès mains libres.Figure 1 is a schematic representation of an access system hands free.

La figure 2 est une représentation graphique de l'influence du niveau de réception sur la précision de l'évaluation d'un temps de réaction.Figure 2 is a graphical representation of the influence of the level of reception on the accuracy of the evaluation of a reaction time.

La figure 3 est une représentation schématique sous la forme d'un organigramme du procédé selon l'invention.Figure 3 is a schematic representation in the form of a flow chart of the method according to the invention.

La figure 1 montre de façon schématique un dispositif de reconnaissance DR et un organe d'identification OI d'un système d'accès dit « mains libres ». Le dispositif de reconnaissance DR qui est positionné dans le véhicule comprend une antenne émettrice et réceptrice ADR couplée à un modulateur-démodulateur MD qui communique avec un microcontrôleur MC. L'organe d'identification comprend une antenne émettrice AOI qui est couplée à un module de gestion MG. Ainsi, l'organe d'identification et le dispositif de reconnaissance peuvent échanger des informations par transmission radiofréquence de manière à mettre en oeuvre un protocole d'identification de l'organe d'identification par le dispositif de reconnaissance. Un tel protocole inclut généralement une évaluation du temps de réaction correspondant au temps qui s'écoule entre l'émission d'un premier signal par le dispositif de reconnaissance et la réception par le dispositif de reconnaissance d'un second signal émis par l'organe d'identification en réponse au premier signal, de manière à détecter la présence d'un dispositif de piratage qui augmente nécessairement le temps de réaction. Plus particulièrement, les signaux échangés au cours d'un tel protocole d'identification sont généralement des signaux impulsionnels, de telle manière que le dispositif de reconnaissance émet successivement plusieurs premiers signaux qui sont des tops de synchronisation, et l'organe d'identification répond à chaque top de synchronisation par l'émission d'un second signal correspondant qui est un bit réponse. Plus concrètement, si l'organe d'identification doit par exemple fournir la suite de bits 1011 pour s'identifier auprès du dispositif de reconnaissance, il va émettre une impulsion dès réception d'un premier top de synchronisation émis par le dispositif de reconnaissance, ne rien émettre après réception d'un second top de synchronisation, émettre une impulsion après réception du troisième top de synchronisation, et émettre une impulsion après réception du quatrième top de synchronisation. Ainsi, le dispositif de reconnaissance pourra reconstituer la suite de bits émis par l'organe d'identification, et connaítre le temps de réaction en évaluant le temps qui a séparé l'émission du top de synchronisation et la réception de l'impulsion émise par l'organe de reconnaissance, pour le premier, le troisième et le quatrième bit réponse. Dans un tel système d'accès, le niveau de réception des impulsions émises par l'organe d'identification est conditionné par plusieurs paramètres tels que la position de l'antenne AOI de l'organe d'identification par rapport à l'antenne ADR du dispositif de reconnaissance, ou encore par les perturbations électromagnétiques introduites par l'environnement. Ainsi, le niveau de réception des signaux émis par l'organe d'identification est différent pour chaque échange de données, ce qui fausse plus ou moins l'évaluation du temps de réaction de l'organe d'identification.Figure 1 shows schematically a recognition device DR and an OI identification unit for a so-called “hands-free” access system. The DR recognition device which is positioned in the vehicle includes an ADR transmitter and receiver antenna coupled to a MD modulator-demodulator which communicates with an MC microcontroller. The identification unit comprises an AOI transmitting antenna which is coupled with an MG management module. Thus, the identification body and the recognition device can exchange information by radiofrequency transmission so as to implement a protocol of identification of the identification body by the recognition device. Such a protocol generally includes an evaluation of the reaction time corresponding to the time which elapses between the emission of a first signal by the recognition device and the reception by the device recognition of a second signal emitted by the identification body in response to the first signal, so as to detect the presence of a device of hacking which necessarily increases the reaction time. More particularly, the signals exchanged during such a protocol identification signals are generally impulse signals, such so that the recognition device successively transmits several first signals which are timing tops, and the organ identification responds to each synchronization signal by issuing a second corresponding signal which is a response bit. More concretely, if the identification unit must for example provide the series of bits 1011 for identify himself to the recognition device, he will issue a impulse upon receipt of a first synchronization signal sent by the recognition device, do not send anything after receiving a second synchronization signal, send a pulse after reception of the third synchronization signal, and send a pulse after reception of the fourth synchronization top. So the recognition device can reconstruct the series of bits sent by the identification unit, and know the reaction time by evaluating the time between the program synchronization signal and reception of the pulse emitted by the device recognition, for the first, third and fourth response bits. In such an access system, the reception level of the transmitted pulses by the identification organ is conditioned by several parameters such as the position of the AOI antenna of the identification unit with respect to the ADR antenna of the recognition device, or by the electromagnetic disturbances introduced by the environment. So the level of reception of signals emitted by the identification unit is different for each data exchange, which more or less distorts the evaluation of the reaction time of the identification body.

En se référant à la figure 2 dans laquelle on a représenté graphiquement un second signal impulsionnel SS tel qu'il peut être reçu par le dispositif de reconnaissance, ainsi que la valeur seuil de référence VSR correspondant au seuil de détection d'une impulsion par le dispositif de reconnaissance, on peut voir que l'évaluation de l'instant de réception du second signal impulsionnel dépend du niveau de réception de ce signal. En effet, si le niveau de réception est haut, comme pour la forme IH, la valeur seuil VSR est atteinte à un instant t1, alors que pour la forme IB correspondant à un niveau de réception plus faible, la valeur seuil est atteinte à un instant t2, avec t2 > t1. Ainsi, l'évaluation d'un temps de réaction est d'autant plus fausse que le niveau de réception est faible.Referring to FIG. 2 in which a second impulse signal SS as it can be received by the recognition device has been represented graphically, as well as the reference threshold value VSR corresponding to the threshold for detection of a pulse by the recognition device, it can be seen that the evaluation of the instant of reception of the second impulse signal depends on the level of reception of this signal. Indeed, if the reception level is high, as for the IH form, the threshold value VSR is reached at an instant t 1 , while for the IB form corresponding to a lower reception level, the threshold value is reached at an instant t 2 , with t 2 > t 1 . Thus, the evaluation of a reaction time is all the more false the lower the reception level.

Dans cette figure 2 on a encore représenté le second signal impulsionnel reçu amplifié SSA. Ce signal amplifié SSA est le signal reçu à un niveau haut ou bas qui a été amplifié de manière à ce que son amplitude maximale corresponde à une amplitude maximale de référence AMR, ainsi, ce signal amplifié SSA correspond tout aussi bien à l'amplification du second signal SS qu'il ait été reçu à un niveau haut IH, ou à un niveau bas IB. Comme on peut le voir l'instant t0 auquel le second signal amplifié SSA atteint la valeur seuil de référence est alors indépendant du niveau de réception du second signal par le dispositif de reconnaissance.In this FIG. 2, the second pulse signal received, amplified SSA, has also been shown. This amplified signal SSA is the signal received at a high or low level which has been amplified so that its maximum amplitude corresponds to a maximum amplitude of AMR reference, thus, this amplified signal SSA corresponds just as well to the amplification of the second signal SS that it was received at a high level IH, or at a low level IB. As can be seen from time t 0 at which the second amplified signal SSA reaches the reference threshold value is then independent of the level of reception of the second signal by the recognition device.

Dans la figure 3, on a représenté sous la forme d'un organigramme un protocole d'identification, permettant de voir notamment de quelle manière le niveau d'amplification à appliquer par le dispositif de reconnaissance à une série de seconds signaux peut être choisi. En 10, le dispositif de reconnaissance DR monté dans le véhicule émet un code dit code question en direction de l'organe d'identification. Cette première émission correspondant au début du protocole pourra être par exemple déclenchée par l'appui du conducteur du véhicule sur un poussoir d'une portière. Ce code question est destiné à être traité par l'organe d'identification qui pourra être un identifiant situé dans une poche du conducteur, de manière à ce que l'organe d'identification émette dans la suite un code réponse en direction du dispositif de reconnaissance pour que ce dernier reconnaisse la signature de l'organe d'identification.In Figure 3, there is shown in the form of a flowchart a identification protocol, making it possible to see in particular how the amplification level to be applied by the recognition device to a series of second signals can be chosen. In 10, the device for DR recognition mounted in the vehicle emits a code called question code towards the identification body. This first broadcast corresponding to the start of the protocol could for example be triggered by the support of the vehicle driver on a button on a door. This question code is intended to be processed by the identification body which may be an identifier located in the driver's pocket, so that the identification body subsequently emits a response code towards the recognition device so that the latter recognizes the signature of the identification body.

En 20, l'organe d'identification émet un signal étalon qui pourra par exemple être une impulsion de longue durée de manière à ce que le dispositif de reconnaissance évalue en 30 le niveau de réception des signaux émis par l'organe d'identification et en déduise l'amplification à appliquer. Chaque récepteur (dans l'identifiant ou le véhicule) pourra apporter une correction. Deux types de corrections peuvent être implémentées en 40. La première consiste à mesurer le niveau et à tabuler un retard ou une avance fonction du niveau. Par exemple une tension analogique (qui reflète le niveau) peut être convertie en un octet pour obtenir une avance ou un retard tabulé dans le précontrôleur. La seconde consiste à corriger le niveau pour que le signal soit d'une amplitude constante avant le seuil (fig. 2). Cela implique une correction automatique de gain.In 20, the identification unit emits a standard signal which may by example be a long-lasting pulse so that the recognition device evaluates at 30 the level of reception of signals emitted by the identification unit and deduce the amplification therefrom apply. Each receiver (in the identifier or the vehicle) can make a correction. Two types of corrections can be implemented in 40. The first consists in measuring the level and tabulating a delay or an advance depending on the level. For example a tension analog (which reflects the level) can be converted into a byte to get a tabulated advance or delay in the precontroller. The second is to correct the level so that the signal is of constant amplitude before the threshold (fig. 2). This implies an automatic gain correction.

En 50, le dispositif de reconnaissance va émettre des premiers signaux qui sont des tops de synchronisation pour que l'organe d'identification émette en réponse des seconds signaux correspondants de manière à transmettre la suite de bits réponse au dispositif de reconnaissance. Ces seconds signaux pourront être une impulsion émise dès réception du top de synchronisation correspondant si le bit à transmettre vaut 1, et aucune impulsion si le bit à transmettre vaut 0. Au cours de cette transmission, le micro-contrôleur pourra enregistrer les instants où sont émis les tops de synchronisation et les instants où sont reçus les seconds signaux amplifiés SSA correspondants, en vue de calculer en 60 le temps de réaction de l'organe d'identification. Enfin, le temps de réaction évalué sera jugé satisfaisant s'il est inférieur à un temps de réaction de référence, et trop important s'il est supérieur à ce temps de réaction de référence.In 50, the recognition device will emit the first signals which are synchronization tops so that the identification organ emits corresponding second signals in response so as to transmit the response bit sequence to the recognition device. These second signals could be an impulse emitted upon reception of the top of corresponding synchronization if the bit to be transmitted is 1, and none pulse if the bit to be transmitted is 0. During this transmission, the microcontroller will be able to record the moments when the tops of synchronization and the times when the second amplified signals are received Corresponding SSA, in order to calculate in 60 the reaction time of the identification body. Finally, the evaluated reaction time will be judged satisfactory if it is less than a reference reaction time, and too much important if it is greater than this reference reaction time.

Comme on le voit, le procédé selon l'invention s'adapte à un protocole d'identification classique sans nécessiter des modifications importantes du protocole, et permet donc une amélioration de la précision d'évaluation du temps de réaction pour un coût de fabrication très faible.As can be seen, the method according to the invention adapts to a protocol standard identification without requiring significant modifications to the protocol, and therefore allows an improvement in the evaluation accuracy of the reaction time for a very low manufacturing cost.

Claims (3)

Un procédé de sécurisation d'une communication entre un dispositif de reconnaissance (DR) et un organe d'identification (OI) apte à communiquer avec le dispositif de reconnaissance de manière à ce que le dispositif de reconnaissance puisse authentifier l'organe d'identification pour commander le déverrouillage d'ouvrants d'un véhicule et/ou autoriser le démarrage d'un véhicule, dans lequel l'authentification est basée sur une évaluation par le dispositif de reconnaissance d'un temps de réaction correspondant au temps qui s'écoule entre l'émission par le dispositif de reconnaissance d'un premier signal en direction de l'organe d'identification et la réception par le dispositif de reconnaissance d'un second signal (SS) émis par l'organe d'identification en réponse au premier signal, caractérisé en ce que chaque second signal (SS) est amplifié par le dispositif de reconnaissance pour avoir une amplitude maximale correspondant à une amplitude maximale de référence (AMR) encore appelée correction automatique de gain, et en ce que l'évaluation du temps de réaction est basée sur la mesure d'un intervalle de temps s'écoulant entre l'instant d'émission d'un premier signal et l'instant auquel le second signal amplifié (SSA) correspondant atteint une valeur seuil de référence (VSR).A method of securing a communication between a recognition device (DR) and an identification organ (OI) capable of communicating with the recognition device so that the recognition device can authenticate the identification organ for controlling the unlocking of the doors of a vehicle and / or authorizing the starting of a vehicle, in which the authentication is based on an evaluation by the recognition device of a reaction time corresponding to the time which has elapsed between the emission by the recognition device of a first signal towards the identification unit and the reception by the recognition device of a second signal (SS) emitted by the identification unit in response to the first signal, characterized in that each second signal (SS) is amplified by the recognition device to have a maximum amplitude corresponding to a maximum reference amplitude ( AMR) also called automatic gain correction, and in that the evaluation of the reaction time is based on the measurement of a time interval elapsing between the instant of emission of a first signal and the instant at which the corresponding second amplified signal (SSA) reaches a reference threshold value (VSR). Le procédé de sécurisation selon la revendication 1, dans lequel dans un premier temps l'organe d'identification émet en direction du dispositif de reconnaissance un signal d'étalonnage (20) pour que le dispositif de reconnaissance ajuste l'amplification (40) en fonction d'un niveau de réception dudit signal d'étalonnage (30), et dans un second temps (50) le dispositif de reconnaissance émet en direction de l'organe d'identification plusieurs premiers signaux successifs auxquels l'organe d'identification répond par l'émission de seconds signaux correspondants (SS), chaque second signal étant émis dès réception du premier signal correspondant.The security method according to claim 1, wherein in firstly, the identification unit transmits in the direction of the recognizing a calibration signal (20) so that the device recognition adjusts the amplification (40) according to a level of reception of said calibration signal (30), and in a second step (50) the recognition device emits towards the identification body several successive first signals to which the identification body responds by sending corresponding second signals (SS), each second signal being transmitted upon receipt of the first corresponding signal. Un procédé de sécurisation d'une communication entre un dispositif de reconnaissance (DR) et un organe d'identification (OI) apte à communiquer avec le dispositif de reconnaissance de manière à ce que le dispositif de reconnaissance puisse authentifier l'organe d'identification pour commander le déverrouillage d'ouvrants d'un véhicule et/ou autoriser le démarrage d'un véhicule, dans lequel l'authentification est basée sur une évaluation par le dispositif de reconnaissance d'un temps de réaction correspondant au temps qui s'écoule entre l'émission par le dispositif de reconnaissance d'un premier signal en direction de l'organe d'identification et la réception par le dispositif de reconnaissance d'un second signal (SS) émis par l'organe d'identification en réponse au premier signal, caractérisé en ce que le niveau du signal est mesuré et une correction temporelle est tabulée par un micro-contrôleur.A method of securing a communication between a recognition device (DR) and an identification organ (OI) capable of communicating with the recognition device so that the recognition device can authenticate the identification organ for controlling the unlocking of the doors of a vehicle and / or authorizing the starting of a vehicle, in which the authentication is based on an evaluation by the recognition device of a reaction time corresponding to the time which has elapsed between the emission by the recognition device of a first signal towards the identification unit and the reception by the recognition device of a second signal (SS) emitted by the identification unit in response to the first signal, characterized in that the signal level is measured and a time correction is tabulated by a microcontroller.
EP01121540A 2000-09-08 2001-09-10 Process for securing the communication in a hands-free access system Withdrawn EP1186736A1 (en)

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FR0011458 2000-09-08
FR0011458A FR2814015B1 (en) 2000-09-08 2000-09-08 METHOD FOR SECURING A COMMUNICATION FOR A HANDS-FREE ACCESS SYSTEM

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19802526A1 (en) * 1998-01-26 1999-07-29 Bosch Gmbh Robert Device for control of access activation for road vehicles
US5983347A (en) * 1996-08-08 1999-11-09 Daimlerchrysler Ag Authentication device with electronic authentication communication
DE19941428A1 (en) * 1998-09-02 2000-06-15 Marquardt Gmbh Lock system, esp. for motor vehicle, uses encoded control signal to change controller state if signal from authorized key is positively evaluated and transition time is within given range

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5983347A (en) * 1996-08-08 1999-11-09 Daimlerchrysler Ag Authentication device with electronic authentication communication
DE19802526A1 (en) * 1998-01-26 1999-07-29 Bosch Gmbh Robert Device for control of access activation for road vehicles
DE19941428A1 (en) * 1998-09-02 2000-06-15 Marquardt Gmbh Lock system, esp. for motor vehicle, uses encoded control signal to change controller state if signal from authorized key is positively evaluated and transition time is within given range

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FR2814015A1 (en) 2002-03-15

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