EP0212046B1 - System for locking and/or unlocking a security device - Google Patents

Description

The invention relates to a method for locking and / or unlocking a remote-controlled locking device, in particular for motor vehicles, with a transmitting device and a receiving device, each a data storage and comparator at the time of sending and receiving, the receiving device also comprising a switchable signal generator and a transmitter and the Transmitting device also has a receiver and wherein coded information is exchanged, compared and, if they match, a control signal is generated for the locking device.

Methods in which coded information is transmitted by a transmitter for actuating safety devices are known in particular as door locking of motor vehicle doors and already have a high level of security against unauthorized opening of the motor vehicle doors.

However, it is possible to record the coded information with a receiving device during an opening process and to open the parked and locked motor vehicle easily and without damage by later sending this information.

For a method of the type mentioned at the outset, a control device for locking and / or unlocking a security device has therefore already been proposed, in which the receiver has a signal generator for generating further coded information and the further coded information can be stored in the memory of the receiver device and by one Transmitter of the receiver device can be emitted, and that the transmitter device has a receiver for receiving the further coded information and the further coded information can be stored in the memory of the transmitter device. (EP-A-84 116 366.0)

However, this does not provide sufficient security against the interception of coded information and its unauthorized use, because when listening to the wirelessly transmitted signals it is hardly more trouble to decode a simple transcoding if one already knows the code as such.

There is therefore the task of significantly improving security against unauthorized unlocking of the security device in a method of the type mentioned at the outset.

This object is achieved in that when the transmitter device is actuated, the signal generator is switched on and a plurality of further coded information items are generated which, after deletion of the previously stored coded information, are stored in the data memories of the transmitter and receiver device in order to be activated the next time the closing device is actuated Avoid code repetition.

The additional security gained with the invention is that, firstly, a large number of codings are provided and that the selection of the coding used from this large number is incomprehensible to an unauthorized person. Compared to the known control device, not only a simple increase in the coding possibilities is provided, but also a transcoding sequence in which it is impossible to infer from a intercepted and decrypted coding to the "valid" coding on the next actuation.

Advantageous refinements of the inventive concept are described in subclaims 2 to 13.

The generation and transmission as well as the storage of the further coded information can preferably be switched on by a switch of the receiver device. If the switch is the ignition switch (terminal 15) of the motor vehicle, a completely new coding takes place automatically with each starting process or at a later point in time, which coding is stored both in the receiver and in the transmission device. Several completely independent random numbers can serve as code. However, in addition to one or more random numbers, an algorithm can also be generated, which is also stored with the random number or numbers in the receiver and in the transmitting device. This increases the number of codes which can be used until the next recoding, without having an excessively large memory in the transmitting device for storing a correspondingly large number of Random numbers is required.

The algorithm and the number of its applications can be chosen such that it is impossible to calculate the coding to be used next with the previously recorded coded information before applying a new random number. In particular, even if several random numbers are stored, the determination of the algorithm is made more difficult by the fact that, in the event of an unauthorized recording of the coded information transmitted by the transmitting device, it does not appear whether two coded information items recorded in succession either two by the one-time application of the algorithm Coded information that is different from one another is whether there is two pieces of information that differ due to repeated application of the algorithm (this would be the case if one or more coded information were not recorded) or whether one of the coded information recorded represents a new random number.

The storage of a corresponding number of random numbers and / or the derivation of further codes with the aid of an algorithm enables the unlocking and locking process to be carried out many times without the need to generate a new code in the receiver device, that is to say: the code used is changed from one unlocking or locking process to the next even if no recoding takes place. It is thus possible to open and close a motor vehicle several times using a different code, without the ignition switch in between to operate. This is necessary, for example, at campsites if the holiday maker rarely uses his vehicle to drive, but opens and closes the doors several times a day.

In a practically implemented system, ten random numbers are generated during a recoding process and the possibility is provided to vary each of the ten random numbers nine times with the aid of an algorithm. Hundreds of different codes can thus be used in succession, unless recoding is carried out beforehand by actuating the ignition switch.

According to a development of the invention, the algorithm can be designed to be variable in that it is dependent on the applicable random number. This makes it possible, for example, to use a first algorithm for varying the first random number stored after recoding and a second algorithm after the second random number, etc.

The transmission of the random number generated for the recoding and the algorithm must be protected against unauthorized recording. According to a development of the invention, the transmission takes place when the ignition key, which is physically combined with the transmission device, is in the ignition lock. The transmission can then take place over a very short distance in the closed motor vehicle, so that an unauthorized reception of the coded information from the outside becomes practically impossible.

According to an improvement of this development, the random numbers and the algorithm can be transmitted at a point in time which is also determined from random numbers and is therefore not known to third parties. Because a relatively large number of codes are stored after transcoding, the system according to the invention maintains its safe function even if a transcoding which is provided and initiated per se ultimately does not take place, for example because the driver of a vehicle switches the motor vehicle off again before the above-mentioned point in time for transmission of the recoding determined from random numbers has been reached.

In the system according to the invention, it should only be noted that the same codes are present in the two memories. For this purpose, it is only necessary to transmit the new codes if it has been determined by appropriate acknowledgment signals between the transmitting device and the receiving device that a flawless transmission is guaranteed.

Fig. 1

ein vereinfachtes Schaltbild einer Sendevorrichtung,

Fig. 2

ein vereinfachtes Schaltbild einer Empfängervorrichtung,

Fig. 3

Flußdiagramme von Programmen für die in der Sendevorrichtung und in der Empfängervorrichtung enthaltenen Mikrocomputer,

Fig. 4

ein Flußdiagramm eines Programms zur Weiterschaltung der Codierung nach einem Ent- bzw. Verriegelungsvorganges und

Fig. 5

eine schematische Darstellung der Übertragungsstrecke für die Umcodierung.

An embodiment of the invention is shown in the drawing using several figures and described in more detail below. It shows:

Fig. 1

a simplified circuit diagram of a transmission device,

Fig. 2

a simplified circuit diagram of a receiver device,

Fig. 3

Flow diagrams of programs for the microcomputers contained in the transmitting device and in the receiving device,

Fig. 4

a flowchart of a program for advancing the coding after an unlocking or locking process and

Fig. 5

a schematic representation of the transmission path for the recoding.

Identical parts are provided with the same reference symbols in the figures.

1 comprises a microcomputer 3, which is preferably designed as a one-chip computer and to which a quartz crystal 4 is assigned for clock generation. A battery 7 is used for the power supply, which is designed as a button cell to achieve a small size of the device according to FIG. 1. A push button switch 6 is used to switch on the transmission device. An output 8 of the microcomputer 3 leads via an amplifier 9 to a light-emitting diode 10. A receiver 11 formed by a phototransistor is connected via a further amplifier 12 to a coding input 13 of the microcomputer 3. Furthermore, the receiver 11 is also connected to an activation input 14 of the microcomputer 3. This activation input 14 can also be controlled by the switch 6 via a diode 15.

The function of the transmission device 1 and of the receiver device according to FIG. 2 described in the following paragraph will be explained in more detail later in connection with FIGS. 3 and 4.

The receiver device 2 also has a microcomputer 16 with a quartz crystal 17. The microcomputer 16 is connected to the power source of the motor vehicle (terminal 30) via the connection 18. The connection 19 is connected to the ignition switch (terminal 15) of the motor vehicle, so that the microcomputer 16 is actuated each time the vehicle is started.

The inputs 20 of the microcomputer 16 are each assigned to a locking device arranged in a door of the motor vehicle and can be used to actuate the microcomputer 16 by mechanical actuation by means of a key if the normal function of the control device is disturbed.

A generator 22 generating a random pulse sequence is connected to a further input 21 of the microcomputer 16. A transmitter 24 formed by a light-emitting diode is connected to an output of the microcomputer 16 via an amplifier 23. Furthermore, in the case of an amplifier 25, a further transmitter 26 formed by a further light-emitting diode is connected to an output of the microcomputer 16.

Receiving means 27 formed by a phototransistor are connected to an input of the microcomputer 16 via an amplifier 28. Each of the three inputs 29 of the microcomputer 16 leads to a locking device for the central locking of the motor vehicle and transmits the control signal emitted by the microcomputer 16.

The program stored in the microcomputer 3 of the transmitting device is started at 31 (FIG. 3) when the microcomputer 3 receives a corresponding command by actuating the key switch 6. Coded information is then sent out at 33 (with the aid of the light-emitting diode 10 in FIG. 1). After receiving the coded information in the receiver device 2 with the help of the phototransistor 27 and the amplifier 28 (Fig. 2). At 34, the program continues in the receiver device. As long as no information is received, this program goes into a waiting loop via the program part 36.

At 35, it is derived from the received coded information which transmission device (key) has transmitted the information. For this purpose, additional information is added to the coded information. The same program flow is provided for each of the keys to be used, but with different variables. Otherwise, all keys would have to be re-encoded when switching from one code to another or when re-encoding, which is impossible due to the different storage locations of the keys.

After determining in the example shown in Fig. 3 that it is the master key (HS), a decision is made at 37 as to whether the encoded information transmitted is a command encoded with the code which is next to be actuated the locking devices is provided (current code). If this is not the case, a decision is made at 38 as to whether it is the code last used. If this is not the case, then the system according to the invention assumes that an unauthorized code has been used and goes back to readiness via the program part 36, which essentially delays in order to make systematic testing more difficult.

If, however, it was found at 38 that the code last used was sent out by the transmitting device, an acknowledgment signal B is transmitted to the transmitting device at 39 via the light-emitting diode 24 (FIG. 2), which signal is received by the phototransistor 11 (FIG. 1).

In the meantime, the program of the transmitting device, from sending the coded information at 33 via a delay at 40, which determines the duration of the readiness to receive, to a branch 41, at which it is decided, depending on the receipt of an acknowledgment signal, whether a repetition at 42 of the transmitted coded information or at 43 the code is advanced. If no receipt has been received by the sending device, the transmitted code is repeated four times, which is registered in a branch 45. However, if a receipt has been received, then the code is advanced at 43, which is explained in more detail in connection with FIG. 4. In the case of a further branch 44, the program is led to the program part 42 when an acknowledgment signal B has been sent out by the receiver device, which indicates the receipt of the previous code. If, however, which is described in more detail below, the receiver device acknowledges unlocking or locking the doors by sending an acknowledgment signal A, then the branch 44 forwards the program to branch 46, which depends on whether the doors are locked or not. or unlocked. A correspondingly different acoustic signal is triggered at 47 and 48, whereupon the program leads to the end 51 via the point 49 and via a program part 50 which switches off the microcomputer 3.

If it has been determined at 37 that the current code has been transmitted, it is checked at 52 whether the central locking system is unlocked or locked. If the doors are locked (closed), the program is continued at 54 with the transmission of an acknowledgment signal A to the transmitting device and a command is given at 56 to the central locking system for unlocking. If the doors are unlocked when the coded information arrives, an acknowledgment signal A is sent to the transmitting device at 53 and a command to lock is given at 55. The code is then switched on at 57, whereupon the program remains in the waiting loop 34, 36 until a next signal is received. 4 is a more detailed representation of the program parts 43 and 57 of the flow chart of FIG. 3. It is assumed that with a recoding N random numbers (Z₁ to Z _N ) and an algorithm A and generated in the transmitter and in the receiver device can be stored. Furthermore, the algorithm A is applied K times. The coding is then based on the following numbers Z _{i, k} :
Z _1.0 , Z _1.1 , Z _1.2 to Z _{1, K} ,
Z _2.0 , Z _2.1 , Z _2.2 to Z _{2, K} to
Z _{N, 0} , Z _{N, 1} , Z _{N, 2} to Z _{N, K.}

When program part 43 or 57 is reached, it is first determined whether the next code is to be carried out by using algorithm A or by reading out the next random number Z _n from the memory. If k is less than K, the algorithm has not yet been used as often as intended, so that the algorithm is applied at 62 and the index k is subsequently increased by 1 at 63. If, however, k is K, a new random number Z _{n, 0 is} read from the memory with the aid of the program part 64, the index n is increased by 1 at 65 and the index k is set to 0 at 66. The program parts 67 to 71 are addressed when the transmitter device transcodes, in which new random numbers Z 1 to Z _N and a new algorithm are determined and transferred to the memory of the transmitter and receiver device. The determined random numbers and the algorithm are stored at 68. At 69, the running random number (code) present in the program as a variable is set equal to the first random number, and at 70 and 71 the indices k and n are set to their initial values brought.

Compared to the change in the random numbers described in connection with FIGS. 3 and 4 by means of an algorithm which remains constant until the next recoding, a further security against an unauthorized determination of the code can be achieved in that the algorithm can be changed. In the case of recoding, for example, several algorithms can be stored which are used in a predetermined order. However, the application of the algorithms can also be made dependent on the respective random number. For example, a first algorithm can be applied when a particular bit of the random number is 0, and a second algorithm when this bit is 1.

5 shows a schematic illustration of an exemplary embodiment of a transmitting device 1, which is accommodated in the grip part 80 of an ignition key 81. After the key 81 has been inserted into the ignition lock 82, the ignition can be switched on in a manner known per se and the engine of the motor vehicle can be started. This generates random numbers and an algorithm in the receiver device (FIG. 2), which are emitted via the light-emitting diode 26 and received by a phototransistor 11 in the transmitter device.

The transmission of the further coded information according to the invention can be made even more "bug-proof", for example, by sending it after a random period of time after actuation of the ignition lock. The invention is also not limited to the fact that the transmission of the further coded information is triggered by the actuation of the ignition lock. For example, exceeding a specified speed can trigger the transmission. In addition, a system according to the invention can be designed such that the transmission by the user can be triggered deliberately - for example by pressing a key on the key. In this embodiment, the second transmitter of the receiver device can possibly be omitted and the first transmitter, for example attached to the vehicle side, can carry out the transmission. The user can then occasionally re-encode if he is safe from unauthorized recording.

Claims (13)

1. Method for locking and unlocking a remotely operated closing device, in particular for motor vehicles, having a transmitting device (1) and a receiving device (2), in each case one data memory and data comparator on the transmitter and receiver side respectively, the receiving device (2) having in addition a signal generator, which can be switched on, and a transmitter and the transmitting device (1) having in addition a receiver, and coded information being exchanged, compared and, in the event of coincidence, a drive signal being generated for the closing device, characterised in that, upon actuation of the transmitting device (1) the signal generator is switched on and a plurality of further coded items of information are generated which, after deletion of the previously stored coded information in the data memories of the transmitting and receiving device (1,2) are stored in order to avoid a repetition of coding at the next actuation of the closing device.
2. Method according to Claim 1, characterised in that the further coded information is formed from random numbers.
3. Method according to Claim 1, characterised in that the further coded information is formed from one or more random numbers and an algorithm for modifying the random number or random numbers.
4. Method according to Claim 1, characterised in that the algorithm is used for the repeated modification of a random number.
5. Method according to Claim 1, characterised in that the algorithm is changed from random number to random number.
6. Method according to Claim 1, characterised in that for the purpose of locking the closing device, the transmitting device (1) transmits the same coded item of information which was previously transmitted for the purpose of unlocking.
7. Method according to Claim 1, characterised in that for the purpose of unlocking the closing device the transmitting device (1) derives and transmits a coded item of information from the stored further coded information and stores it in the transmitting device (1) until the next derivation.
8. Method according to Claim 7, characterised in that the derivation of the coded information to be transmitted does not occur until an acknowledgement signal transmitted by the receiving device (2) is received by the transmitting device (1).
9. Method according to Claim 1, characterised in that the receiving device has two transmitters (24, 26), of which a first (24) is provided for acknowledging the coded item of information received by the transmitting device (1) and a second transmitter (26) is provided for transmitting the further coded information.
10. Method according to Claim 9, characterised in that the second transmitter (26) transmits the further coded information in such a way that unauthorised picking up is prevented.
11. Method according to Claim 3, characterised in that the number of codes which are derived in each case from a random number by (multiple) use of an algorithm is selected to be one smaller than the number of derived codes necessary for calculating the algorithm, and in that after this a different random number is used.
12. Application of the method according to Claim 10 to the closing device of a motor vehicle having ignition lock, characterised in that the second transmitter (26) is arranged in the direct vicinity of the ignition lock (82), and in that the further coded information is generated after the actuation of the ignition lock (82) and then transmitted.
13. Application according to Claim 12, characterised in that the further coded information is transmitted after a random time period after the actuation of the ignition lock (82).

Images