AU730422B2 - Method for allocating a remote control to a base station - Google Patents

Description

-1- Method for allocating a remote control to a base station Prior Art The invention relates to a method for allocating a remote control to a base station as described in the patent application File No.: 196 45 769.6.

According to it, the allocation of a remote control to a base station arranged in a vehicle takes place, the base station emitting a search signal whereupon remote controls within the range of the search signal respond by returning a challenge signal at the characteristic points in time for the remote controls.

The base station ascertains the remote controls present by evaluating the input times of the challenge signal responses. One of them selects it and carries it out with a "challenge-response" verification. Because a clear remote control recognition is already possible through the exchange of only one signal :and the signal, because it is not security relevant, can be constructed simply, g 15 the complete recognition takes place very quickly. Decisive for the speed of S• allocation is above all, then, the following challenge-response verification. It is based on the carrying out of security relevant calculation operations which are extensive and require appropriate time. User-specific integrated switching circuits (ASIC) developed specifically for the purpose are used for the quick 20 recognition of the challenge and response signal, and carry out the challenge and response calculation within less than three milliseconds. By this means, the triggering of the allocation test can take place by means of the activating of the door handle of a vehicle, so that the opening of the door is only possible when the remote control is verified as belonging to the vehicle. The user is not aware of the allocation process. The ASICS previously mentioned fulfil their function well but are comparatively expensive to manufacture.

The object of this invention is to provide a method for the allocating of a remote control to a base station which permits a rapid implementation of an allocation test, in particular a rapid carrying out of verification communication.

According to the present invention there is provided a method for allocating a _A re,,---remote control to a base station in which the base station emits a search 20/12/00,tdl 1208.spe, 1 -2signal, the remote control returns a challenge signal upon agreement of the search signal with a stored reference signal and the base station then emits at each allocation a changeable activation signal for the verification of the matching with the remote control, wherein the changeable activation signal is determined before the emission of the search signal by the base station and is called up only for the allocation.

The method of the invention can be realised easily as a program in the microprocessor in the base station or remote control and renders the providing of an ASIC superfluous. It guarantees the same security as with the use of an ASIC. A gaining of security can be realised by the speed of the challengeresponse calculation being controlled specifically whenever the challengeresponse dialogue is carried out several times in succession.

S: 15 An embodiment of the invention will be described in greater detail in the following with the aid of the drawing.

Drawing Figure 1 shows a block diagram of an allocation device, Figure 2 a flow chart 20 illustrating its operation.

o*oo *o S• Description Figure 1 shows a base station 10 which can be part of a device or object or can be permanently allocated to one. The base station can, for example, be part of the access control device of a building or a vehicle. A further component of the access device shown in Figure 1 is a remote control called an activating device 20 in the following which is allocated to the base station functionally via a signal transmission path 30 without challenge. The remote control can, in particular, be a transponder. The base station 10 acts on the technical device to a part of which or to which it is allocated via 20/12/00,tdl 1208.spe,2 0, W099/16989 PCT/DE98/02808 3 active connections. When used in a motor vehicle, it controls, for example, the access to the vehicle or its operation.

A component of the base station 10 is a microprocessor 13 which controls the operation of the base station 10, additionally causing, in particular, the output of signals and the evaluation of incoming signals. A transmitter receiver 11 for the challengeless transmission reception of signals is connected to the microprocessor via the signal transmission path 30. Further, a memory 14 is allocated to the microprocessor 13. In it is allocation information on the basis of which the base station 10 recognises allocated remote controls 20. The allocation information is: a serial number 15, a manufacturer's code 17, a cryptic key code 31, a directory 16 with information about the remote controls allocated to the base station 10 and a random number 18. The serial number 15 is characteristic for base stations 10 and remote controls 20 allocated to one another. It is established by the manufacturer of the technical device to which the base station 10 and the remote control 20 are allocated. In the case of use in motor vehicles, the establishing of the random number can be made by the manufacturer of the motor vehicle. The manufacturer's code 17 indicates the device belonging to it, ie. the base station clearly. It is provided by the manufacturer and cannot be changed. The directory 16 contains a data set 16a, 16b, 16c for each allocated remote control which contains the group number 25 of a remote control 20, its manufacturer's code 27, a random number and a desired response. The group numbers 25 distinguish between the remote controls with the same serial number allocated to the one base station 10, the respective manufacturer's code 27 serves, together with the cryptic key code 31 and the random number 18 which is generated by the microprocessor 13, the forming of the desired response. The cryptic key code 31 is, preferably, also established by the manufacturer of the technical device to which it belongs, for example a motor vehicle manufacturer. A data set 16a, 16b, 16c respectively allows the verification of a remote control belonging to it.

The remote control has a transmitter receiver 21 corresponding to the transmitter receiver 11 of the base station for the reception of signals emitted by the base station W099/16989 PCT/DE98/02808 4 or for the transmission of signals to the base station 10. Analogous to the base station, a microprocessor is connected upstream of the transmitter receiver 21 which controls the operation of the remote control 20, particularly undertaking the evaluation of the signals input through the transmitter receiver 22, introducing measures dependent on the results and overseeing the emission of output signals. A storage unit 24 is allocated to the microprocessor 23 in which allocation information for the allocating of the remote control 20 to a base station 10 is stored. The serial number 15, the group number 25, a manufacturer's code 27 and a cryptic key code 31 are also stored analogous to the base station 10. The significance of the contents of the memory corresponds to the same kind of memory contents in the memory 14 of the base station 10. The manufacturer's code is provided by the manufacturer of the remote control 20 and indicates it clearly. The serial number 15 is a characteristic code for the entire device consisting of the base station and the remote controls 20 belonging to it and is identical to the serial number contained in the memory 14 of the base station 10. The group number 25 distinguishes the remote controls 15 having the same serial number 15 from one another. It is established by the user during the operation of the entire device. The cryptic code 31 is established by the manufacturer of the technical device belonging to the base station 10 and is identical with the one in the base station. It serves, in connection with the manufacturer's code 27 and the challenge signal directed from the base station 10 over the signal transmission path to verify whether it belongs to a base station 10. Between the base station 10 and remote controls 20 is a signal transmission path for the transmission of challengeless, transmissible signals between the transmitter receiver 21 on the side of the remote control and the transmitter receiver 11 on the side of the base station. Signals output from the transmitter receiver 11 on the side of the base station reach all remote controls within its range. Infrared or high frequency signals are used.

Several remote controls can be allocated to one base station 10. All remote controls and the base station 10 have an identical serial number in their memories 14, 24 and use, in the verification, a cryptic key code 31. The individual remote controls 20 differ by dint of their group numbers 25 and their manufacturer's codes 27.

W099/16989 PCT/DE98/02808 The operation of the device shown in Figure 1 will, in the following, be described with the aid of Figure 2. A letter B or F is placed in front of the sequential steps, indicating whether the respective sequential step takes place in the base station 10:B or in the remote control 20:F. The triggering mechanism can exist in the activating of the door handle in the case of use in a motor car.

On the basis of a signal emitted at the trigger, the microprocessor 13 of the base station sets the internal counter A to the value 0, step 102. It then takes the random number 18 which builds the activating signal, in the following called the challenge signal, from the memory 14 and the responding signal 16a, 16b, 16c, in the following called the desired response signal for all of the remote controls 20 allocated to the base station 10, Step 104.

It then increases the counter A by 1, step 106. The microprocessor 13 then introduces the emitting of a search signal through the transmitter receiver 11, step 108. The search signal comprises, alongside start and synchronisation information, in particular the serial number 15 stored in the memory 14. It is preferably unencoded and will be received by all the remote controls 20 within the range of the signal transmission path via its transmitter receiver 21.

At the time of input, its microprocessors 23 test whether the serial number 15 transmitted with the input of a search signal agrees with serial number stored in the memory 24 of the remote control and serving as reference signal. In the case of non-agreement, the remote control 20 does not participate any longer in the matching test. In the case of agreement of the compared signals, the microprocessor 23 occasions an answer in the form of a challenge signal, step 112. A short, simply constructed signal serves as challenge signal, for example the group number 25 of the respective remote control in bit-coded form. The challenge signal is, like the search signal, preferably unencoded. The microprocessor 24 brings about the emission of the challenge signal after the course of a characteristic period of time determined by the group number 25 for the remote control 20 from the input of the search signal. It then takes place in a time window of predetermined length.

The emission is measured in such as way that a definite allocation of the challenge signal to the time window is possible both for the remote control 20 and for the base station W099/16989 PCT/DE98/02808 6 By means of examining in which time windows challenge signals have entered, the microprocessor 13 establishes which remote controls are present with which group numbers, step 114. If no present remote control 20 is determined, the microprocessor 13 tests the value of the counter A, step 116. If it is smaller than a given reference value, for example 5, it causes the immediate re-emission of a search signal immediately and repeats the procedure from Step 118 onwards. If the reference value is exceeded, the microprocessor 13 breaks off the matching test, Step 117. If the test in Step 114 revealed that at least one remote control 20 is present, the microprocessor 13 selects one of the present remote controls 20 with which it then carries out a matching test, Step 118.

Following the selection of a remote control, it counts a second internal counter B one step up, Step 120. The microprocessor 13 then prompts the emission of a subsequent challenge signal over the transmitter receiver 11. The random number 18 stored in the memory 14 serves as a challenge signal.

The selected remote control 20 receives, over its transmitter receiver 21 the challenge signal and creates from it, through attachment with the manufacturer's code 27 and the cryptic key code 31, a response signal, which it returns as an answer to the base station Step 124.

Its microprocessor 13 compares, after reception, the response signal returned by the remote control 20 with the desired response signals 16a, 16, 16c previously loaded in Step 104 of the selected remote control 20, Step 126. If the desired response signal and the response signal agree, the microprocessor 13 sets the internal counter B back to the value 0, Step 132 and prompts the emission of an enable signal enabling, for example, access to a vehicle and/or its operation, Step 134. Finally the microprocessor 13 determines a random number 18 and ascertains for each group number entered in the directory 16 a new desired response signal, Step 136. With the random number 18 and the newly formed desired response signals, it occupies the memory 16a, 16b, 16c and 18 again. The new contents of the memory serve as basis for the allocation test in the W099/16989 PCT/DE98/02808 7 connection to the next repeated tripping process. With the new writing of the memory contents 16 and 18, the matching test procedure is concluded, Step 138.

If the test in Step 130 reveals that the limit allocated counter B is not yet exceeded, the microprocessor 13 also carries out a new determining of the random number 18 and the desired response signal 16a, 16b, 16c in accordance with Step 136. Then it continues with the repetition of Step 104 and loads the re-determined memory contents 18 and 16a, 16b, 16c again in order to then carry out Step 106.

A specific determining of a new random number and a new desired response signal can be carried out slowly in accordance with Step 136. As the new determining with authorised use does not take place until matching and the output of an enable signal takes place, a slow carrying out of Step 136 for the authorised user does not have an effect.

However, a false matching of a remote control to a base station is made difficult for an unauthorised person, even if he were to succeed in reproducing a challenge signal for the emission of a challenge signal to the remote control. By means of a purposive extending of the time to the carrying out of Step 136, it is also made difficult to establish a correct response signal through the permutative repetition of possible response signals.

Claims (7)

1. A method for allocating a remote control to a base station in which the base station emits a search signal, the remote control returns a challenge signal upon agreement of the search signal with a stored reference signal and the base station then emits at each allocation a changeable activation signal for the verification of the matching with the remote control, wherein the changeable activation signal is determined before the emission of the search signal by the base station and is called up only for the allocation.

2. The method as in Claim 1, wherein also the response signal is established by the base station before the transmitting of the search signal the response signal is determined, with which the remote control belonging to it is i to answer following reception of the changeable activation signal. o The method as in Claim 1, wherein the determining of the changeable activation signal takes place after completion of a successful allocation of a remote control with a base station. 20 4. The method as in to Claim 1, wherein a new, changeable signal is established when a response signal sent back by a remote control on an activation signal does not agree with the predetermined desired response signal in the base station.

5. The method as in Claim 1, wherein the search signal is emitted several times consecutively when a contact signal is not input following the preceding search signal.

6. The method as in Claim 4, wherein the implementation time for the new establishment of the changeable activating signal is extended with respect to the shortest possible implementation time. 20/12/00,tdl 1208.spe,8 -9-

7. A base station including a transmitter receiver which is designed for the emission of search and activation signals and for the reception of challenge and response signals of remote controls, means for the occasioning evaluation of the signals to be transmitted received via the transmitter receiver, a non-volatile memory unit for the storage of fixed and changeable allocation information which allocates at least one remote control to the base station and permits the matching test, characterised in that the means establishes the changeable activation signal before the transmission of the search signal from the base station and calls it up only for the allocation.

8. The base station as in Claim 7, wherein the non-volatile memory i unit is designed as an exactly one-time programmable memory medium.

9. A system including a base station as claimed in any one of Claims 7 or 8 and a remote control which is a transmitter receiver designed for the reception of search and activation signals and for the transmission of challenge and response signals, 20 comprises means for the evaluation occasioning of signals to be received transmitted, and a non-volatile memory for the storage of allocation ooo: information which allocate the remote control to a base station. .ooooi Dated this 20 h day of December, 2000. ROBERT BOSCH GMBH By their Patent Attorneys: CALLINAN LAWRIE 20/12/00,td 1208.spe,9