Abstract: A system and method for operating a remote control having a portable remote control unit which can control at least one function unit. The remote control unit and the function unit are connected with one another by way of a bidirectional data communication link, by which data can be transmitted by means of a symmetrical coding method. The remote control unit sends a learn mode reporting signal in a secret coding information learn mode to the controllable function unit which, in the learn mode, in turn, sends back an acknowledgment signal. Upon receipt of the acknowledgment signal, the remote control unit generates new secret coding information by means of the coding algorithm, as a function of basis secret coding information and of the previous secret coding information, and sends the new secret coding information to the function unit.

Abstract: The invention provides an ignition key-vehicle communication device having at least one electronic key which can be inserted into a vehicle-end ignition lock. A wireless key-vehicle communication component arranged on the key actuates at least one vehicle-end functional unit by activating an activation element which is arranged at the key end. To protect against incorrect operation, means are provided for detecting when a key is inserted into the ignition lock and/or is inserted in a specific position in the ignition lock, and disabling communication between this key and the functional unit to be actuated in response thereto. The means for protecting against incorrect operation are arranged on the key.

Abstract: The invention provides a vehicle security device with an electronic use-authorization coding arrangement for preventing unauthorized access to the vehicle. The vehicle security device utilizes digital signature algorithm for encrypting and transmitting authorization and synchronization information, so that the storage of secret information is essential only at the key unit in order to transmit authorization and/or synchronizing information from the key unit to the vehicle unit in a way which is very effectively protected against falsification. Thus, reading out vehicle unit information does not permit unauthorized manufacture of a copied key.

Abstract: The invention provides a vehicle security device utilizing a rapid encryption method which operates on the basis of a "one-way function" and which requires storage in the vehicle of at most one item of secret coded information in a single piece of equipment, out of any desired number of pieces of equipment involved in vehicle security. In all such pieces of equipment only the one-way function values corresponding to inverse images stored in a key unit need to be present, the reading out of the said one-way function values making unauthorized manufacture of a copied key impossible. Security against interception and storage of information transmitted at the key end in order to produce copied keys is ensured by including an item of random information, transmitted at the vehicle end, in this authentication information.

Abstract: The invention provides a vehicle security device with an electronic use-authorization coding arrangement for identifying authorized access to the vehicle. The vehicle security device utilizes an encryption method which operates on the basis of a one-way function, so that it is only absolutely necessary to store secret code information at the key end, specifically in the form of different inverse images of a one-way function. Only the one-way function values corresponding to these inverse images need be present at the vehicle end, a reading-out of which does not permit unauthorized manufacture of a copied key because of the virtual irreversibility of the one-way function.

Abstract: In the new vehicle safety device according to the invention, random code information used to control the release of an electronic drive-away block arrangement consists of a combination of a plurality of partial information generated separately in operationally essential vehicle units which are separated from one another. The partial information is combined in a linking unit connected with these units for total random code information. Even after a code data exchange protocol has been intercepted by an unauthorized person, the latter, because of the structure of the safety device, can operate the vehicle only by replacing all of these units, which renders such unauthorized use by strangers unattractive because of the manipulations and expense required for this purpose.

Abstract: A frequency generator module has a first generator circuit and a second generator circuit, the frequencies of these circuits being variable by a physical parameter, especially a distance or angular value, with two coils arranged coaxially at a mutual spacing on linear or curved, tubular coil holders, the inductance of these coils being variable by a core displaceable in the coil holder. The combined generator module is connected by a control circuit to a changeover switch which alternately switches the output of one of the two coils to the input of the frequency generator module. A short-circuit ring is arranged in an axially normal plane between the two coils, for the duration of a specific number of pulses of the generator circuit formed from the coil and the generator module.