Abstract: A device for triggering an airbag having a controller, a trigger, electric lines between the controlled device and the trigger and a coil for attenuating high-frequency interference currents connected to the electric lines which in turn induces interference current into the lines as a result of an external magnetic alternating field. The attenuation of the induced interference current results from an external magnetic alternating field of the coil and a compensating coil is connected in the electric lines and arranged in the surrounding area of the coil so that the amount of current induced in the compensating coil is equal to that of the interference current induced in the coil by the external field and because they are in anti-phase, the resultant current is zero from any interference.

Abstract: A vehicle security system has an access monitoring device which includes an access control part and/or an electronic immobilizing device which comprises an immobilizer control part, located on the vehicle. An authentication device can be carried by the user for actuation, subject to authentication, of the respective control part on the vehicle via an associated wireless actuation communication channel. Both an actuation communication channel which needs a key, and a wireless actuation communication channel which needs no key (and communicates based on proximity, without manual actuation) are provided for actuating a control part on the vehicle, optionally via one or the other actuation communication channel. The actuation communication channel which requires a key is given priority over the corresponding actuation communication channel which needs no key.

Abstract: An immobilizing device for a motor vehicle includes an immobilizer control unit on the vehicle, one or more authentication elements which can be carried by the user, and an actuation communication channel for immobilizer actuation communications which require authentication, between the authentication element and the immobilizer control unit. The immobilizer control unit allows driving operation and/or engine starting only if the driving authorization check is positive. According to the invention, an immobilizer operating element arranged on the vehicle can be operated without any manipulation of an authentication element, for user-requested initiation of the immobilizer actuation communication processes which require authentication. Alternatively or additionally, the brake pedal can be used as an operating element for activating engine starting, once it has been enabled by the immobilizer control unit.

Abstract: An electronic authentication device has an authentication key unit for user authentication with respect to the target unit, which key unit communicates electronically with the target unit during an authentication communication process. An electronic authentication communication process is activated automatically when the key unit approaches the target unit or when a triggering element provided on the target unit is actuated. For increased protection against unauthorized authentication attempts, indicating apparatus are provided on the key unit to display the fact that an electronic authentication communication process is taking place. Also switching apparatus can be provided for allowing or blocking an authentication communication process, and a communication duration monitor can also be provided on the target unit to monitor the duration of an authentication communication process and block authentication if this duration exceeds a predetermined maximum duration.

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.