Method and device for protecting a reading device for card-shaped data carriers from unauthorized evaluation or copying of magnetically encoded data of an inserted card-shaped data carrier

Anti-tampering system for use with a reading device for the authorized detection of information magnetically stored on a card-shaped data carrier, which reading device comprises a first respective authorized magnetic field reading head for scanning a card-shaped data carrier and an evaluation and control circuit for evaluating the output signal of the authorized magnetic field reading head and for converting the information contained in the output signal into a digital data set, with a noise field generator which generates a magnetic noise field in order to apply noise to a second respective unauthorized magnetic field reading head which might have been fitted in the immediate vicinity of the reading device with fraudulent intent under certain circumstances,

• wherein the noise field generator comprises a signal-based model which is configured to copy the effect of the noise field on the output or sum signal of the authorized magnetic field reading head and this modeled copy is designed to compensate the effect of the noise field on the output or sum signal of the authorized magnetic field reading head and thus reconstruct a wanted signal dependent on an inserted card-shaped data carrier from the output or sum signal of the authorized magnetic field reading head;
• wherein the signal-based model is provided in the form of a digital model filter;
• and
• wherein the model filter is adapted during operation, continuously or at regular intervals, and is constantly adapted to a changing transmission behavior of the real route, and at least one set of stored filter parameters is compared at least on a recurring basis with a set of filter parameters of the adapted model filter, and the anti-tampering system is configured to emit a status or error message for a primary device controller in the event of qualified variances.

Method of securing a reading device for card-shaped data carriers to prevent unauthorized evaluation or copying of magnetically encoded data which is detected in the reading device for card-shaped data carriers, whereby a magnetic noise field is generated via a noise field coil disposed in the immediate vicinity of an insertion orifice for inserting card-shaped data carriers or in the region of a legitimate or authorized magnetic field reading head of the reading device in order to disrupt or affect with this noise field a magnetic field reading head which might have been fitted with a view to interception or with fraudulent intent under certain circumstances whilst the magnetic field of a card-shaped data carrier is being recorded,

• comprising
• operating or disposing at least one noise field coil so that the authorized magnetic field reading head is also affected by the noise field of the noise field coil as the magnetically encoded data of a card-shaped data carrier is being read,
• detecting an output or sum signal of the authorized magnetic field reading head generated from the wanted signal of a card-shaped data carrier and from the effects of the noise field,
• compensating or filtering out the effect of the noise field of the noise field coil in the output or sum signal of the authorized magnetic field reading head or selectively filtering the wanted signals out of the output or sum signal of the authorized magnetic field reading head,
• evaluating or further processing the wanted signal inside the reading device or in peripheral electronic units,
• reproducing an effect of a noise control signal or the noise field generated by the noise control signal on the output or sum signal of the authorized magnetic field reading head,
• wherein an additional noise control signal is at least periodically superimposed on the noise control signal which, in terms of essential properties, is similar to a signal that is obtained as a wanted signal when the magnetic stripe of a card-shaped data carrier is read by the magnetic field reading head.

Anti-tampering system for use with a reading device for the authorized detection of information magnetically stored on a card-shaped data carrier, which reading device comprises a first respective authorized magnetic field reading head for scanning a card-shaped data carrier and an evaluation and control circuit for evaluating the output signal of the authorized magnetic field reading head and for converting the information contained in the output signal into a digital data set, with a noise field generator which generates a magnetic noise field in order to apply noise to a second respective unauthorized magnetic field reading head which might have been fitted in the immediate vicinity of the reading device with fraudulent intent under certain circumstances,

• wherein the noise field generator comprises a signal-based model which is configured to copy the effect of the noise field on the output or sum signal of the authorized magnetic field reading head and this modeled copy is designed to compensate the effect of the noise field on the output or sum signal of the authorized magnetic field reading head and thus reconstruct a wanted signal dependent on an inserted card-shaped data carrier from the output or sum signal of the authorized magnetic field reading head, and
• wherein at least one other noise field coil is provided and the noise field coils are disposed in a different spatial arrangement or different orientation or have a different magnetic field geometry and in particular are mounted in the vicinity of an insertion orifice for the card-shaped data carrier, and are supplied with stochastic noise control signals that are not correlated with one another.