Method of detecting a redirection or relaying of a contactless data transmission using at least two sequentially driven transmitting antennas
First Claim
1. A method of detecting a relaying of a contactless electromagnetic data transmission, comprising the steps:
- a) transmitting a first electromagnetic field from a first transmitting antenna of a first unit having at least a transmitting capability;
b) sequentially after said step a), transmitting a second electromagnetic field from a second transmitting antenna of said first unit, wherein said first and second transmitting antennas are spatially separated from each other;
c) sequentially receiving said first electromagnetic field and said second electromagnetic field with a second unit having at least a receiving capability;
d) determining a first actual field strength value of a field strength of said first electromagnetic field and a second actual field strength value of a field strength of said second electromagnetic field as respectively received by said second unit;
e) comparing said first and second actual field strength values respectively with prescribed first and second nominal field strength values of a nominal value field; and
f) detecting that a relaying of at least one of said first and second electromagnetic fields has occurred if said comparing determines that said first and second actual field strength values unacceptably deviate from said prescribed first and second nominal field strength values of said nominal value field.
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Abstract
A method detects relaying of a contactless data communication by a radio amplifier for intercepting and manipulating the communication to achieve an unauthorized authentication. The method involves transmitting an electromagnetic field successively from at least two spatially separated antennas of a transmitting unit, receiving the transmitted fields in a receiving unit, determining field strength vectors of the received fields allocated to each antenna, and comparing actual values of the vectors with prescribed nominal values stored in a nominal value field that maps the true field strength distribution in multi-dimensional space around the transmitting unit. The actual field strength magnitude and the reception angle between the transmitting antennas can be determined from the vectors and compared with stored nominal values in this manner. When the determined actual values match prescribed nominal values of the nominal value field, the occurrence of a relaying of the signal can be reliably excluded.
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Citations
24 Claims
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1. A method of detecting a relaying of a contactless electromagnetic data transmission, comprising the steps:
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a) transmitting a first electromagnetic field from a first transmitting antenna of a first unit having at least a transmitting capability;
b) sequentially after said step a), transmitting a second electromagnetic field from a second transmitting antenna of said first unit, wherein said first and second transmitting antennas are spatially separated from each other;
c) sequentially receiving said first electromagnetic field and said second electromagnetic field with a second unit having at least a receiving capability;
d) determining a first actual field strength value of a field strength of said first electromagnetic field and a second actual field strength value of a field strength of said second electromagnetic field as respectively received by said second unit;
e) comparing said first and second actual field strength values respectively with prescribed first and second nominal field strength values of a nominal value field; and
f) detecting that a relaying of at least one of said first and second electromagnetic fields has occurred if said comparing determines that said first and second actual field strength values unacceptably deviate from said prescribed first and second nominal field strength values of said nominal value field. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification