Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L9/00—Cryptographic mechanisms or cryptographic arrangements for secret or secure communications; Network security protocols
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
  • G07C9/00—Individual registration on entry or exit
  • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
  • G07C9/00182—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with unidirectional data transmission between data carrier and locks
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
  • G07C9/00—Individual registration on entry or exit
  • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
  • G07C9/00309—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks
• • G—PHYSICS
  • G08—SIGNALLING
  • G08G—TRAFFIC CONTROL SYSTEMS
  • G08G1/00—Traffic control systems for road vehicles
  • G08G1/01—Detecting movement of traffic to be counted or controlled
  • G08G1/017—Detecting movement of traffic to be counted or controlled identifying vehicles
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
  • G07C9/00—Individual registration on entry or exit
  • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
  • G07C9/00309—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks
  • G07C2009/00555—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated with bidirectional data transmission between data carrier and locks comprising means to detect or avoid relay attacks
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
  • G07C9/00—Individual registration on entry or exit
  • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
  • G07C2009/00753—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys
  • G07C2009/00769—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means
  • G07C2009/00793—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means by Hertzian waves
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
  • G07C9/00—Individual registration on entry or exit
  • G07C9/00174—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys
  • G07C2009/00753—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys
  • G07C2009/00769—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means
  • G07C2009/00801—Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys operated by active electrical keys with data transmission performed by wireless means by acoustic waves
• • G—PHYSICS
  • G07—CHECKING-DEVICES
  • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
  • G07C2209/00—Indexing scheme relating to groups G07C9/00 - G07C9/38
  • G07C2209/60—Indexing scheme relating to groups G07C9/00174 - G07C9/00944
  • G07C2209/61—Signal comprising different frequencies, e.g. frequency hopping

Definitions

• the present invention relates to an access system, in particular a passive access system for vehicles.
• the Communication protocol uses a radio frequency interface to carry the transmitted data.
• the radio frequency (RF) interface has a limited area to ensure that the communication link is broken when a key-held person moves away from the immediate vicinity of the vehicle.
• the aim of the present invention is to present a system which eliminates this problem or which at least offers an expedient alternative.
• the present invention provides an access system that includes an electronic key with a transmitter and a secure location where a receiver is located, the transmitter and the receiver being designed to communicate with each other for authentication data to exchange, characterized in that the transmitter transmits a signal, the receiver converts the transmitted signal into spectral data, and that the access system grants access to the secure location when the authentication data is transmitted if the spectral data match the spectral signature of the transmitter.
• the receiver can advantageously detect the presence of an amplifier station if the spectral data represent the use of a transmission characteristic of the amplifier station.
• the present invention also provides a method of granting access to a secure location, including:
• Comparison of the spectral data with a spectral signature of a transmitter Comparison of the spectral data with a spectral signature of a transmitter; and granting access to the secure location upon receipt of authentication data if the spectral data matches the spectral signature.
• Figure 1 is a schematic view of a preferred implementation of an access system - 10 being an attacking repeater station - showing the transmitted and received signals.
• Figure 2 is a schematic diagram of received signal strength versus frequency;
• FIG. 3 is a block diagram of the access system.
• a passive access system 2 includes the following: an electronic key 4 with a transmitter 6 and an induction coil antenna 7, a base station 8 with a receiver 10 and an induction coil antenna 12.
• the base station 8 is accommodated in a secure location, such as a vehicle, and controls access to the secured location. If the key is moved within a certain range of the antenna 12 of the receiver 10, the receiver 10 excites the key 4, thereby causing the transmitter 6 to start transmitting to the receiver 10. Data are transmitted using RF signals, which establish a communication link between the key 4 and the base station 8.
• the data transmitted between the key 4 and the base station 8 are determined by a communication protocol, which the key 4 and the base station 8 follow, and which includes the transmission of authentication data from the key 4 to the receiver 10. Access to the secured location is provided by the
• Base station 8 is only permitted if the transmitted authentication data match the authentications stored by base station 8.
• a radio frequency amplifier station 16 can be between the key 4 and the base station 8 are performed.
• the repeater station uses amplifiers which have to amplify the signals transmitted by the system 2 considerably in order to break the distance between the key 4 and the base station 8.
• the amplifiers from any high gain amplifier stations 16 have one
• Transfer characteristic which is ideally linear, but in practice is never linear and runs out to a maximum gain.
• the amplifier station 16 will therefore interfere with the signal transmitted by the key 4, and the linearity of the amplifier station 16 determines the level of the signal interference effect.
• the linearity of the amplifier can be measured using a measurement known as a two-tone measurement to determine the third order intercept point of the amplifier.
• the third order catch point is a theoretical point where third order tones generated by mixing the transmitted fundamental tones intercept or disturb the fundamental tones in the sense that the third order signals emanating from the amplifier have the same amplitude as the basic signals or Have first order signals.
• the third-order interception point (IP3) of a radio frequency amplifier is a characteristic that can be determined by measuring the received signal strength of the third-order intermodulation tones received by the receiver.
• Passive access systems typically transmit data using a single RF tone.
• the access system 2 of the preferred implementation transmits two fundamental frequency tones 20 and
• the two RF tones 20 and 22 can be used to transmit data; however, the accuracy of the two-tone measurement subsequently performed by the receiver 10, such as described below may only be ⁇ 5%.
• the accuracy of the measurement is ⁇ 1% if the key 4 transmits the tones 20 and 22 with a constant amplitude for the two-tone measurement, and then the authentication data using RF modulation with one or both of the tones represent the carrier signal, transmitted.
• the receiver In response to the transmission of fundamental tones 20 and 22, the receiver will receive the tones and two third order intermodulation tones 24 and 26, as shown in frequency or spectral response 27 for receiver 10.
• the fundamental tones 20 and 22, as shown in Figure 2, are in adjacent ones
• An input signal strength indicator (RSSI) is generated by most FM receiving device semiconductors and can provide a measurement of the amount of energy received in each of the channels C1 to C4.
• the RSSI output generated by the receiver 10 is a voltage which is proportional to the in-band energy of the signal received in each of the measured channels C1 to C4. The RSSI for each channel can therefore be used to determine any variation, the third in the modulation tones
• Rules 24 and 26 are introduced by the introduction of an amplifier station 16, due to the non-linearity of the amplifiers of the amplifier station 16.
• the access system 2 is started, starting with a normal communication link between the key 4 and the base station 8 inside of the predetermined range, the RSSI being measured for each channel C1 or C4, and this being recorded as a spectral signature for the transmitter 6 of the key 4. All future transmissions can then be measured in a similar way to determine if any repeater station has been inserted into the system to vary the amount of third order intermodulation energy received. The difference received in the third order tones can also be used to determine a characteristic third order interception point to identify the attacking repeater 16. Discovery of an amplifier station 16 by the base station 10 will ensure that the base station 10 will refuse access to the secure location even if the authentication data is received as valid.
• the transmitter 6, as shown in FIG. 3, contains a switching logic which transmits two constant sound signals as soon as the key 4 is excited by the receiver 10.
• the switching logic can include two radio frequency oscillators 30 and 32 for the tones, the outputs of which in an antenna switch 34 for
• the switching logic may include a complex quadrature modulator that separates the generation of two tones by a multiple of that in the receiver
• the receiver 10 includes an FM receiver 36 connected to the antenna 12, an analog-to-digital converter 38, a microcontroller 40 and a frequency-synthesized local oscillator 42.
• the microcontroller 40 is programmed to control the frequency synthesizer 42 and to process data received by the A-D converter 38.
• Frequency synthesizer is used to select the frequency channels to be processed by FM receiver 36 which, as discussed above, produces RSSI output for each of the four channels C1 through C4.
• the RSSI output for each channel is routed to the AD converter for conversion into a binary word for processing by microcontroller 40.
• Microcontroller 40 treats the binary word as spectral data representative of the energy received in each of channels C1 through C4, and then uses the spectral data for comparison with a previously stored spectral signature for the transmitter 6.
• the system 2 is started by moving the key 4 within the predetermined range of the antenna 12 so that the key 4 is excited and causes the two fundamental tones to be transmitted.
• the spectral data received by the microcontroller 40 are then stored as a spectral signature of the transmitter 6 for future comparison for all subsequent communications between the key 4 and the receiver 10.
• the key 4 and the base station 8 accordingly carry out the following steps if a communication connection is subsequently established:
• the frequency synthesizer 42 selects the four channels C1 through C4 and the FM receiver 36 produces an RSSI output for each of the channels.
• the microcontroller 40 receives and processes the spectral data necessary for the received signal levels for each of the Channels are representative and this is compared to the stored spectral signature.
• the microcontroller 40 will cause it Base station 10 to abort the authentication procedures and prevent access to the secured location, (v) the amount of deviation of the received spectral data from the spectral signature is recorded for subsequent analysis to determine a characteristic third order trap, so that the attacking repeater station 16 can be identified. The number of attacks by repeater 16 can also be stored. (Vi) If base station 10 subsequently detects an authorized user and allows authorized access, microcontroller 40 causes an alert to be generated to indicate that an attack has been attempted.
• the warning signal can be in the form of a word display, a warning lamp or a sound signal which is generated at the secure location, ie the vehicle.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Computer Networks & Wireless Communication (AREA)
• Computer Security & Cryptography (AREA)
• Signal Processing (AREA)
• Lock And Its Accessories (AREA)
• Near-Field Transmission Systems (AREA)
• Selective Calling Equipment (AREA)
• Mobile Radio Communication Systems (AREA)
• Data Exchanges In Wide-Area Networks (AREA)

Priority Applications (5)

Applications Claiming Priority (4)

Publications (2)

Family

ID=25622628

Family Applications (1)

Country Status (9)

Cited By (7)

Families Citing this family (7)

Family Cites Families (14)

• 1999
  • 1999-06-08 AU AU33933/99A patent/AU743933B2/en not_active Ceased
  • 1999-07-16 DE DE59903476T patent/DE59903476D1/de not_active Expired - Lifetime
  • 1999-07-16 BR BR9912267-7A patent/BR9912267A/pt not_active IP Right Cessation
  • 1999-07-16 ES ES99947208T patent/ES2188244T3/es not_active Expired - Lifetime
  • 1999-07-16 WO PCT/DE1999/002178 patent/WO2000005696A2/de not_active Ceased
  • 1999-07-16 EP EP99947208A patent/EP1099204B1/de not_active Expired - Lifetime
  • 1999-07-16 KR KR1020017000713A patent/KR100686903B1/ko not_active Expired - Lifetime
  • 1999-07-16 JP JP2000561602A patent/JP4448618B2/ja not_active Expired - Lifetime
  • 1999-07-16 US US09/744,288 patent/US6765473B1/en not_active Expired - Lifetime

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