Securing method, interrogation unit and securing system for implementing the securing method

• US 7,034,676 B2
• Filed: 04/04/2001
• Issued: 04/25/2006
• Est. Priority Date: 04/19/2000
• Status: Expired due to Fees

• Current Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Original Assignee: Conti Temic Microelectronic GmbH (Continental AG)
• Inventors: Haas, Heinrich, Schuler, Rolf, Knepper, Udo, Mueller, Karlheinz
• Primary Examiner(s): Mullen, Jr., Thomas J.
• Assistant Examiner(s): HUNNINGS, TRAVIS R
• Application Number:
  US10/258,005
• Publication Number:
  US 20030117259A1
• Time in Patent Office: 1,847 Days
• Field of Search: 340/539.1, 340/5.63, 340/10.1, 340/5.61, 340/10.2, 340/5.26
• US Class Current: 340/539.1
• CPC Class Codes: B60R 25/00 Fittings or systems for preventing or indicating unauthorised use or theft of vehicles locks for vehicles E05B77/00-E05B85/00
• CPC Class Codes: G07C 2009/00555 comprising means to detect or avoid relay attacks
• CPC Class Codes: G07C 9/00309 operated with bidirectional data transmission between data carrier and locks

Abstract

In a method for securing an object against unauthorized use, an interrogation unit (1) transmits an interrogation signal (s) and tests whether a response unit (2), which is to be carried by an authorized user, responds to the interrogation signal with a response signal (r) that contains as information a code authorized for desecuring a security device (3). If so, the security device is desecured. The securing method shall prevent unauthorized persons from establishing a radio link via relay stations between the interrogation unit (1) and the response unit (2) for providing the authorized code via this radio link without being noticed by the authorized user. The securing method prevents the desecuring of the security device (3) if the signal transit time of a signal transmitted as the interrogation signal (s) and received as the response signal (r) by the interrogation unit (1) during a monitoring time interval (t4–t5) is greater than a prescribed value. The method is carried out in a keyless security system for securing motor vehicles against unauthorized use.

Claims

1. A securing method for securing an object against unauthorized use, comprising:

transmitting an interrogation signal (s) by an interrogation unit (1) allocated to the object,

by a response unit (2) allocated to a user, responding to the interrogation signal (s) by transmitting a response signal (r),

testing whether the response signal contains as information an authorization code authorized for desecuring a security device (3), and

evaluating a signal transit time of the interrogation signal transmitted by the interrogation unit and the response signal transmitted by the response unit and received by the interrogation unit during a monitoring time interval (t4–

t5), and preventing a desecuring of the security device (3) if the signal transit time is greater than a prescribed value,

wherein

the interrogation signal (s) contains a first data bit sequence (Dl) as information and the response signal contains a second data bit sequence (D2) as information, wherein data bits of the first and second data bit sequences (D1, D2) are transmitted in bit cells of equal size, and the interrogation unit (1) simultaneously transmits data bits of the first data bit sequence (D1) and receives data bits of the second data bit sequence (D2) in the monitoring time interval (t4–

t5),

the first data bit sequence (D1) is composed of an interrogation code and a filler code adjoining the interrogation code, and

the response unit, for generating the second data bit sequence (D2), generates a response code (AO) from the interrogation code, wherein the response code is encoded bitwise with simultaneously received bits of the filler code and transmitted.

2. The securing method according to claim 1, wherein a time spacing between a bit cell of the first data bit sequence (Dl) transmitted by the interrogation unit (1) and a bit cell of the second data bit sequence (D2*) received by the interrogation unit is determined as the signal transit time.

3. The securing method according to claim 1, further comprising decoding the second data bit sequence (D2*) in the interrogation unit in a bitwise manner with simultaneously transmitted bits of the filler code, and preventing the desecuring of the security device (3) if a result of the decoding deviates from the authorization code.

4. The securing method according to claim 1, wherein the filler code is generated as a pseudo-random code.

5. The securing method according to claim 1, wherein the transmitting of the interrogation signal and the response signal between the interrogation unit (1) and the response unit (2) is carried out in a full duplex process.

6. An interrogation unit (1) for carrying out the securing method according to claim 1, comprising a transmit-receive unit (10) for transmitting the interrogation signal (s) and receiving the response signal (r) that is transmitted back by the response unit (2) in response to the interrogation signal (s) during the transmitting of the interrogation signal (s), and an evaluating device (11) for evaluating the response signal (r) and desecuring the security device (3), wherein the evaluating device (11) comprises transit time evaluating means for evaluating the signal transit time and preventing the desecuring of the security device (3) if the signal transit time is greater than the prescribed value.

7. The interrogation unit according to claim 6, wherein the evaluating device further comprises a decoder for decoding the second data bit sequence (D2*) in the interrogation unit in a bitwise manner with simultaneously transmitted bits of the filler code, and preventing the desecuring of the security device (3) if a result of the decoding deviates from the authorization code.

8. A security system for securing an object against unauthorized use, comprising the interrogation unit (1) according to claim 6 allocated to the object, and the response unit (2) that is mobile and that is allocated to the user and that cooperates with the interrogation unit (1).

9. The security system according to claim 8, wherein the response unit (2) includes a battery for a voltage supply.

10. The security system according to claim 8, wherein the response unit (2) is a battery-less operated transponder, to which energy for a voltage supply is provided inductively through the interrogation signal (s).

11. A method using the security system according to claim 8 for securing a motor vehicle against unauthorized use.