Communications with interaction detection

Patent metadata

Field	Value
Publication number	US-9613475-B2
Application number	US-201514722800-A
Country	US
Kind code	B2
Filing date	May 27, 2015
Priority date	May 27, 2015
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

Aspects of the disclosure are directed to detecting interactions with signals, such as by an attacker attempting to gain access to a vehicle. Signal waveforms used for authentication are evaluated, for communications between respective circuits. Possible interaction by a third circuit is analyzed by detecting variations in characteristics of a leading portion of a data symbol relative to known characteristics of the leading portion of the data signal. A condition indicative of whether the signal waveform has been interacted with and retransmitted is determined, based on the detected variations. For instance, if the variations are indicative of a known type of variation induced by interaction and retransmission, such interaction and transmission can be detected. Where the determined condition is not deemed an attack, an output signal that provides vehicle access is generated based on the determined condition.

First claim

What is claimed is:

1. A method comprising:
communicating a signal waveform, having a data symbol with a leading portion and authentication information therein, between a first remote circuit and a second local circuit via which access to a vehicle is facilitated;
at the local circuit, detecting interaction, by a third circuit, with the signal waveform transmitted from the first remote circuit by
detecting variations in characteristics of the leading portion of the data symbol relative to characteristics of the leading portion of the signal waveform,
determining a condition indicative of whether the signal waveform has been interacted with and retransmitted, in response to the detected variations in characteristics being indicative of a type of variation induced by interaction and retransmission; and

generating an output signal that provides vehicle access based on the determined condition.

2. The method of claim 1 , wherein the access to the vehicle includes controlled unlocking of an entry door to the vehicle;
wherein determining the condition includes comparing changes in the leading portion of the data symbol with a retransmission profile that corresponds to changes induced by interaction and retransmission of the signal waveform,
further including determining a distance between the first remote circuit and the second local circuit based on the data symbol, and
wherein generating the output signal based on the determined condition includes,
generating the output signal in response to the determined distance being less than a predetermined threshold and the comparing of the changes in the leading portion of the data signal not matching the retransmission profile, and
inhibiting the output signal in response to the changes in the leading portion of the data symbol matching the retransmission profile.

3. The method of claim 1 , wherein characteristics of the leading portion of the signal waveform include expected characteristics of the signal waveform as uninterrupted by the third circuit, wherein determining the condition includes distinguishing between noise-based variations in the signal waveform and the variations induced by interaction and retransmission.

4. The method of claim 3 , wherein distinguishing between noise-based variations in the signal waveform and the variations induced by interaction and retransmission includes assessing a statistical component of the signal waveform relative to statistical components of known interaction and retransmission techniques.

5. The method of claim 3 , wherein distinguishing between noise-based variations in the signal waveform and the variations induced by interaction and retransmission includes cross-correlating the signal waveform with a template waveform and detecting the variations based on characteristics of the cross-correlation, relative to expected cross-correlation characteristics of the signal waveform.

6. The method of claim 3 , wherein distinguishing between noise-based variations in the signal waveform and the variations induced by interaction and retransmission includes:
cross-correlating the signal waveform with a template waveform,
computing a cumulative correlation as a sum of products of the cross correlation, and
detecting the variations based on the cumulative correlation.

7. The method of claim 6 , wherein
cross-correlating the signal waveform with a template waveform includes cross-correlating respective portions of each waveform pertaining to a common time period, and producing a product for each of the respective portions that are cross-correlated with one another, and
computing the cumulative correlation includes summing the products.

8. The method of claim 3 , wherein distinguishing between noise-based variations in the signal waveform and the variations induced by interaction and retransmission includes:
cross-correlating the signal waveform with a template waveform,
computing a cumulative correlation as a sum of products relating to the cross correlation, and
detecting the variations as being induced by interaction and retransmission based on a slope of values of the cumulative correlation, relative to an expected slope of values of a cumulative correlation of the signal waveform.

9. The method of claim 3 , wherein
detecting variations in characteristics of the leading portion of the data symbol includes identifying a position of a portion of the data symbol in which the detected variations occur, and
determining the condition is based on the identified position.

10. The method of claim 3 , wherein
detecting variations in characteristics of the leading portion of the data symbol is carried out for a plurality of symbols, and
determining that the signal waveform has been interacted with and retransmitted is based on the detected variations in each of the plurality of symbols.

11. The method of claim 3 , wherein detecting variations in characteristics of the leading portion of the data symbol relative to known characteristics of the leading portion of the data signal includes:
computing a ratio between a first likelihood function employing characteristics in the data symbol and a second likelihood function employing the known characteristics; and
detecting variations based on the computed ratio and a threshold indicative of variations.

12. The method of claim 1 , wherein detecting variations in characteristics of the leading portion of the data symbol relative to known characteristics of the leading portion of the data signal includes:
computing a ratio between a first likelihood function employing characteristics in the leading edge and a second likelihood function employing the known characteristics; and
detecting variations based on the computed ratio and a threshold indicative of variations.

13. The method of claim 12 , wherein computing the ratio includes computing the ratio based on a probability mass function characterizing timing of interaction within the data symbol.

14. The method of claim 1 , wherein generating an output signal that provides vehicle access based on the determined condition includes unlocking an entry door to the vehicle via the generated output signal, in response to the condition not being indicative of interaction and retransmission of the signal.

15. An apparatus comprising:
a first communication circuit configured and arranged to communicate a signal waveform, having a data symbol with a leading portion and authentication information therein, between a remote circuit and a local circuit via which access to a vehicle is facilitated;
a second detection circuit configured and arranged to detect interaction, by a third circuit, with the signal waveform transmitted from the remote circuit by
detecting variations in characteristics of the leading portion of the data symbol relative to characteristics of the leading portion of the signal waveform,
determining a condition indicative of whether the signal waveform has been interacted with and retransmitted, in response to the detected variations in characteristics being indicative of a type of variation induced by interaction and retransmission; and
a third output circuit configured and arranged to generate an output signal that provides vehicle access based on the determined condition.

16. The apparatus of claim 15 , wherein
the second detection circuit is configured and arranged to
determine the condition by comparing changes in the leading portion of the data symbol with a retransmission profile that corresponds to changes induced by interaction and retransmission of the signal waveform, and
determin

Assignees

• Nxp Bv

Inventors

• Zivkovic Zoran
• Li Liang

Classifications

• G07C2209/63

  Comprising locating means for detecting the position of the data carrier, i.e. within the vehicle or within a certain distance from the vehicle · CPC title

• G07C9/00174 Primary

  Electronically operated locks; Circuits therefor; Nonmechanical keys therefor, e.g. passive or active electrical keys or other data carriers without mechanical keys (mechanical locks with electric permutation E05B49/00; arrangements for sensing or reading record carriers G06K7/00; electronic switching H03K17/00) · CPC title

• G07C9/20 Primary

  involving the use of a pass · CPC title

• G07C2009/00555

  comprising means to detect or avoid relay attacks · CPC title

• G07C9/00007 Primary

  Physics · mapped topic