Detection of replay attack

Patent metadata

Field	Value
Publication number	US-11704397-B2
Application number	US-202017074743-A
Country	US
Kind code	B2
Filing date	Oct 20, 2020
Priority date	Jun 28, 2017
Publication date	Jul 18, 2023
Grant date	Jul 18, 2023

Abstract

In order to detect a replay attack in a speaker recognition system, at least one feature is identified in a detected magnetic field. It is then determined whether the at least one identified feature of the detected magnetic field is indicative of playback of speech through a loudspeaker. If so, it is determined that a replay attack may have taken place.

First claim

The invention claimed is:

1. A method of detecting a replay attack in a speaker recognition system, the method comprising:
receiving an audio signal comprising speech;
receiving a magnetometer signal;
determining a syllabic rate or an articulation rate of the speech;
detecting modulation of at least one feature of the magnetometer signal at the syllabic rate or the articulation rate;
determining based on the detecting that the at least one identified feature of the detected magnetic field is indicative of playback of speech through a loudspeaker; and
determining that a replay attack may have taken place.

2. The method of claim 1 , wherein the syllabic rate or the articulation rate of the speech are determined for speech detected at the same time as the magnetometer signal.

3. The method of claim 1 , wherein the determined syllabic rate or articulation rate is used to set a passband frequency range for detecting modulation of the at least one feature of the magnetometer signal.

4. A method as claimed in claim 1 , wherein the audio signal is received at substantially the same time as the magnetic field is detected, the method further comprising, if it is determined that the at least one identified feature of the detected magnetic field is indicative of playback of speech through a loudspeaker, determining that the audio signal may result from said replay attack.

5. A method as claimed in claim 1 , wherein the magnetometer signal is received from a magnetometer, the method further comprising:
performing a Discrete Fourier Transform on the magnetometer signal.

6. A method as claimed in claim 1 , comprising determining whether a detected pattern of variability of the magnetic field is indicative of a reference pattern associated with playback of a predetermined spoken phrase through a loudspeaker.

7. A method as claimed in claim 6 , wherein determining whether the detected pattern of variability of the magnetic field is indicative of a reference pattern associated with playback of a predetermined spoken phrase through a loudspeaker comprises:
comparing the detected pattern of variability of the magnetic field with a stored reference pattern.

8. A method as claimed in claim 7 , wherein the stored reference pattern corresponds to the predetermined spoken phrase, as spoken by a specific enrolled user, or as spoken by multiple speakers.

9. A method as claimed in claim 6 , wherein determining whether the detected pattern of variability of the magnetic field is indicative of a reference pattern associated with playback of a predetermined spoken phrase through a loudspeaker comprises:
passing the detected pattern of variability of the magnetic field to a classifier that has been trained with inputs obtained from playback of the predetermined spoken phrase through a loudspeaker.

10. A device comprising an apparatus as claimed in claim 9 , wherein the device comprises a mobile telephone, headset, an audio player, a video player, a mobile computing platform, a games device, a remote controller device, a toy, a machine, or a home automation controller or a domestic appliance.

11. A non-transitory computer readable storage medium having computer-executable instructions stored thereon that, when executed by processor circuitry, cause the processor circuitry to perform a method according to claim 1 .

12. An apparatus comprising processing circuitry and a non-transitory machine-readable medium storing instructions which, when executed by the processing circuitry, cause the apparatus to:
receive an audio signal comprising speech;
receive a magnetometer signal;
determine a syllabic rate or an articulation rate of the speech;
detect modulation of at least one feature of the magnetometer signal at the syllabic rate or the articulation rate;
determine based on the detecting that the at least one identified feature of the detected magnetic field is indicative of playback of speech through a loudspeaker; and
determine that a replay attack may have taken place.

13. The apparatus of claim 12 , wherein the syllabic rate or the articulation rate of the speech are determined for speech detected at the same time as the magnetometer signal.

14. The apparatus of claim 12 , wherein the determined syllabic rate or articulation rate is used to set a passband frequency range for detecting modulation of the at least one feature of the magnetometer signal.

15. An apparatus as claimed in claim 12 , wherein the audio signal is received at substantially the same time as the magnetic field is detected, the instructions further causing the apparatus to:
if it is determined that the at least one identified feature of the detected magnetic field is indicative of playback of speech through a loudspeaker, determine that the audio signal may result from said replay attack.

16. An apparatus as claimed in claim 12 , wherein the magnetometer signal is received from a magnetometer, the instructions further causing the apparatus to:
perform a Discrete Fourier Transform on the magnetometer signal.

17. An apparatus as claimed in claim 12 , the instructions further causing the apparatus to:
determine whether a detected pattern of variability of the magnetic field is indicative of a reference pattern associated with playback of a predetermined spoken phrase through a loudspeaker.

18. An apparatus as claimed in claim 17 , wherein determining whether the detected pattern of variability of the magnetic field is indicative of a reference pattern associated with playback of a predetermined spoken phrase through a loudspeaker comprises:
comparing the detected pattern of variability of the magnetic field with a stored reference pattern.

19. An apparatus as claimed in claim 18 , wherein the stored reference pattern corresponds to the predetermined spoken phrase, as spoken by a specific enrolled user, or as spoken by multiple speakers.

20. An apparatus as claimed in claim 17 , wherein determining whether the detected pattern of variability of the magnetic field is indicative of a reference pattern associated with playback of a predetermined spoken phrase through a loudspeaker comprises:
passing the detected pattern of variability of the magnetic field to a classifier that has been trained with inputs obtained from playback of the predetermined spoken phrase through a loudspeaker.

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Lesso John Paul

Classifications

• G06F21/32 Primary

  using biometric data, e.g. fingerprints, iris scans or voiceprints · CPC title

• G01R33/0094

  Sensor arrays · CPC title

• G06F21/554

  involving event detection and direct action · CPC title

• G10L15/24

  Speech recognition using non-acoustical features · CPC title

• G10L17/02

  Preprocessing operations, e.g. segment selection; Pattern representation or modelling, e.g. based on linear discriminant analysis [LDA] or principal components; Feature selection or extraction · CPC title