Method of detecting replay attacks in a fingerprint sensor system

A biometric system comprising:

• a fingerprint sensor;
• and
• a sensor controller in communication with the fingerprint sensor through an interface, wherein the sensor controller is configured to:
• generate a command set, the command set configured to cause the fingerprint sensor to conduct a scan of rows or columns of pixels to capture fingerprint data, wherein the command set includes a replay attack detection command,
• wherein the replay attack detection command causes the fingerprint sensor to repeat the scan of a set of pixels in a selected row or column to capture replay attack detection data;
• send the command set to the fingerprint sensor through the interface;
• receive the fingerprint data from the fingerprint sensor through the interface;
• and
• evaluate the fingerprint data for the presence of the replay attack detection data in conformity with the replay attack detection command,
• wherein the replay attack detection command is selected from the set of replay attack detection commands comprising:
• a repeat replay attack detection command causing the fingerprint sensor to repeat the scan of the set of pixels in a selected row or column without changing a bias supplied to the set of pixels;
• an under-bias replay attack detection command causing the fingerprint sensor to decrease a bias supplied to the set of pixels in the selected row or column to an insufficient level;
• an over-bias replay attack detection command causing the fingerprint sensor to increase a bias supplied to the set of pixels in the selected row or column to an excessive level;
• a pixel scan time adjustment replay attack detection command causing the fingerprint sensor to adjust the pixel scan time for the scan of the set of pixels in the selected row or column;
• and
• a gain change replay attack detection command causing the fingerprint sensor to change a gain supplied to a detected bias at the set of pixels in the selected row or column.

A method for detecting replay attacks in a fingerprint sensor system, the method comprising:

• generating a command set, the command set causing a fingerprint sensor to scan a plurality of pixels to capture fingerprint data, wherein the command set includes one or more replay attack detection commands each causing the fingerprint sensor to capture replay attack detection data from a shape of pixels selected from a set of pixels in a selected row;
• sending the command set to the fingerprint sensor;
• and
• receiving fingerprint data from the fingerprint sensor,
• wherein the one or more replay attack detection commands are selected from the set of replay attack detection commands comprising:
• a repeat replay attack detection command causing the fingerprint sensor to repeat the scan of the set of pixels in the selected row without changing a bias supplied to the set of pixels;
• an under-bias replay attack detection command causing the fingerprint sensor to decrease a bias supplied to the set of pixels in the selected row to an insufficient level;
• an over-bias replay attack detection command causing the fingerprint sensor to increase a bias supplied to the set of pixels in the selected row to an excessive level;
• a pixel scan time adjustment replay attack detection command causing the fingerprint sensor to adjust the pixel scan time for the scan of the set of pixels in the selected row;
• and
• a gain change replay attack detection command causing the fingerprint sensor to change a gain supplied to a detected bias at the set of pixels in the selected row.