Passive liveness detection is a method that does not require any specific actions from the user. Therefore, it is possible to perform passive LD without the user’s interaction, by focusing on usability.
Active liveness detection requires the user to react in a certain way. In particular, it requires a user to intentionally confirm his or her presence by interacting with the system (e.g. by nodding) and is therefore particularly useful for applications requiring user consent putting high importance on data privacy.
For fighting attacks at the application level, e.g. through the injection of modified camera streams, challenge-response mechanisms can be utilized to reject prerecorded videos/deepfakes.
A challenge-response system requires the user to correctly respond to a specific action prompted by the ‘challenge’.
A challenge-response system is the most effective means to ensure user consent protecting both system integrity and data privacy. In a typical face application with challenge-response, the user is prompted to turn the head in one or more random directions. Only when the requested head directions were followed by the user correctly, the challenge-response is considered successful. The more challenges used, the higher the level of security, as it is more challenging for an attacker to have a video or deepfake recording showing exactly these head movements.
In the case of BioID, the user is prompted to turn their head in the specified direction (this is one challenge).
The requested head direction could be: Either up, or down, or left or right.