Active liveness

Asking the user to blink, turn, or smile to prove they are live.

The app shows a prompt, such as "turn your head to the left," and checks that the person responds the way a live human would.

Challenge-response liveness requiring a directed user action during capture. A challenge-response check asks a question the system can verify, which here means a prompted movement, and then confirms the answer.

A typical active liveness check works like this:

1. The app asks the person to perform one or more actions.
2. The person performs them in front of the camera.
3. The system checks that the movement happened as requested and looks like a live face.
4. A pass lets verification continue, and a fail asks for a retry or declines.

Common challenges include:

• Blinking or smiling, which a still photo cannot do.
• Turning the head, which shows depth and a natural 3D shape.
• Following a moving prompt, which tests whether the face responds in real time.

Randomizing the order of challenges makes a prerecorded replay harder, since the attacker cannot know the request in advance.

Active liveness sits next to terms that are easy to mix up:

• Passive liveness reaches the same goal with no user action.
• Liveness detection is the umbrella term for both approaches.
• Drop-off measures how many people abandon the flow, which extra steps can raise.