A method is provided for authenticating an occupant within an interior of a vehicle. The vehicle includes a camera which is configured to monitor the interior of the vehicle, and a processing device being configured to process image or video data provided by the camera. Characteristic features are determined being visible via the camera, and authenticating image or video data are captured via the camera while an occupant is present within the interior of the vehicle. Via the processing device, face recognition and liveliness check are performed for the occupant based on the authenticating image or video data, and an identification degree of the characteristic features is determined within the authenticating image or video data. Based on the face recognition, the liveliness check and the identification degree it is determined whether an authentication of the occupant is to be accepted.