Abstract: Aspects concern a method for authenticating a driver of a vehicle, comprising sending a request to a mobile phone to provide a selfie of a user of the mobile phone by means of the mobile phone, wherein the mobile phone is registered to receive orders for transport tasks, determining a time the user takes to provide a selfie in response to the request, sending additional requests to the mobile phone to provide selfies by means of the mobile phone if the determined time exceeds a predetermined threshold with a higher frequency than if the determined time does not exceed the predetermined threshold and performing authentication of the user as legitimate driver using selfies provided in response to the additional requests.