A method for safely controlling a medical device via an input unit using a verification unit, the input unit communicating with the verification unit via a communication channel (56a, 56b), the method comprising the steps of - first detecting, by the input unit, of a first actuation at a first actuation point within a release area on the input unit, wherein the first actuation is a touch and a maintaining of the touch, - first sending, from the input unit to the verification unit, of a request for unambiguous context information that establishes an unambiguous association between the actuation on the input unit and the verification unit, - generating, by the verification unit, the context information, - second sending, by the verification unit to the input unit, of the context information, - second detecting, by the input unit, of a second actuation that follows the first actuation while continuously maintaining the touch, the second actuation being a movement from the first actuation point to a second actuation point within a control area on the input unit while continuously holding the touch, and - controlling the medical device with the following repetitive steps: - third detecting, by said input unit, of a third actuation, said third actuation being a displacement within said control area while continuously holding said touch, - third sending, from the input unit to the verification unit, of a control message comprising a control command, identification information and displacement information, wherein the control command is associated with the control area, the identification information comprises the context information or an information derived from the context information, and the displacement information comprises information in which the length and direction of the displacement is contained or may be determined therefrom, - first checking, by the verification unit, whether the displacement information of at least a subset of the third actuations performed shows that the displacement on the input unit follows a predetermined shape, - second checking, by the verification unit, whether the identification information corresponds to the context information, and - fourth sending, by the verification unit to the medical device, of the control command or a command derived from the control command when the first checking and the second checking have been completed positively. - first detecting, by the input unit, of a first actuation at a first actuation point within a release area on the input unit, wherein the first actuation is a touch and a maintaining of the touch, - first sending, from the input unit to the verification unit, of a request for unambiguous context information that establishes an unambiguous association between the actuation on the input unit and the verification unit, - generating, by the verification unit, the context information, - second sending, by the verification unit to the input unit, of the context information, - second detecting, by the input unit, of a second actuation that follows the first actuation while continuously maintaining the touch, the second actuation being a movement from the first actuation point to a second actuation point within a control area on the input unit while continuously holding the touch, and - controlling the medical device with the following repetitive steps: - third detecting, by said input unit, of a third actuation, said third actuation being a displacement within said control area while continuously holding said touch, - third sending, from the input unit to the verification unit, of a control message comprising a control command, identification information and displacement information, wherein the control command is associated with the control area, the identification information comprises the context information or an information derived from the context information, and the displacement information comprises information in which the length and direction of the displacement is contained or may be determined therefrom, - first checking, by the verification unit, whether the displacement information of at least a subset of the third actuations performed shows that the displacement on the input unit follows a predetermined shape, - second checking, by the verification unit, whether the identification information corresponds to the context information, and - fourth sending, by the verification unit to the medical device, of the control command or a command derived from the control command when the first checking and the second checking have been completed positively.