The subject innovation relates to a method with which a response to a request—said response having been ascertained by means of a communication terminal device can be securely transmitted to a data means, whereby the communication terminal device makes a selection from a plurality of response options. A specific key is associated with each of the response options, and the keys, which are in encrypted form, are received, together with the request, in the communication terminal device and they are decrypted in a means of the communication terminal device. On the basis of the selection made, the means ascertains the key that is associated with the selected response option, and the ascertained key is sent in a response message to the data means. The subject innovation also relates to a communication terminal device that is suitable for carrying out the method.