The invention relates to a communication network having at least one network element (NE), via which data associated with the communication are conducted. The method comprises the following steps: securing, by means of a first cryptographic security function, the data (D) that are transferred from at least one first communication device (PLC1) to at least one second communication device (PLC2), providing a second cryptographic security function, which secures, between a communication device and a network element, messages that are conducted from the first communication device to the at least second communication device via the at least one network element and that contain the data, providing a checking function by means of the at least one network element, which checking function checks the authenticity and/or integrity of the messages on the basis of the second security function, continuing (6) or stopping (5) the communication in accordance with the result of the check (4) by the checking function, wherein, if the communication is continued, the data remain secured by means of the first security function until the data are received by the at least second communication device.