Method to secure the communication of components within self-service automats that are linked to each other by a bus system, having a transmitter and a receiver, characterized in that data are exchanged as tupels (C,A,R,N,Z) on the transport layer of the bus system where C are the message data M encrypted with an encryption key, A are the message data M authenticated with an authentication key, R represents the role of a component on the bus system of active or passive participants, N represents a message counter, Z represents a session counter.