Wieczorek, F.F.WieczorekKrauß, C.C.KraußSchiller, F.F.SchillerEckert, C.C.Eckert2022-03-122022-03-122012https://publica.fraunhofer.de/handle/publica/37880810.1007/978-3-642-33678-2_132-s2.0-84867593322In this paper, we present an approach to secure fieldbus communication of automation systems used in security-critical applications. We propose a protocol that applies a scheme combining a stream cipher and a Message Authentication Code (MAC) to ensure integrity, confidentiality, authenticity, and freshness of transmitted telegrams over a fieldbus while maintaining real-time constraints. The security discussion shows that the protocol is secure against an adversary attacking the fieldbus communication. A first proof-of-concept implementation for the EtherCAT fieldbus protocol is implemented to perform some initial runtime analyses.en003conference paper