The European Train Control System (ETCS) enables safe inter-European railway traffic. Keys are used to protect the mobile radio-based communication from the train to the trackside Radio Block Centre. In future, these keys will be exchanged via an automatic and secure key management system (Online KMS). The European railway operators have exchanged their views on best practices in the past months in the EUG KMS Expert Group under the lead of our colleagues Richard Poschinger and Roger Metz. The result of this work, the EUG KMS Guideline, has now been published on the EUG website and is available here.