Abstract
IEC 61850 is the present standard recommended for the power system substations. The transition to IEC 61850 challenges the classical approaches of substation engineers especially regarding ensuring a high level of trustfulness in the communication. This paper presents a method for detecting and blocking the injection of malicious or replicated messages in a digital substation. This addresses both sampled values and GOOSE packets. Moreover, an example of implementation is presented and validated on an experimental setup replicating the behavior of a digital substation.