A network node and a method of updating and distributing secret keys in a distributed network is suggested. The network comprises a plurality of nodes connected to a shared medium of the distributed network. Each node of the plurality of nodes is member of at least one group of a plurality of groups. Each group is associated with a secret group key. Each node of the plurality of nodes stores only the one or more secret group keys, of which it is member. A first node of the plurality of nodes generates an authenticated update key request. The authenticated update key request comprises an indication of a membership, of which the first node is member. The first node broadcasts the authenticated update key request on the shared medium of the distributed network. Each remaining nodes of the plurality of nodes receives the authenticated key update.