The present application relates to a methodology of verifying secret keys in a distributed network comprising a plurality of nodes connected to a shared medium. 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. A verification request is broadcast to the plurality of nodes and verification responses broadcast from the plurality of nodes are received. Each verification response comprises one code sequence for each logical group, of which the broadcasting node is member. Each code sequence of the verification request is generated on the basis of a secret group key associated with a respective logical group from a predefined data sequence. The code sequences are collected and the integrity of the plurality of nodes is confirmed by comparing the code sequences.