Abstract: A method of key management in a communication network that includes a plurality of groups with each group including one or several members authorized to have access to key-protected services is provided by an apparatus. The method includes determining when a member starts a switching action from one service to another. A time dependent quantity starting from the switching action is determined. The method includes determining that the member is a member of a switching group when the quantity is less than a threshold value is made, and when the quantity is larger than the threshold, determining that the member has decided to join a new group, and changing the appropriate access key(s).

Abstract: The present invention relates to a method of key management and to an apparatus (200) of communication network (100) comprising a plurality of groups (141, 142, 143), each group (141) including one or several members (132A, 132B, 132C) authorized to have access to key-protected services provided by the apparatus. According to the method, it is determined when a member (132A) starts a switching action from one service to another and it is determined a time dependent quantity starting from the switching action. The method further comprises, determining that the member (132A) is a member of a switching group (150) when the quantity is less than a threshold value, and when the quantity is larger than the threshold, determining that the member (132A) has decided to join a new group (142), and changing the appropriate access key(s).