US Patent 9294270 Detection of stale encryption policy by group members

Various techniques that allow group members to detect the use of stale encryption policy by other group members are disclosed. One method involves receiving a message from a first group member via a network. The message is received by a second group member. The method then detects that the first group member is not using a most recent policy update supplied by a key server, in response to information in the message. In response, a notification message can be sent from the second group member. The notification message indicates that at least one group member is not using the most recently policy update. The notification message can be sent to the key server or towards the first group member.