Key Management and Distribution for Securing Multimedia Multicasts

The distribution of identical data to multiple parties using the conventional point-to-point communication paradigm makes inefficient usage of resources. The redundancy in the copies of the data can be exploited in multicast communication by forming a group consisting of users who receive similar data, and sending a single message to all group users [1]. Access control to multicast communications is typically provided by encrypting the data using a key that is shared by all legitimate group members. The shared key, known as the session key (SK), will change with time, depending on the dynamics of group membership as well as the desired level of data protection. Since the key must change, the challenge is in key management- the issues related to the administration and distribution of keying material to multicast group members.

In order to update the session key, a party responsible for distributing the keys, called the group center (GC), must securely communicate with the users to distribute new key material. The GC shares keys, known as key encrypting keys (KEKs), that are used solely for the purpose of updating the session key and other KEKs with group members.