On key distribution in secure multicasting

Multicasting has been widely utilized for delivering messages from one sender to multiple recipients. Nowadays in some applications such as pay per view or video-conferencing systems, the messages delivered via multicasting should be available to authorized recipients only. Therefore, secure multicasting becomes an important design issue in a distributed environment. To achieve secure multicasting, all authorized recipients form a group and share a group key; messages should be encrypted by the key before they are multicasted. For the sake of security, we need a new group key if someone joins/leaves the group. Consequently, our goal is aimed at finding a way to distribute the new key securely and efficiently. We propose a new solution to the problem; we distribute new keys through a special function called the secure filter. Compared with related work, our solution requires less system resources to change group members.