Multicast is an important communication method used in many emerging multimedia networking applications. Providing efficient security method to support the distribution of multimedia multicast is a challenging issue, since the group membership in such applications requires dynamic key generation and updation which takes more computation time. Moreover, the key must be sent securely to the group members. In this paper, we propose a new Key Distribution Protocol that provides more security and also reduces computation complexity. To achieve higher level of security, we use Euler's Totient Function φ(n) in the key distribution protocol. Therefore, it increases the key space while breaking the re-keying information. Two major operations in this scheme are join and leave operations for managing group memberships. An N-ary tree is used to reduce number of multiplications needed to perform the member leave operation. Using this tree, we reduce the computation time when compared with the existing key management schemes. © 2010 IEEE.