Abstract: An efficient and optimized secure group communication plays a vital role in many emergency communication. The operations on group key management protocol like joining or leaving the group dynamically and rekeying the group key when changes happen in the group are performed in many protocols. In the proposed system, a trust node is elected and a contributory group key is generated using the 24 bit color values (RGB) that provides a secure communication of messages among the group members in the dynamic environment through Diffie Hellman key exchange. The proposed system also reduces the cost of rekeying the group key when the mobility of the node increases. It was simulated to analyze the various issues related to group key management protocols like reliability, cost of contracting the group key when member join or leave the group dynamically, membership duration on re-keying overhead, inter-move variation on decryption/re-encryption overhead with member arrival duration. The above parameters are analyzed with respect to various other group key generation protocols and results are produced. The proposed system provides an optimized secure group key generation protocol for MANETs.