Securing code update is essential for military and health care applications. The functionalists of the sensor nodes in military and health monitoring region depend on their environmental conditions. The sensor nodes will be divided into different multi cast groups based on their location. For each multi cast group a different code update will be sent. We have developed a scheme for secure code update for multi-cast groups.
In order to securely communicate the code update for each multi cast group, a key agreement protocol is developed. This protocol provides confidentiality and immediate authentication. The Protocol is implemented on Tiny OS platform, tested using Tossim simulator and evaluated the Performance. SCUMG protocol is resilient to malicious code update by compromised nodes and provides security against various attacks.