Cloud computing is a globalized concept and there are no borders within the cloud. Computers used to process and store user data can be located anywhere on the globe, depending on where the capacities that are required are available in the global computer networks used for cloud computing. Because of the attractive features of cloud computing, many organizations are using cloud storage for storing their critical information. The data can be stored remotely in the cloud by the users and can be accessed using thin clients as and when required. One of the major issue in the cloud today is data security in cloud computing. Storage of data in the cloud can be risky because of use of the Internet by cloud-based services which means less control over the stored data. One of the major concern in the cloud is how do we grab all the been ts of the cloud while maintaining security controls over the organizations' assets. Our aim is to propose a more reliable, decentralized lightweight key management technique for cloud systems which provides more e client data security and key management in cloud systems. Our proposed technique provides better security against Byzantine failure, server colluding and data modi cation attacks. Keywords: Cloud security; key management; server colluding attacks; Byzantine failure;