The Cloud Computing is a model to enable service ubiquitous, expedient and on-demand of users. It provides network access to a pool of computing resources like networks, servers, data storage, and applications. Cloud is large pool of resource and services through which we can get service or resource whenever needed by paying amount used. Cloud provides services though mobile phones, laptops and personal digital assistants. Security has emerged as one of the most important obstacle to faster and pervasive adoption of virtualization or cloud computing. The main troubling element of the security of the cloud is the EDoS attacks, which make the shared resources on the network unreachable to the user to make own profit or to make loss for others. So here, this paper will propose a defense mechanism against the EDoS attacks which is known as Secure Key Exchange. This paper proposed a mechanism to overcome the effects of EDoS attack by using a secure key Exchange to identify the legitimated users and filter the data coming from unauthorized user. Keywords: Cloud computing, Cloud-Sim, DDoS, EDoS attack, NetbeansCite this Article Shikha Vashisht, Mandeep Kaur. Mitigating Economic Denial of Sustainability in a Cloud Environment by Using Key Exchange. Journal of Network Security. 2015; 3(3): 9–16p.