Abstract
Cloud computing has been developing rapidly over the last five years, although it has many advantages comparing with legacy systems, various issues are yet existing and becoming obstacles for business adoptions. The number one concern of these obstacles is always security (Kandukuri et al., 2009). This paper attempts to evaluate the authentication feature of Amazon Elastic Compute Cloud (EC2), which is one of the dominators in Cloud Service Providers. After inspecting different EC2's authentication techniques, the paper proposes some approaches to improve current authentication system. The approaches were proved to be secure and show a good promise for cloud computing security, especially authentication in the Cloud.