Abstract: Cloud computing is an innovative concept that has carried a paradigm shift into the IT industries. Security is the most critical issue in cloud computing. In security, authentication is the one of the important parameters to be addressed. Authentication is a key mechanism to establish proof of identities to get the sources from any type of system. Traditional security system does not provide enough security for the data which is stored in the cloud computing environment. This paper proposes a mechanism to improve the security in cloud using Authentication as a Service (AaaS). The paper provides a brief survey of existing authentication mechanisms. The proposed novel AaaS is used to ensure security in public cloud environment. The proposed mechanism is provided as an authentication service from a Cloud Service Provider (CSP). The AaaS identifies the users verify different level of authentication.

Keywords: Cloud Computing; Authentication; User Authentication System (UAS), Key Generating System (KGS).