  Cloud computing is a revolutionary concept that has brought a paradigm shift
in the IT world. This has made it possible to manage and run businesses without
even setting up an IT infrastructure. It offers multi-fold benefits to the
users moving to a cloud, while posing unknown security and privacy issues. User
authentication is one such growing concern and is greatly needed in order to
ensure privacy and security in a cloud computing environment. This paper
discusses the security at different levels viz. network, application and
virtualization, in a cloud computing environment. A security framework based on
one-time pass key mechanism has been proposed. The uniqueness of the proposed
security protocol lies in the fact, that it provides security to both the
service providers as well the users in a highly conflicting cloud environment.
