User Authentication in Cloud Computing

As Cloud Computing has been spreading widely, users and service providers enables to use resource or service cheaply and easily without owning all the resource needed. However, Cloud Computing has some security issues such as virtualization technology security, massive distributed processing technology, service availability, massive traffic handling, application security, access control, and authentication and password. User authentication among them requires a high-quranteed security. Hence, this paper would like to discuss technologies of access contol and user authentication briefly and look at the problems inside.