Information sharing, dissemination, digital libraries, and repositories are not new concepts. Open Access Initiatives make digital information more accessible to users. Access management is an important issue which illustrates the process of providing controlled, secure access to online resources which involves both authentication and authorization. Online security is one of the key services for the network infrastructure of digital repositories. Confidentiality and integrity of information cannot be ensured without a proper access management mechanism. This paper reviews available informatin on user authentications and authorization, and the authentication of digital materials is illustrated.