“Cloud Computing” a form of On-demand computing used by business peoples, organizations and institutions on pay –as-you basis. The Cloud Computing paradigm have many advantages such as availability, scalability, automated updates on software, enhanced collaboration and easily manageable, that makes it as an efficent medium for use. Security threat to its data stored in shared medium is a major concern. To ensure the authentication of the data many mechanisms were in use. Over past decades Cryptography is one most widely used technique for concealing data from third party. Symmetric key cryptography uses the similar key for both the encryption and decryption of messages. Instead, Asymmetric key cryptography uses two different types of keys. This paper discussed about the brief overview of algorithms and mechanisms done by the researchers regarding authentication and authorization issues in the asymmetric key scenario.

Cloud Computing, Authentication, Cryptography, Security

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