Cloud computing is increasing its importance due to the services and IT resources provided by the cloud service providers. There are numerous advantages in cloud computing like highly scalable, low cost and high availability. But the data security and privacy is a major concern in cloud computing. Sharing the resources and storing the data in cloud is the major application in cloud computing. To protect the data in cloud, against unauthorized access, modification and denial of service etc. The biggest challenge in cloud is storing and sharing the sensitive data. In this paper, we have discussed symmetric algorithms, asymmetric algorithms, hash algorithms for security purpose and comparison of algorithms for securing data in different deployment models of cloud. In symmetric we have discussed AES, Fully Homomorphic Encryption, Blowfish, GLEnc, and asymmetric algorithms are DIFFE-HELLMAN, QKD-NAE Technique, RSA Cryptosystem, Identity Based Encryption. In hash few of the algorithms that has been discussed in this paper are MD5, SHA.

Cloud Computing, Data Security, Symmetric Encryption, Asymmetric Encryption, Hash function

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