Personal Health Records (PHR) are important health fields to store health information of a person. These records are stored on untrusted servers which makes secure data sharing a challenging task. In Cloud computing the cloud servers are usually operated by third-party, which are almost certain to be outside the trust domain of cloud users. Initially the PHR access policies should be applied on these storage servers, also the confidentiality and security of sensitive data should be well

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... d against them. Various Encryption techniques are applied to carry out these tasks-encrypted PHR's are stored on storage servers while retaining secret key(s) to the data owner himself, user access is granted by issuing the corresponding data decryption keys. The main challenges for encryption techniques include simultaneously achieving system scalability and fine-grained data access control and efficient user/key management. To put forward these challenging tasks, various-Attribute-Based Encryption (ABE) techniques are used. Fine-grained data access control is guaranteed on untrusted servers.