Abstract: Despite that existing data sharing systems in untrusted storage propose to encrypt data before sharing, the multiparty access control of encrypted data has become a challenging issue. In this, a secure data sharing based on cipher text-policy attribute-based proxy re-encryption and secret sharing. In order to protect user's sensitive data, this allows users to customize access policies of their data and then outsource encrypted data to the service provider. In this a multiparty access control model, which enables the disseminator to update the access policy of cipher text if their attributes satisfy the existing access policy. Further, a partial decryption construction in which the computation overhead of user is largely reduced by delegating most of the decryption operations to the service provider. Itís also provide check ability on the results returned from the service provider to guarantee the correctness of partial decrypted cipher text. Moreover, in this presents an efficient attribute revocation method that achieves both forward and backward secrecy. The security and performance analysis results indicate that is secure and efficient in untrusted storage.

Keywords: Encrypt, Cipher text, Policy, Re-encryption, Secret sharing.