Secured hash algorithm based encryption techniques

Attribute-based encryption (ABE) is a vision of public key encryption that allows users to encrypt and decrypt messages based on user attributes. In a typical implementation, the size of the ciphertext is proportional to the number of attributes associated with it and the decryption time is proportional to the number of attributes used during decryption. To reduce the decryption time in outsourced encryption method the user provides a transformation key to the cloud to translate any ABE ciphertext into simple ciphertext and it only incurs a small computational overhead for the user to recover the plaintext from the transformed ciphertext. We cannot guarantee that the cloud server will perform the transformation correctly. The proposed system introduces the Verifiable Outsourced Encryption so that the user can check the correctness of the transformation performed by the cloud server.