An Efficient and Secure Data Sharing Scheme for Ciphertext-Policy Attribute-based Signcryption for Cloud Storage Services

In this paper, an efficient retrievable attribute with Ciphertext-policy attribute-based signcryption with accountable and verifiable outsourced designcryption (CP-ABSc-AVODs) was proposed towards enable sharing of data in cloud in a secure manner. The cloud provides accurate control on data access, encryption and authenticity to data for granting confidentiality and integrity to personal messages. This protocol enables signing of message, depending on the access privileges given in tree structure mentioned embedded with the message. Users will be able to decrypt to get plaintext if and only if they have the necessary properties satisfying the structure specified for data access. In addition, CP-ABSc-AVODs provide access policy update functionality to decrypt unsigned or signed cloud storage server messages and redistribute user secret keys. The feature of access policy update in CP-ABSc-AVODs has no effect on the number of messages or its size received at the client site and hence there is a reduction in bandwidth and memory usage. The proposed protocol includes general attack resistance, message detection, data protection and fraud prevention. In addition, the proposed method’s performance is evaluated by comparing with other methods with respect to size of the key, functionality and time required for computation.