Boolean Searchable Attribute-Based Signcryption With Search Results Self-Verifiability Mechanism for Data Storage and Retrieval in Clouds

Storing and sharing confidential data in a public cloud storage system always raises privacy and security issues. When data is outsourced to a cloud server, the basic demands are secure and authenticated data storage, fine-grained data access control, secure search for the outsourced data, and search results verification. Attribute-Based Signcryption (ABSC) is a promising public-key cryptosystem for accomplishing data confidentiality and authenticity together. However, incorporating verifiable Boolean formula based keyword search and verifiable outsourced unsigncryption mechanisms into an ABSC is quite challenging. This is because the data user should be able to check whether the search result, returned by the untrusted cloud, has been correctly created. Precisely, the data user should be able to verify the correctness of the search, transform and signature verification operations involved in generating the search result. In this paper, for the first time, we propose a secure Searchable Attribute-Based Signcryption (sABSC) scheme that simultaneously supports (i) Boolean formula search over signcrypted data, (ii) keyword privacy, (iii) verifiable outsourced unsigncryption, and (iv) search results self-verifiability. In sABSC, each data user can efficiently verify the correctness of the search results returned by the cloud without interacting with any authority. We define more general security definitions of sABSC and provide rigorous security analysis. Performance evaluation exhibits that the proposed sABSC is practical.