Functional broadcast encryption with applications to data sharing for cloud storage

Abstract Cloud storage services provide data owners an efficient and flexible way to share data. Among the shared data, some of them are very sensitive, and should be prevented for any leakage. Should users conventionally encrypt the data, however, flexibly sharing is lost. Public-key encryption with access control (PEAC) resolves this tension. Most of existing PEAC schemes only support the data owner to control either the parts of data to be accessed by other users (file-based PEAC), or the membership of users that access the entire data set (receiver-based PEAC). However, in reality a PEAC scheme with both file-based and receiver-based functionalities is required to ensure the efficiency, flexibility, and fine-grainess of the data sharing service. In this paper, we introduce a primitive of functional broadcast encryption (FBE). FBE is a manifestation of PEAC that enables a data owner to share a set of data files to a group of users, where only a specific subset of data files can be accessed and decrypted by a specific subgroup of users. We describe a construction for FBE based on indistinguishability obfuscation ( i O ). Security analysis demonstrates that the proposed scheme achieves selective IND-CCA security, and a comprehensive performance analysis shows the proposed scheme is efficient.