IR-CP-ABE: Identity Revocable Ciphertext-Policy Attribute-Based Encryption for Flexible Secure Group-Based Communication

Ciphertext-Policy Attribute-Based Encryption (CP-ABE) is an access control mechanism over encrypted data and well suited for secure group-based communication. However, it also suffers from the following problem, i.e., it is impossible to build all desired groups. For example, if two group members have exactly the same attributes, how to construct a group including only one of the two members? Obviously, attributes alone cannot distinguish these two members, therefore existing CP-ABE solutions do not work. To address this issue, in this paper, we present a new CPABE scheme (called IR-CP-ABE) that incorporates an Identity-based Revocation capability. With IR-CP-ABE, an access policy will be constructed by not only group members’ attributes but also their identities. To build a group, first, build a candidate group based on all desired group members’ attributes; second, remove undesired members by revoking their identities. By evaluating the security and efficiency of a proposed construction, we show that the IR-CP-ABE scheme is secure and efficient for practical applications.