An Attribute-Based Signcryption Scheme to Secure Attribute-Defined Multicast Communications

We consider a special type of multicast communications existing in many emerging applications such as smart grids, social networks, and body area networks, in which the multicast destinations are specified by an access structure defined by the data source based on a set of attributes and carried by the multicast message. A challenging issue is to secure these multicast communications to address the prevalent security and privacy concerns, i.e., to provide access control, data encryption, and authentication to ensure message integrity and confidentiality. To achieve this objective, we present a signcryption scheme called CP_ABSC based on Ciphertext-Policy Attribute Based Encryption (CP_ABE) [2] in this paper. CP_ABSC provides algorithms for key management, signcryption, and designcryption. It can be used to signcrypt a message/data based on the access rights specified by the message/data itself. A multicast destination can designcrypt a ciphertext if and only if it possesses the attributes required by the access structure of the data. Thus CP_ABSC effectively defines a multicast group based on the access rights of the data. CP_ABSC provides collusion attack resistance, message authentication, forgery prevention, and confidentiality. It can be easily applied to secure push-based multicasts where the data is pushed from the source to multiple destinations and pull-based multicasts where the data is downloaded from a repository by multiple destinations. Compared to CP_ABE, CP_ABSC combines encryption with signature at a lower computational cost for signcryption and a slightly higher cost in designcryption for signature verification.