An efficient identity-based proxy signcryption for secure broadcast

To our best knowledge, no identity-based proxy broadcast signcryption scheme is known despite of the broadcast communication and the ability of delegation is widely used in many hierarchical ubiquitous computing groups. In this paper, we describe the first identity-based proxy broadcast signcryption scheme(IBPBSC). The proposed scheme supports the dynamic broadcast signcryption while achieving the security properties as well as providing the ability of delegating the signcrypting capacity from an original signcrypter to a proxy signcrypter. It is also very efficient in the aspect of communication because the size of ciphertexts and private keys in the scheme is constant, regardless of the size of receiver set. In addition, we analyze the proposed scheme from efficiency and security points of view.