Efficient anonymous multi-receiver ID-based encryption with constant decryption cost

Anonymous multi-receiver identity (ID)-based encryption (anonymous MIBE) allows a sender to use the identities of multiple receivers to encrypt messages such that only the selected receivers can decrypt the messages while nobody, except the sender, knows who the other selected receivers are. Recently, several anonymous MIBE schemes were proposed. However, some security weaknesses were found in some of these schemes. Moreover, in the existing anonymous MIBE schemes, the decryption cost required for each receiver is linear in the number of selected receivers. In this article, we propose an efficient anonymous MIBE scheme and formally prove that it is semantically secure for both confidentiality and receiver anonymity. With compared to previously proposed anonymous MIBE schemes, our scheme has the best performance while offers provable security.