Identity-based Broadcast Group-oriented Encryption from Pairings

In this paper, we formalize the notion of identity-based broadcast group-oriented encryption scheme and present a construction for it based on Gentry's IBE scheme. In our new scheme, the broadcaster could encrypt the message using the designated receive group's identity and any receiver in the designated group can independently decrypt the ciphertext. The newly proposed scheme has the following merits: Every member of the receiving group needs to keep only one private key; Both ciphertexts and system parameters are of constant size; A sender can send a secure message just by using the receive group's identity information, even before the receiver in the designated group obtains his private key from a PKG.