Provable Secure Constructions for Broadcast Encryption with Personalized Messages

摘要

Broadcast encryption is an efficient way to send the broadcast messages, but, it does not yield a productive way to send the personalized messages to individuals. A broadcast encryption with personalized messages (BEPM) skillfully sends the broadcast message to a group of users together with the personalized messages to individual users. This article identifies constructional flaws in the BEPM scheme of Xu et al. and designs three BEPM constructions, namely, BEPM-I, BEPM-II and BEPM-III. BEPM-I, BEPM-III are selectively secure. Unlike the existing similar works, these schemes eliminate the need of storing public key and secret key for transmitting personalized messages. We emphasize that BEPM-III employs multilinear maps and achieves logarithmic size public parameter with increasing computation cost. More positively, BEPM-II achieves adaptive security with the parameter size and computation cost as in the existing BEPM. All our constructions have constant communication cost and proven to be secure in the standard security model under reasonable assumptions in generic group model. Furthermore, our schemes are fully collision resistant and flexible for adding and removing of users from the broadcast system.