Authenticated public key broadcast encryption scheme secure against insiders’ attack

Broadcast encryption schemes have been studied in the past decades. Recently, insiders’ attack on the broadcast encryption scheme has been attracted attention among researchers. So, several broadcast encryption schemes with sender authentication have been proposed. However, since broadcast message size in previous schemes increases linearly at the number of target members, the previous schemes are not suitable for the group with large members. In this paper, we propose a new authenticated public key broadcast encryption scheme called $\omega$ ‐APKBE scheme. The proposed $\omega$ ‐APKBE scheme provides sender authentication property with a constant size broadcast message which is nonlinear on the number of target members. Hence, the proposed scheme is more compatible to the dynamic group with large members than the previous schemes.