Comment on an ID-Based Broadcast Signcryption Scheme
Jianhong Zhang, Qin Geng · 2009
Broadcast encryption is an important cryptographicaltechnique. It allows a center to deliver the encrypted datato a large set of users so that only a particular subset ofprivileged users can decrypt it. Most of previous broadcastencryption schemes only provide confidentiality, while theycannot provide authentication and non-repudiation. Recently,Li et.al proposed a broadcast signcryption schemeto achieve authentication and non-repudiation. And theyclaimed that their scheme was secure against outside attackand inside attack. Unfortunately, we show that their schemeis insecure by analyzing its security and cannot be againstoutside attack and inside attack. Thus, their scheme cannotachieve authentication and non-repudiation.