Remarks on a Hypersphere Oriented Multiparty Key Agreement Protocol

Many modern network applications are based upon a multiparty communication model where participants are organized as a peer group. Especially, the communication medium in a wireless network is broadcast in nature, which facilitates group oriented applications like shared whiteboard. Given the openness of today´s network, providing privacy for peer groups is a critical design issue. For example, the broadcast nature of wireless networks implies that traffic sent over the air can be easily captured. Therefore, security services like traffic encryption and key management are essential to upper layer applications. In this paper we study a multiparty key agreement protocol based on the hyperspherical equation, in which each participant fairly contributes to the final radius of a virtual hypersphere. We reveal some undesirable design points in the scheme, as well as some serious security defects. We show that the protocol is vulnerable to attacks and thus is unsuitable for practical adoption.