Wireless Body Sensor Network (WBSN) faces several security problems such as loss of information, access control and authentication. As WBSN collects vital information and operates in unfriendly environment, severe security mechanisms are needed in order to prevent the network from anonymous interactions, authentication is the initial steps towards providing security. An enhanced authentication scheme prevents the system from imposters effectively. In this paper, a novel authentication using identity-based group signature (IBGS) protocol has been proposed to provide security to the WBSN. The proposed method employs identity-based group signature algorithm between biosensors and group manager (GM). An extensive set of experiments were carried out and the results are examined interms of computation cost and energy consumption.