Wireless body area networks (WBANs) are a key eHealthcare technology that allows patient's essential data to be together from the carrier or implantable biosensors. However, the protection and privacy of collected data is a major unresolved issue, as challenges stem from stringent resource constraints on biosensors and the high demand for security/privacy and practicality. Authentication protocol using a digital signature algorithm with a challenge response protocol that offers effective WBAN authentication. Based on public key infrastructure, In this paper group biosensor nodes (BNs) first, generate their publicprivate keys. The Designed Authorized Registrar (AR) generates the identifier code (gID) of the group biosensor identifier, the group identification tag, and the group secret key. Each group biosensor node (BN) retains its private key with signing ID. These parameters can only be provided by members who can sign and provide data authentication and non-retrieval for data transmission between biosensors. The signing protocol for the response identification signal with overlapping logical swap operation is proposed to guarantee that the signer receives a key group that is secure and prevents the making of false statements in the eHealthcare system.