Ubiquitous Technologies in eHealthcare systems are playing a vital role to perform a non-stop monitoring of patients' health in hospitals or outpatient. The application of eHealthcare System towards wireless sensor networks such as ECG, voice over IP and audio/video conferencing, location-aware and ambient intelligence require the support of mobile nodes or node groups. Furthermore, medical staff moves close to patients and collects their monitoring body parameters through their wireless devices. Thus, in such situation, the lack of network connectivity is not admissible or should at least be time bounded, e. g. mobile nodes cannot be disconnected from the rest of the WSN for an undefined period of time. In this paper, we propose a hybrid and fast authentication protocols that support fast handoff for real-time applications aforementioned. The proposed protocol is based on RSS measurement and on public key cryptography with Diffie-Hellman algorithm which provides security against both leakage-resilience of private keys on untrustworthy. The performance analysis shows that our proposed authentication protocols are efficient and resilient to various kinds of attacks.