This book delves into the critical role of authentication in safeguarding e-health systems, advocating for stronger authentication schemes and the development of robust security protocols to protect sensitive healthcare information. The book also explores the implementation and testing of mobile e-health applications, demonstrating how password-less authentication can streamline communication between patients and healthcare providers while enhancing security.   Recognizing the reliance of many mobile e-health systems on third-party service providers, this book proposes a two-tier mobile e-health system framework that eliminates the need for third-party servers, thereby strengthening the confidentiality of network transmissions. This book offers a forward-thinking solution to modern e-health security challenges, empowering healthcare systems to move beyond traditional password-based authentication and towards a safer, more efficient future.   This book is suitable for Postgraduate (Masters, PhD) & Researchers in the fields of computer science and information security.