In Body Sensor Networks (BSNs) tiny biosensor nodes are deployed inside/outside of a human body to continuously monitor patient vital signs. BSNs face various challenges due to their constrained natured environment. These are the privacy of patient information, secure transmission of patient data using a public network, high overhead, and energy constraints. Although various researchers have worked in this domain but unable to cope with all these issues in one go. In this book, we propose five efficient and secure attribute-based schemes for BSNs that desirably covering the mentioned issues.