This book focuses on two of the most rapidly developing areas in wireless technology (WT) applications, namely, wireless sensors networks (WSNs) and wireless body area networks (WBANs). These networks can be considered smart applications of the recent WT revolutions. The book presents various security tools and scenarios for the proposed enhanced-security of WSNs, which are supplemented with numerous computer simulations. In the computer simulation section, WSN modeling is addressed using MATLAB programming language.