SMS technology was not designed to transmit secure data; it does not provide built-in support for any security feature (e.g., authentication and confidentiality) between SMS communicators, in this book, a centralized secure messaging system (CSMS) is introduced. It allows the system clients to exchange highly secured messages exclusively via trusted third party (i.e. server). The main server contains a central database that holds clients' information. Depending on this information the server does the required message processing and forwards it to its final destination. The communication of...