The applications on handheld devices are involved in some critical information exchange. This thesis report investigates which concepts exist to shelter software from modification and how the communication of these applications running on a handheld device over public mobile network can be made more secured. This report highlights how a smart card can facilitate to enhance the security of the software running on it particularly for handheld devices. It also discusses the issues and threats to smart cards. Furthermore it proposes a solution based on the specified scenario. The...