Abstract
In this paper, two custom communication applications are designed and modeled by using OPNET simulation platform. The first application only provides the clients plain text communication service but the second one ensures everyone to connect others securely by encrypting messages. In the related scenario, we conduct the simulation to collect and analyze all global statistics of two versions of the communication application respectively. The results of the analysis on the simulation is used to evaluate the feasibility of different encrypting schemes and the conclusion helps to develop more useful communication applications.