Communication security system and method

A communication security system includes a secure communication application module and a chip module. The communication security system is installed in a mobile device. Accordingly, the communication security system of the present invention allows mobile devices of users to encrypt and decrypt communication data between the users. A communication security method includes the steps of generating keys, requesting a key exchange by a first mobile device, receiving a key exchange by a second mobile device, receiving a key exchange by the first mobile device, activating a key by the second mobile device, activating a key by the first mobile device, and starting secure communication between the first and second devices. Thus, the encrypted communication can avoid theft and unauthorized falsification.