Design And Implementation Of A Secure Communication System Based On Android

With the high-speed development of Internet and the rapid increase of smartphone users of the Android platform, various applications based on Android platform become richer and more colorful.However, due to its openness,the security problem of the mobile terminal based on Android is increasing.The end users use the sms application of the mobile phone to plain text messages, private pictures and bank card account,which involved users' privacy data.However,These sms applications do not provide confidential transmission function, unable to ensure the secure transmission of private data.In addition, the demand for IP phone is also increasing,but the voice data of IP phone transmits through the network also faces all kinds of network security threats.To this end, the thesis around the two mainstream applications-secret sms and secret phone started the research.In order to solve the problem of secret phone, the thesis use the public key cryptography to complete key agreement. According to the characteristics of SIP protocol, the thesis add the appropriate header field in the sip message header to complete key agreement in the process of session connection.In the process of sending and receiving voice data, the thesis use the symmetric encryption algorithm to encrypt and decrypt voice data. Different sessions use different session key to encrypt voice data,so it can guarantee the secure transmission of voice data.In order to solve the problem of secret sms, the thesis send the session key request message to the management center to complete session key agreement. Session key request message only pass the session key index,so one message can complete key agreement,saving the cost of sms. In addition, the thesis design the message database to realize the encryption storage of all sms and use the symmetric encryption algorithm to encrypt and decrypt messages to ensure the secure transmission of messages.Also,the secret sms supports local and remote destroy.when the phone is lost or stolen,the management center send the remote destroy command to remove all the sensitive data of the phone.Finally, the thesis have implemented the security communication prototype system based on the Android platform and tested the prototype system.The result shows that the secure communication system can ensure the secure transmission of voice and message data.