Multimedia Messaging Service Encryption And Transmission Mechanism Based On Android System

Since China Mobile’s3G coverage especially smart phone has rapidly expand,increasing number of mobile multimedia services become users’ favorites. As one ofthe important mobile multimedia services, multimedia messaging service (MMS) notonly benefits cellphone users, but also profits network operators, content and servicesproviders. However, the MMS involves personal privacy which may cause users’privacy leak due to self-awareness deficit or security vulnerabilities exits in mobilenetwork. The leakage of personal sensitive information could bring users unnecessaryloss, even used by lawbreaker. Therefore, it is particularly important to do securityresearch of MMS whether to protect users’ privacy or to maintain the integrity ofoperators.After analyzed the existing encapsulation protocol of MMS, this paper proposesan algorithm based on the characteristics of the PDU (protocol data unit) of MMS.The algorithm encrypt the PDU separately, the header of the data field and the SMILpresentation of MMS as one part, and the attachment of the MMS as the other one.First, we scramble the header of data field and the SMIL field. Second, we use thescrambled data to encrypt the attachment field in XOR operation. Third, we encryptthe scrambled data of step one in AES. Finally, we encrypt the length of the scrambleddata in AES, and add it into the end of the cryptographic PDU. The algorithm of thispaper is advantageous as follows: first, we encrypt the generic MMS PDU separatelyand mixed up each part of it, this make it more difficult when brute force; second, wedouble encrypt the key information, using scrambling and AES algorithm; third, wemodify the existing encapsulation protocol of MMS PDU, added the key encryption length information in order to separate each part when decrypt. The Encryptionmethod proposed in this paper can encrypt the PDU of MMS very well, whichprovided a reliable guarantee for the safe transmission of MMS. But the method alsobrought the problem of key management which we couldn’t be avoided it, how tomanage the key still requires further research.