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A SECURITY MODEL OF VOICE EAVESDROPPING PROTECTION OVER DIGITAL NETWORKS

 

TITLE A SECURITY MODEL OF VOICE EAVESDROPPING PROTECTION OVER DIGITAL NETWORKS
AUTHOR SATHAPORN KASSUVAN
DEGREE MASTER OF SCIENCE PROGRAMME IN COMPUTER SCIENCE
FACULTY FACULTY OF SCIENCE
ADVISOR SUPACHAI TANGWONGSAN
CO-ADVISOR CHOMTIP PORNPANOMCHAI
SUPATANA AUETHAVEKIAT
 
ABSTRACT
The purpose of this research is to develop a security model for voice eavesdropping protection over digital networks. The proposed model provides an encryption scheme and a personal secret key exchange between communicating parties, a so-called voice data transformation system, resulting in a real-privacy conversation. Operation of this system comprises two main processes. The first one is the personal secret key exchange to allow use of a key in the encryption process during the conversation. The other one is the encryption of G.729, G.723.1, G.726 or AMR encoded voice data in the conversation. In doing so, users can choose the option of encryption by themselves, that is, either all frame or partial frame encryption. In partial frame encryption or 1-to-M block encryption, the first block of each packet is encrypted while the remaining M-1 blocks are left unchanged, alternating like this until the end of the conversation. In this process, M is the number of blocks in each group of packets to be encrypted, possibly 1, 2, 3, 4, or 5, giving those who wish to tap the encrypted voice or apply a method of cryptanalysis to the conversation, a difficult task. The system prototype was implemented and tested based on its conceptual design. The results of the implementation indicate that the system can perform its function accurately as designed. Even in the case of 20% of the whole data being encrypted, the system could still provide speech security. Moreover, partial frame encryption would take less time than all frame encryption, which the experimental result yields quite satisfactorily. In this regard, the proposed system is suitable for effective use in voice eavesdropping protection over digital networks, without the requirement to change presently existing network systems. Also, it would be possible to extend this system to mobile phone networks or Internet networks for the sake of business purposes.
KEYWORD SECURITY MODEL / VOICE EAVESDROPPING PROTECTION / DIGITAL NETWORKS

 

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