An Information Hiding Algorithm For G.729 Based On Positions And Amplitudes Of Nonzero Pulses

VoIP(Voice over Internet Protocol)is based on voice stream,which has the advantages of large data transmission and wide applications.But the VoIP system is confronted with the threats of data security and privacy leaks.With the idea of information hiding,the redundant information which is formed after speech compression coding is utilized to carry on information hiding process.The process is able to achieve the purpose of secure communication and guarantee the data security for sensitive information.The fact is pointed that the codebook search is non-traversal and there is redundancy on the basis of studying the structure of the fixed codebook in G.729 and the search method of optimal code word vector.Thus,the information hiding algorithm based on positions and amplitudes of nonzero pulses is proposed.In this algorithm,secret information is utilized to control the codebook search process.In the search process,the idea of least significant pulse replacement is used and information hiding is carried out by a functional relationship between the nonzero pulse position and secret information.Moreover,in view of the low efficiency of the existing CNV(Complementary Neighbor Vertex)information hiding algorithm,an improved CNV information hiding algorithm based on matrix coding is proposed.The efficiency of the improved algorithm is 33.5% higher than the previous algorithm.These two algorithms are simulated in the working environment and the experimental results show that the information hiding algorithm based on positions and amplitudes of nonzero pulses is able to ensure the invisibility and real-time property and more importantly,the hiding capacity is up to 400bit/s.The hiding efficiency of the improved algorithm based on matrix encoding reaches 2.67.