Dynamic matrix encoding strategy for voice-over-IP steganography

In order to optionally regulate embedding capacity and embedding transparency according to user's requirements in voice-over-IP(VoIP) steganography,a dynamic matrix encoding strategy(DMES) was presented.Differing from the traditional matrix encoding strategy,DMES dynamically chose the size of each message group in a given set of adoptable message sizes.The appearance possibilities of all adoptable sizes were set in accordance with the desired embedding performance(embedding rate or bit-change rate).Accordingly,a searching algorithm that could provide an optimal combination of appearance possibilities was proposed.Furthermore,the roulette wheel algorithm was employed to determine the size of each message group according to the optimal combination of appearance possibilities.The effectiveness of DMES was evaluated in StegVoIP,which is a typical covert communication system based on VoIP.The experimental results demonstrate that DMES can adjust embedding capacity and embedding transparency effectively and flexibly,and achieve the desired embedding performance in any case.For the desired embedding rate,the average errors are not more than 0.000 8,and the standard deviations are not more than 0.002 0;for the desired bit-change rate,the average errors are not more than 0.001 4,and the standard deviations are not more than 0.002 6.

QoE-driven voice quality evaluation model of VoIP based on network simulation

The quality of experience（ QoE） evaluation model for voice over IP（ VoI P） service is studied to analyze the impact of network parameters on voice quality and monitor voice quality in real-time for operators.Firstly,the influence of some network parameters on the voice quality of VoI P is investigated. Then,a simulation platform for VoI P transmission is built to collect voice data under different network enviornments. According to the simulation results,a new mapping model between these arguments and VoI P voice quality is deduced. Finally,the accuracy of this voice quality evaluation model is examined and the results demanstrate that it has high reliability and feasibility.

RESEARCH ON THE ALGORITHM FOR IDENTIFYING VOIP SESSION

In this letter,a novel algorithm is proposed for identification of one popular type of VoIP(Voice over IP) application,MSN VoIP,based on both behavior pattern and protocol characteristics.In addition,the experiment for validation is implemented.Since there exists no method identifying MSN VoIP session and furthermore the IP addresses,domain names,ports and even the protocols MSNP works over,are all alterable during the application,which makes it difficult to identify MSN VoIP session,this work will be helpful to advance the research on VoIP identification.

An Improved NID Steganography Method for Low Bitrate Speech on VoIP

In the procedure of encoding process on low bitrate speech,fixed codebook division is an efficient and promising embedding method for steganography.An improved neighbor index division(NID)steganography method based on the high bitrate frame of G.723.1 codec(6.3kbit/s)is proposed,which employs the parity and low distortion of neighbor indices for G.723.1 fixed codebooks.Differing from previously NID method which performs quantized index modulation(QIM)beforehand,the proposed method divides codeword indices into separate sub-codebooks according to the secret message bits dynamically in the original G.723.1 codec quantization period.Compared with existing NID method,our proposed method doesn’t need to divide the codebook before the encoding starts.The embedding and codebook dividing happen simultaneously,which utilizes the characteristics of specific secret message bits.The experiment results show that the proposed method has a much lower quality degradation for the decoding speech and still fulfills the low latency requirement for communication.