Steganography in low bit-rate speech streams based on quantization index modulation controlled by keys

• Published in: Science China. Technological sciences 2017-10, Vol.60 (10), p.1585-1596
• Main Authors: Huang, YongFeng, Tao, HuaiZhou, Xiao, Bo, Chang, ChinChen
• Format: Article
• Language: English
• Subjects: Algorithms; Codec; Digital media; Engineering; G.723.1; IP (Internet Protocol); Measurement; Modulation; Partitions; Redundancy; Signal distortion; Speech; Steganography; VoIP; 低比特率; 控制算法; 索引; 语音编解码器; 调制; 量化器
• ISSN: 1674-7321; 1869-1900
• DOI: 10.1007/s11431-016-0707-3

Since low bit-rate speech codecs used for voice over internet protocol （VolP）, such as iLBC （internet low bit-rate codec）, G.723.1 and G.729A, have less redundancy due to high compression, it is more challenging to embed information in low bit-rate speech streams of VolP. In this study, a new method is proposed for steganography in low bit-rate speech streams of VolP. The core idea of this method is setting up a graph model for the codebook space of the quantizer. Based on the graph model, the method realises a quantization index modulation （QIM）-controlled algorithm for partitioning the codebook space. It can be proved that this method can minimize signal distortion while steganography taking place. Taking into account codeword partition balance and partition diversity, the proposed steganographic algorithm was based on QIM controlled by secret keys, i.e., mapping the ways of codebook division into secret keys, thereby significantly improving the undetectability and robustness of VolP steganography. Performance measurements and steganalysis experiments showed that the proposed QIM-controlled steganographic algorithm was more secure and robust than the QIM algorithm, the conventional RANDOM algorithm and the original codebook algorithm.