Audio steganography with less modification to the optimal matching CNV-QIM path with the minimal hamming distance expected value to a secret

To improve the imperceptibility without decreasing the steganographic capacity when steganography by a modification to an audio is carried out, this paper proposes an optimal matching path algorithm to reduce the modification to achieve it. A steganography operation unit is defined, which is composed of every N consecutive audio frames and each frame includes M LPC parameters. All these parameters in the same steganography operation unit will form an M × N matrix. A traversal path is a sequence of all these parameters in the matrix. Each parameter in the matrix will be converted into a one-bit binary digit based on two subcodebooks divided by the complementary neighbor vertex (CNV) method. Thus, every traversal path will have a corresponding binary string named PathBinStr. Steganography is performed by computing the Hamming distance between the binary secret and the corresponding PathBinStr and selecting the traversal path with minimal hamming distance expected value to hide the secret via the CNV embedding method. The experimental results show that the proposed steganography algorithm has better performance in audio quality and the modified bit rate decreases from 50 to 37.4% when only 6 traversal paths are predefined, and its processing time can satisfy the real-time requirement of VoIP services. Also, it does not change the audio size, and the theoretical analysis and experiments show its undetectability is good.