Audio digital steganography and extraction method in compressed domain based on index values

The invention discloses an audio digital steganography and extraction method in a compressed domain based on index values. A steganography operation of the digital steganography method is carried out in the processes of quantization and entropy encoding, so distortion caused by steganography can be controlled effectively with the help of a distortion adjustment mechanism, therefore, steganography safety of secret information is guaranteed effectively, and undetectability and transparency of the secret information are guaranteed. By means of the audio digital extraction method, bits of the secret information are extracted directly through index values of audio particles, and the extraction process is simple and effective. Due to the fact that the index values of the audio particles can be extracted from side information of the audio particles, the audio particles need not to be decoded, namely, such complex procedures as anti-entropy decoding, inverse quantization, inverse modified discrete cosine transform (MDCT) and inverse filtering, and thus timeliness of secret information extraction is improved effectively and computation complexity is reduced greatly.