Huffman table swapping-based steganograpy for MP3 audio

Raw audios contain significant amount of redundancy which can be used for steganographic purposes. But practically most audios are stored and transmitted in the compressed formats. In this paper, we present a MPEG-1 Layer III (MP3) audio CODEC based steganographic method to embed secret message during encoding. The Huffman tables in MP3 standard are first partitioned into three groups. The secret message is then embedded by Huffman table swapping strategy. Instead of fully decoding the stego-audio, the extraction of the secret message can be done just by parsing the side information. The proposed method is designed under the restrictions of the MP3 compression standard without any modifications or additions to the existing standard. Experimental results show that the proposed method can provide much higher capacity than other approaches, while satisfying the low distortion and security requirements for steganography on MP3 audios.