Text coverless information hiding based on compound and selection of words

In recent years, many researchers focus on the coverless information hiding because it realizes secret communication without modification by retrieving carriers including secret information (SI). However, the design of a coverless information hiding algorithm is very difficult, which mainly involves three aspects: (1) How to promote the efficiency of retrieving under the big data environment? (2) How to extract the SI in the received natural texts? (3) How to improve the hiding capacity (HC)? This paper proposes a novel text coverless information hiding algorithm based on the compound and selection of words, in which the reverse index is created to promote the efficiency of retrieving firstly. Then, Chinese characters are converted into binary numbers, which will serve as the location tags to determine the position of SI in the texts. Finally, combine the frequently used words and improve the HC according to the frequencies. The experimental results show that the proposed algorithm has a significant improvement in HC compared to the existing text coverless information hiding algorithms. In addition, the efficiency and security of the proposed algorithm are also proved.