The Design Of A Carrier-free Steganography Method Based On The Chinese Pinyin Scheme

Coverless information hiding technology refers to use large network data to construct carrier corpus,and then select the appropriate carrier from the carrier corpus or generate the carrier based on the carrier corpus.This technology does not need any modification to the carrier,and has good concealment and security.The existing text steganography methods are mainly divided into three categories.Modified steganography methods are easy to be attacked by machine detection;selected steganography methods are difficult to retrieve carrier;and coverless steganography methods often require multiple carrier,resulting in poor security.To solve the above problems,this thesis proposes two coverless steganography methods,which only needs one carrier and does not modify the carrier,and improves the retrieval efficiency of carrier by inverting index files.The main contents and innovations of this thesis can be summarized as follows:(1)Searchable corpus of carrier: Firstly,the data collection is carried out.This process can realize real-time data crawler of news webpage by means of web crawler technology,and achieve real-time updating of carrier.With news text as corpus and ES open source technology,creating an inverted index file for this news text in corpus,a searchable carrier corpus is realized.(2)Coverless text steganography method based on Chinese Pinyin : Firstly,preprocessing the syllable and tone of carrier and secret message based on shared dictionary,and establishing the syllable frequency table based on the statistical information of syllable frequency of carrier,and constructing the syllable and tone ordered sequence of secret message.In addition,based on the linear congruence algorithm,transforming the ordered sequence into two seed numbers as the transmission key,and the receiver extracts the secret message using the carrier text and the key.(3)Coverless text steganography based on tone flatness: With the help of N-Gram model,the feature statistical analysis of tone flatness can be carried out.The experimental analysis shows that Tri-Gram model is the best scheme for tone flatness of carrier text.The location label of the mapping relationship between carrier and secret message is designed.It is easier for sender and receiver to hide and extract information.The experimental results show that the searchable corpus improves the retrieval efficiency of text carriers.The two steganography methods realize the steganography process of single text carriers without any modification to the text carriers,and have high security.In addition,the steganographic capacity is nearly 30 times higher than the same type of method.