Research On Steganography Based On Instant Messaging

With the rapid development of Internet and communication technology,the Instant Messaging tools are essential in people's daily life.However,the network security problem has become more and more severe.People have to consider the problem of information security while enjoying the advantages of instant communication.The security of transmitting the chatting records related to national economic information,national military information,trade secrets or personal privacy has been obtained increasing attentions.Steganography,as a significant means for covert communication,is that secret information is embedded into cover data and transmitted to a receiver through public channel.When the receiver gets the stego-message,extracts the secret information.By this way,secret information is embedded into cover data imperceptibly.From the cover data,it is hard for attackers to detect the existence of confidential information.Therefore,steganography based on instant messaging is very necessary.In this paper,two novel steganography methods are proposed based on the text and voice in Instant Messaging.The proposed text steganography method is based on emoticons and interjections in chat.In this method,emoticons and interjections which are commonly used in Instant Messaging tools are used to embed secret information,therefore the imperceptibility of this method is very good.In sending and receiving parts,the same emoticon and interjection sets are established based on the meaning.Then through selecting the emoticons and interjections of corresponding encoding in different locations,secret information can be embedded into the chat text.The pre-shared sets of emoticons and interjections can be enlarged as required,so the embedding capacity and efficiency can be increased.Based on the method,a covert transmission system based on instant messaging is developed.The system is based on P2 P transmission and consists of two functions: general communication and cover communication.For voice chat,an adaptive steganography combining intervals with the variable low bit coding is proposed.The intervals for embedding secret messages into audio file and the thresholds in variable low bit coding are used for selecting the embedding location and embedding bits adaptively.The embedding capacity and efficiency are associated with the thresholds,thus they are variable.Experiment results demonstrate that the proposed method has good performance in terms of embedding efficiency and imperceptibility.