Research On Blockchain-based Covert Communication Technology

With the rapid development of the information society,the problem of information leakage is becoming more and more serious.People put forward higher and higher requirements for the safe transmission of secret information.As one of the important technologies to protect the security of secret information transmission,covert communication is a technology to hide secret information in redundant data of public media,such as text,image,and video,and then construct covert channels for transmission in open channels without being discovered by attackers.The traditional network covert channel is most commonly used in covert communication,but the traditional covert channel has many defects and the detection technology is increasingly mature.Blockchain technology,with its advantages of decentralization,anonymity,and tamper-proof,has gradually become a new choice to build covert channels.Blockchain covert communication has become the focus of research in the field of covert communication in recent years.However,the existing schemes have the following shortcomings:(1)The schemes that simply use transaction fields have exposure risks;(2)The privacy of the sender and receiver cannot be truly guaranteed;(3)The transmission efficiency is low.In view of the above problems,this thesis has carried out in-depth research on covert communication,blockchain technology,and existing schemes.On this basis,two different blockchain covert communication schemes have been designed to solve the shortcomings of existing schemes and can safely use blockchain networks for covert communication.The main work of this thesis is as follows:(1)A covert communication scheme based on normal transaction concealment is designed.The transmission of secret information can be realized without embedding any information into the transaction.Experiments in the Bitcoin system show that the scheme improves the concealment of covert communication and has better transmission efficiency.(2)A coverless covert communication scheme based on word-frequency text generation is designed.By constructing a word-frequency codebase,the encrypted text is constructed according to the secret message by retrieval method,and the sender’s identity is hidden by using the ring signature algorithm.The receiver extracts the encrypted text and retrieves the secret information from the codebase to complete the covert communication.The experiment is completed in the Ethereum system,and the scheme has high concealment,concealment capacity,and efficiency.