Research On Blockchain Covert Communication Method Based On Bitcoin Networ

The traditional covert channel usually uses the protocol data unit of the network protocol to hide the secret information.It is a static and single communication mode,which cannot guarantee the concealment,reliability and anonymity.Blockchain,as an emerging distributed technology,has attracted a lot of attention.Its transaction flooding broadcast,node dispersion,user anonymity and data security provide natural conditions for covert communication.At the same time,blockchain’s data transparency,low throughput,and large transaction characteristics also bring challenges to the construction of covert channels.At present,the research on blockchain based covert communication has been able to build a reliable covert channel.However,difficult transaction screening,reuse of transaction address and unguaranteed transaction order in the storage covert channel,and the low transmission efficiency in the time covert channel all become bottlenecks restricting its development and need to be solved urgently.To solve the above problems,based on traditional network covert communication technology and combined with the characteristics of blockchain,this paper designs two feasible blockchain network covert communication methods,including:(1)Aiming at the problems of time-type covert channel in the blockchain environment,a hybrid blockchain network covert communication method based on transaction construction and forwarding mechanism is proposed.In this method,both parties of covert communication first use the connection mechanism of the underlying node of Bitcoin to become the neighbor node,and then the sender uses the construction mechanism of Bitcoin transaction to create an invalid transaction,and embeds the secret information into it.Finally,the sender uses the broadcast mechanism of Bitcoin transaction to send the invalid transaction with secret to the receiver.In each covert communication,the invalid transaction with encryption sent by the sender is only propagated between its neighbor nodes.Nodes other than the covert communication receiver will discard the transaction immediately after verifying that the transaction is invalid.Therefore,the confidential transaction will not be permanently stored in the blockchain ledger.The experimental results show that the transmissioncapacity of this method is not only higher than the existing storage methods,but also the single communication time of covert communication is reduced to 2.5 seconds.(2)Aiming at the problems such as difficult transaction screening,transaction address reuse and unguaranteed transaction order in storage covert channel,a storage based blockchain covert communication method based on dynamic tag and chain transaction is proposed.In this method,the two communication parties first negotiate the key,and the sender embeds the secret information into the redundant fields of P-Q multi-signature transaction to generate the secret transaction.The design algorithm updates the public key and address of each secret transaction combined with the negotiation key to form the dynamic label and secret transaction chain,which solves the problem of address reuse when using static label.It also simplifies the transaction screening process of the recipient of covert communication.The experimental results and analysis show that the proposed method can resist various detection methods of attackers,and has high robustness and concealment.The concealment capacity is 60% higher than that of the existing storage method.