| With the rapid advancement of science and technology,network security has become a focus that cannot be ignored in today’s society.However,there are some problems in the covert communication technology under the traditional network,such as the central node cannot be trusted,the information is easy to be modified,and the risk of secret information leakage.To solve these problems,blockchain technology has become an effective means due to its decentralization and non-tamperable characteristics.At present,the blockchain covert communication scheme has problems such as low communication efficiency,low embedding capacity,weak concealment and poor scalability,and the current covert communication scheme under the blockchain is mostly a theoretical model,lacking design in specific scenarios and A covert communication scheme in a multi-person scenario.Therefore,in response to these problems,this thesis conducts in-depth research on the covert communication of the blockchain,and designs a covert communication model under the blockchain.A covert communication model based on address pool and contract invocation designed,The model separates data transmission and communication control in covert communication through two smart contracts.Each covert communication can choose a different smart contract for data transmission,making The model is more flexible and has the ability to resist monitoring;the data transmission part embeds confidential information into multiple addresses through the address matching algorithm,and then aggregates the location information of the embedded fragments on the same address,and uses the aggregation result as the contract call initiated by the address Function parameters are hidden,thereby expanding the scope of address embedding and improving the efficiency of information embedding;the communication control part mainly transmits information such as the start flag,control,ciphertext length,ciphertext type,and address of concealed communication,and uses the function parameters called by the contract to hide the control Information,by saving hidden information with the help of contract calls,the receiver does not need to directly participate in the communication,thus effectively hiding the identity of the receiver.The experimental results show that,compared with the address-embedded covert communication model,this model has higher information embedding efficiency and lower address generation overhead.This thesis expands on the designed blockchain covert communication model,introduces the topic mechanism,and adds topic information at the beginning of the communication control information.Only users who subscribe to the topic can parse the transaction or forward it,so as to achieve multicast between covert channels Effect,and designed the address exchange method in the extension model and the covert communication method between contracts,so that the model can be flexibly extended according to different application requirements.The experimental results show that the extended model can establish a multi-person covert channel,complete one-to-many covert communication,and has higher transmission efficiency as the number of covert communication increases.Combined with the application scenario of confidential file transmission,this thesis uses the designed blockchain covert communication extension model to establish a covert channel,completes the transfer of confidential files between multiple people and the transmission of different types of files,and verifies the feasibility of the model designed in this thesis. |
