Research On Covertly Exfiltrating Information From Air-Gapped Networks Using Display-Camera Devices

Air-gap,also called physical isolation,is widely used to protect high-security com-puter systems from external threats by disconnecting the Internet from the isolated net-work.How to transmit information from the air-gapped system has attracted many re-searchers,among which the screen-camera air-gapped covert channel has great research value.By analyzing the characteristics of human vision system,this paper studies two kinds of information covert transmission technology under air-gapped network,and combines secret sharing algorithm to study the information robust transmission technology.The main work of the paper is as follows:First,an information covert transmission technology based on hidden QR code is proposed.This technology chooses QR code as the encoding method of information and uses its strong error-correcting ability to improve the robustness of information transmis-sion.Compared with the existing method,which requires black and white background,this technology has stronger adaptability to carriers.Second,a covert transmission technique based on visual retention effect is proposed.This technology makes use of the phenomenon of visual fusion to the image perception under the condition of high-speed refresh of the screen image,conceals the information embedding behavior of the carrier image,and improves the concealment and transmission rate of the information transmission process.Third,this paper proposes an image secret sharing algorithm based on the Chinese remainder theorem,by sharing the high 7 bits and embedding the least bit into the ran-dom integer.The algorithm has the advantages of less parameters,no extra encryption and lossless recovery effect.Applied to the air-gapped network information transmission scenario,the algorithm slove the problem caused by the loss of data frames.