Covert Communication Method Research Articles

A Blockchain-Based Secure Covert Communication Method via Shamir Threshold and STC Mapping

A Blockchain-Based Secure Covert Communication Method via Shamir Threshold and STC Mapping

Research on satellite overlapping covert communication method combined with CA

Abstract As electronic detection technology advances and the need for secure communication in terminal devices grows, traditional methods such as spread spectrum and overlapping communication are becoming inadequate for covert satellite communication. This paper introduces an enhanced approach by integrating the CA security protocol with satellite overlapping clandestine communication techniques. A network protocol stack, based on the TCP/IP reference model, is developed with a focus on the network layer and the data link layer. This study leverages the CSMA/CA key access technology at the link layer and proposes a method to mitigate interference in overlapping communication. It employs the LSTM algorithm to hypothesize the spectral posture of covert signals. It utilizes the least fitting degree method to minimize the impact of cover signals on the sub-spectrum of covert signals. The efficacy of this approach is assessed through simulation experiments, which provide a statistical analysis of the generated satellite overlapping covert signals. The results demonstrate a high anti-jamming probability, with complex envelope amplitude values ranging from 0.5 to 1.0, nearing a likelihood of 1. Additionally, the covert signals maintain a noise power spectral density similarity in the −2 to 2 Hz range, thereby enhancing their camouflaging effect.

A Covert Communication Method Adapted to Social Media Based on Time Modulation of Bullet Comments

A Covert Communication Method Adapted to Social Media Based on Time Modulation of Bullet Comments

HTTP Cookie Covert Channel Detection Based on Session Flow Interaction Features

HTTP cookie covert channel is a covert communication method that encodes malicious information in cookie fields to escape regulatory audits. It is difficult to detect this kind of covert channel according to the cookie content because cookie fields are mainly encoded in custom modes. To effectively identify the HTTP cookie covert channel, this paper proposes a detection method based on the interaction features of the session flow. First, we split the HTTP session flow into fine-grained “interaction process” subflows to comprehensively describe the communication process of the cookie. Then, we compare and analyze the differences between HTTP cookie covert channels and normal cookie communications based on the interaction process, design three types of 7-dimensional features, and build the detection model combined with the machine learning algorithm. Experimental results show that our method can effectively detect HTTP cookie covert channels, and the detection rate can reach 99%. We also prove that our method has advantages in stability and time performance compared with the existing detection methods through experiment and analysis. In addition, our method has certain practicability in the simulation environment with imbalanced data.

A Derivative Matrix-Based Covert Communication Method in Blockchain

The data in the blockchain cannot be tampered with and the users are anonymous, which enables the blockchain to be a natural carrier for covert communication. However, the existing methods of covert communication in blockchain suffer from the predefined channel structure, the capacity of a single transaction is not high, and the fixed transaction behaviors will lower the concealment of the communication channel. Therefore, this paper proposes a derivation matrix-based covert communication method in blockchain. It uses dual-key to derive two types of blockchain addresses and then constructs an address matrix by dividing addresses into multiple layers to make full use of the redundancy of addresses. Subsequently, to solve the problem of the lack of concealment caused by the fixed transaction behaviors, divide the rectangular matrix into square blocks with overlapping regions and then encrypt different blocks sequentially to make the transaction behaviors of the channel addresses match better with those of the real addresses. Further, the linear congruence algorithm is used to generate random sequence, which provides a random order for blocks encryption, and thus enhances the security of the encryption algorithm. Experimental results show that this method can effectively reduce the abnormal transaction behaviors of addresses while ensuring the channel transmission efficiency.

A covert communication method based on imitating bird calls

A covert communication method based on imitating bird calls

A Group Covert Communication Method of Digital Currency Based on Blockchain Technology

With the rapid development of the Internet, it has become a hot spot in protecting important information from illegal theft and destruction during network transmission. The characteristics of strong robustness, anonymity and distributed transmission in blockchain technology can precisely make up for the disadvantages faced by traditional covert communication in transmitting important data, such as poor robustness, easy exposure of participants and difficulty in achieving group covert transmission. Therefore, a group steganography method for digital currency based on blockchain technology is proposed in this paper. In this method, an index matrix of address interaction is designed for group covert communication, using the address interaction relationship and transaction amount to hide secret message alternately, the transaction hiding secret message is published on the blockchain. In different groups, the receivers use different keys to extract different secret message. The method proposed also introduces a fine-grained group division mechanism to control the spread of secret information and reduce the risk of secret information leakage. And the application scenarios of the method proposed are more universal, breaking the limitation of using a single digital currency for covert communication on the blockchain. In addition, the proposed method modulates the number of addresses reasonably by sensing the generation time of the block, enhancing the concealment of the method. Through practical tests on a variety of mainstream digital currencies, the experimental results show that digital currencies with smaller block generation times need to consume less embedding time.

Covert Communication for Wireless Networks with Full-Duplex Multiantenna Relay

In this work, we investigated a covert communication method in wireless networks, which is realized by multiantenna full-duplex single relay. In the first stage, the source node sends covert messages to the relay, and the relay uses a single antenna to send interference signals to the adversary node to protect the covert information being transmitted. In the second stage, the relay decodes and forwards the covert information received in the first stage; at the same time, the relay uses zero-forcing beamforming to send interference signals to the warden to ensure covert transmission. The detection error rate, transmission outage probability, maximum effective covert rate, and other performance indicators are derived in two stages, and the total performance of the system is derived and analyzed. Then, the performance indicators are verified and analyzed by simulation. Our analysis shows that the maximum effective covert rate of using the characteristics of multiantenna to interfere with Willie in the second stage is taken as the total covert performance of the system, and the transmission interruption probability is significantly less than that of the first stage, so the corresponding maximum effective concealment efficiency will be greater.

Bionic covert underwater communication focusing on the overlapping of whistles and clicks generated by different cetacean individuals

Bionic camouflage covert underwater acoustic communication technology is playing an increasingly important role in the covert transmission of underwater information. Most cetaceans are group-living animals, and multiple cetaceans often appear in a specific ocean area at the same time. As a result, different cetacean individuals may generate whistles and clicks simultaneously, and the overlapping of whistles and clicks often appears in the received sound signals. Focusing on the overlapping characteristic of cetacean calls, this paper designs a bionic camouflage covert underwater acoustic communication method to improve the covertness and communication rate. The combined encoding through whistles and clicks overlapping of different cetacean individuals makes the constructed communication signals more in line with the characteristics of original cetacean calls, which improves the communication covertness. The pulse-to-pulse correlation and time delay difference encoding based on whistles and clicks are combined to improve the communication rate. Furthermore, the whistle signal processing algorithm based on time–frequency spectrogram image and morphology processing is utilized to separate the whistles and clicks in the received signals. And the whistle and click sequence are decoded, respectively. Finally, the bit error rates of the combined communication sequence, whistle sequence and click sequence are compared by conducting simulations. And the effectiveness, reliability and covertness of the proposed covert communication method are demonstrated through the simulations.

Biomimicking Covert Communication by Time-Frequency Shift Modulation for Increasing Mimicking and BER Performances.

Underwater acoustic (UWA) biomimicking communications have been developed for covert communications. For the UWA covert communications, it is difficult to achieve the bit error rate (BER) and the degree of mimic (DoM) performances at the same time. This paper proposes a biomimicking covert communication method to increase both BER and DoM (degree of mimic) performances based on the Time Frequency Shift Keying (TFSK). To increase DoM and BER performances, the orthogonality requirements of the time- and frequency-shifting units of the TFSK are theoretically derived, and the whistles are multiplied by the sequence with a large correlation. Two-step DoM assessments are also developed for the long-term whistle signals. Computer simulations and practical lake and ocean experiments demonstrate that the proposed method increases the DoM by 35% and attains a zero BER at −6 dB of Signal to Noise Ratio (SNR).

A Time-Based Dynamic Operation Model for Webpage Steganography Methods

The webpage steganography technique has been used for a covert communication method for various purposes in which a sender embeds a secret message into a plain webpage file like an HTML file by using various steganography methods. With human eyes, it is very difficult to distinguish between the original webpage (cover webpage) and the modified webpage with the secret data (stego webpage) because both are displayed alike in a web browser. In this approach, when two communicating entities want to share a secret message, a sender uploads a stego webpage to a web server or modifies an existing webpage in the web server by using a webpage steganography method, and then a receiver accesses the stego webpage to download and extract the embedded secret data from it. Meanwhile, according to our extensive survey, we observed that most webpage steganography methods focused on proposing or improving steganography algorithms but did not well address how to operate a stego webpage as time passes. However, if a stego webpage is used in a static way such that the stego webpage does not change and is constantly exposed to web clients until the sender removes it, such a static operation approach will limit or badly affect the hiding capacity and undetectability of a webpage steganography method. By this motivation, in this paper, we proposed a time-based dynamic operation model (TDOM) that improves the performance of existing webpage steganography methods in terms of hiding capacity and undetectability by dynamically replacing the stego webpage with other stego webpages or the original webpage. In addition, we designed two time-based dynamic operation algorithms (TDOA-C and TDOA-U), which improve the hiding capacity of existing methods and TDOA-U for improving the undetectability of existing methods, respectively. To validate our model and show the performance of our proposed algorithms, we conducted extensive comparative experiments and numerical analysis by implementing two webpage steganography methods with our TDOM (CCL with TDOA-C and COA with TDOA-C) and tested them in the web environment. According to our experiments and analysis, our proposed algorithms could significantly improve the hiding capacity and undetectability of two existing webpage steganography methods.

Covert underwater communication based on combined encoding of diverse time-frequency characteristics of sperm whale clicks

Bio-inspired camouflage covert underwater acoustic communication has been studied widely recently. In order to improve the camouflage ability and communication rate, a bio-inspired covert underwater acoustic communication method based on combined encoding of diverse time–frequency characteristics of sperm whale clicks is proposed. The characteristics of time–frequency contour shapes and frequency-band distributions are classified and counted, and the communication codes are constructed based on the two characteristics. According to the inter-click interval characteristic of sperm whale click pulse trains, the bionic communication sequences are constructed through differential time delay difference encoding between different communication codes. Based on the proposed combined encoding method of diverse time–frequency characteristics, the constructed communication sequence contains a large number of different modulated clicks. It conforms to the characteristic that there exists a large number of and a variety of clicks in the true click pulse train, which improves the camouflage ability. The true sperm whale click pulses are inserted into the communication sequences as camouflage pulses to further improve the camouflage ability. Furthermore, the communication rate is improved due to using multiple characteristics to represent different encoding information in the proposed method. Simulations are implemented to demonstrate the effectiveness, reliability and covertness of the proposed covert communication method.

A Covert Communication Method Using Special Bitcoin Addresses Generated by Vanitygen

A Covert Communication Method Using Special Bitcoin Addresses Generated by Vanitygen

Camouflage Covert Communication in Air by Imitating Cricket’s Sound

When the radio communication of an armed squad fighting in a jungle is interfered with by enemy's radio jamming equipment and their command and intelligence cannot be transmitted and exchanged, are there any other communication methods that can be used to solve such an emergency and covert communication problem? Focusing on this problem, a camouflage covert communication method (CCCM) in air is proposed by imitating cricket's sound. As well-known, there exist all kinds of animals' sounds in the jungle; however, hearing these animals' sounds, people generally considers them as background noise and ignores them. Based on this fact, the proposed CCCM uses the cricket's sound as the carrier wave, imitates the features of the cricket's call sequence to construct the camouflage communication sequence, and utilizes the time interval (TI) between two adjacent pulses to encode information. Meanwhile, other animals' sound is superimposed to the camouflage communication sequence to improve the camouflage ability of the generated communication sequence. Experimental results are provided to demonstrate the performance of the proposed CCCM.

Reversible Data Hiding in Digital Image

The growth of multimedia technologies and the attractiveness of internet are dramatically increasing. All kinds of multimedia information like audio, video and images can be obtained freely and copied even edited then transmitted as one wishes. At the same time, this makes the integrity, reliability, and security of data transmitted under threat. The information security has always been a major concern. As one of the ways to solve the security problem is data hiding technology that embeds the secret data imperceptibly into the cover media by slightly modifying some of the cover elements. This paper discusses the basic principle s of reversible data hiding (RDH) as a method of covert communication in order to understand how information is embedded in the graphical representation and covers the in-depth discussion on image compression.

Imperceptible Steganography Scheme with High Payload Capacity using Genetic Algorithm and Particle Swarm Optimization

Security is the most significant parameter in all type of confidential data transfers. Steganography is used to enhance the security of such confidential communications. Steganography is a method of covert communication in which the existence of secrecy is concealed. In image steganography, achieving high data embedding capacity and simultaneously retaining good visual quality is a very tricky and difficult objective. In this paper, a reversible, secure, extremely imperceptible and high payload capacity steganography technique in the spatial domain is proposed. The proposed method employs evolutionary computation techniques to identify the most optimum locations and arrangements for secret data embedding. The proposed technique uses Particle Swarm Optimization to find the best possible order of data hiding whereas Genetic algorithm is used to identify the best possible arrangements to modify secret data to produce least amount of change in cover-image. The result of the proposed scheme is compared with many steganography techniques and the proposed scheme outperforms the existing schemes in terms of imperceptibility. The proposed technique produces an average PSNR value of 46.40 dB at 2 bit per pixel data embedding rate.

Detection of TCP covert channel based on Markov model

Network covert channel is a covert communication method by hiding covert messages into overt network packets. In recent years, with the development of various hiding methods, network covert channel has become a new kind of threat for network security. The covert channel that uses the redundancies existing in TCP protocol to make hiding is called TCP covert channel. In this paper, the behaviors of TCP flows are modeled by the Markov chain composed of the states of TCP packets. And the abnormality caused by TCP covert channel is described by the difference between the overt and covert TCP transition probability matrix. The detection method based on MAP is proposed to detect the covert communication hidden in TCP flows under various applications such as HTTP, FTP, TELNET, SSH and SMTP. Experiments show that the proposed algorithm achieves better detection performance than the existing methods.

A Novel Covert Communication Method Based on WCDMA

Covert communication can effectively improve the security of communication content, which has been widely used in wireless communication systems. Most approaches for covert communication are based on the principle of text-embedded in upper layer of the OSI model. In this paper, a novel covert communication scheme is proposed. This method takes advantage of scramble codes and message processing rules of the WCDMA system. It uses a downlink scramble code in the normal WCDMA uplink signal, so that the covert messages will not be received by the base station (BS) and the user equipment (UE). Simulation result shows that the proposed covert communication method has a low bit error rate (BER) performance, and will only make the signals of different business to a slightly lower data transmission rate.

A covert communication method via spreadsheets by secret sharing with a self-authentication capability

A new covert communication method with a self-authentication capability for secret data hiding in spreadsheets using the information sharing technique is proposed. At the sender site, a secret message is transformed into shares by Shamir's (k, n)-threshold secret sharing scheme with n=k+1, and the generated k+1 shares are embedded into the number items in a spreadsheet as if they are part of the spreadsheet content. And at the receiver site, every k shares among the k+1 ones then are extracted from the stego-spreadsheet to recover k+1 copies of the secret, and the consistency of the k+1 copies in value is checked to determine whether the embedded shares are intact or not, achieving a new type of blind self-authentication of the embedded secret. By dividing the secret message into segments and applying to each segment the secret sharing scheme, the integrity and fidelity of the hidden secret message can be verified, achieving a covert communication process with the double functions of information hiding and self-authentication. Experimental results and discussions on data embedding capacity, authentication precision, and steganalysis issues are also included to show the feasibility of the proposed method.

A Novel Digital Image Covert Communication Scheme Based on Generalized FCM in DCT Domain

A novel covert communication method of digital image is presented, based on generalized fuzzy c-means clustering (GFCM), human visual system (HVS) and discrete cosine transform (DCT). Therefore, the original image blocks are classified into two classes according to specified characteristic parameters. So one block is suited for embedding security information, but the other block is not. Hence the appropriate blocks can be selected in an image to embed the security information by selectively modifying the middle-frequency part of the original image in conjunction with HVS and DCT. Furthermore the maximal information strength is fixed based to the frequency masking. Also to improve performances of the proposed algorithm, the security information is modulated into the chaotic modulation array. The simulation results show that we can remarkably extract the hiding security information and can achieve good robustness with common signal distortion or geometric distortion and the quality of the embedded image is guaranteed.