The purpose of the covert communication scheme is to conceal the communication behavior entirely.In such schemes,the sender and receiver rely on secret keys to establish a covert channel.However,conventional key excha...The purpose of the covert communication scheme is to conceal the communication behavior entirely.In such schemes,the sender and receiver rely on secret keys to establish a covert channel.However,conventional key exchange protocols would expose the key exchange process between them.An adversary who observes the key exchange would be aware of the existence of communication behavior.The keys used in covert communication are not suitable to be generated through conventional key exchange schemes.To address this,we propose a blockchain-based covert elliptic-curve Diffie-Hellman key exchange scheme(BCDH)to conceal the process of the key exchange in blockchain transactions.Following a straightforward setup,BCDH allows the sender and receiver to covertly exchange a secret key on a blockchain without direct communication.Furthermore,we expand the BCDH approach to operate across multiple blockchains,further enhancing its covertness and stability.We analyze BCDH from several perspectives,including covertness,security,randomness,etc.Additionally,we implement a prototype of BCDH on the Ethereum platform to assess its feasibility and performance.Our evaluation demonstrates that BCDH is efficient and well-suited for real-world applications.展开更多
Steganography based on bits-modification of speech frames is a kind of commonly used method, which targets at RTP payloads and offers covert communications over voice-over-IP(Vo IP). However, direct modification on fr...Steganography based on bits-modification of speech frames is a kind of commonly used method, which targets at RTP payloads and offers covert communications over voice-over-IP(Vo IP). However, direct modification on frames is often independent of the inherent speech features, which may lead to great degradation of speech quality. A novel frame-bitrate-change based steganography is proposed in this work, which discovers a novel covert channel for Vo IP and introduces less distortion. This method exploits the feature of multi-rate speech codecs that the practical bitrate of speech frame is identified only by speech decoder at receiving end. Based on this characteristic, two steganography strategies called bitrate downgrading(BD) and bitrate switching(BS)are provided. The first strategy substitutes high bit-rate speech frames with lower ones to embed secret message, which introduces very low distortion in practice, and much less than other bits-modification based methods with the same embedding capacity. The second one encodes secret message bits into different types of speech frames, which is an alternative choice for supplement. The two strategies are implemented and tested on our covert communication system Steg Vo IP. The experiment results show that our proposed method is effective and fulfills the real-time requirement of Vo IP communication.展开更多
文摘The purpose of the covert communication scheme is to conceal the communication behavior entirely.In such schemes,the sender and receiver rely on secret keys to establish a covert channel.However,conventional key exchange protocols would expose the key exchange process between them.An adversary who observes the key exchange would be aware of the existence of communication behavior.The keys used in covert communication are not suitable to be generated through conventional key exchange schemes.To address this,we propose a blockchain-based covert elliptic-curve Diffie-Hellman key exchange scheme(BCDH)to conceal the process of the key exchange in blockchain transactions.Following a straightforward setup,BCDH allows the sender and receiver to covertly exchange a secret key on a blockchain without direct communication.Furthermore,we expand the BCDH approach to operate across multiple blockchains,further enhancing its covertness and stability.We analyze BCDH from several perspectives,including covertness,security,randomness,etc.Additionally,we implement a prototype of BCDH on the Ethereum platform to assess its feasibility and performance.Our evaluation demonstrates that BCDH is efficient and well-suited for real-world applications.
基金Project(2011CB302305)supported by National Basic Research Program(973 Program)of ChinaProjects(61232004,61302094)supported by National Natural Science Foundation of China+2 种基金Project(ZQN-PY115)supported by Promotion Program for Young and Middle-aged Teacher in Science and Technology Research of Huaqiao University,ChinaProject(JA13012)supported by Education Science Research Program for Young and Middle-aged Teacher of Fujian Province of ChinaProject(2014J01238)supported by Natural Science Foundation of Fujian Province of China
文摘Steganography based on bits-modification of speech frames is a kind of commonly used method, which targets at RTP payloads and offers covert communications over voice-over-IP(Vo IP). However, direct modification on frames is often independent of the inherent speech features, which may lead to great degradation of speech quality. A novel frame-bitrate-change based steganography is proposed in this work, which discovers a novel covert channel for Vo IP and introduces less distortion. This method exploits the feature of multi-rate speech codecs that the practical bitrate of speech frame is identified only by speech decoder at receiving end. Based on this characteristic, two steganography strategies called bitrate downgrading(BD) and bitrate switching(BS)are provided. The first strategy substitutes high bit-rate speech frames with lower ones to embed secret message, which introduces very low distortion in practice, and much less than other bits-modification based methods with the same embedding capacity. The second one encodes secret message bits into different types of speech frames, which is an alternative choice for supplement. The two strategies are implemented and tested on our covert communication system Steg Vo IP. The experiment results show that our proposed method is effective and fulfills the real-time requirement of Vo IP communication.
