Abstract
In order to protect user privacy or guarantee free access to the Internet, the network covert channel has become a hot research topic. It refers to an information channel in which the messages are covertly transmitted under the network environment. In recent years, many new construction schemes of network covert channels are proposed. But at the same time, network covert channel has also received the attention of censors, leading to many attacks. The network covert channel refers to an information channel in which the messages are covertly transmitted under the network environment. Many users exploit the network covert channel to protect privacy or guarantee free access to the Internet. Previous construction schemes of the network covert channel are based on information steganography, which can be divided into CTCs and CSCs. In recent years, there are some covert channels constructed by changing the transmission network architecture. On the other side, some research work promises that the characteristics of emerging network may better fit the construction of the network covert channel. In addition, the covert channel can also be constructed by changing the transmission network architecture. The proxy and anonymity communication technology implement this construction scheme. In this paper, we divide the key technologies for constructing network covert channels into two aspects: communication content level (based on information steganography) and transmission network level (based on proxy and anonymity communication technology). We give an comprehensively summary about covert channels at each level. We also introduce work for the three new types of network covert channels (covert channels based on streaming media, covert channels based on blockchain, and covert channels based on IPv6). In addition, we present the attacks against the network covert channel, including elimination, limitation, and detection. Finally, the challenge and future research trend in this field are discussed.
Highlights
With the rapid development of information technology, Internet has penetrated into every aspect of people’s lives
Many researches show that the use of network covert channel can protect user privacy and guarantee users’ right to free access to Internet [6,7,8]. e secure transmission of secret messages in the communication process refers to two aspects: one is the communication content security [9] and the other is the communication connection security [6, 10, 11]
With the development of emerging networks, many network covert channels in the new network environment have been proposed. e covert channels based on streaming media network hide secret messages in audio and video traffic and use popular streaming media applications as the carrier
Summary
In order to protect user privacy or guarantee free access to the Internet, the network covert channel has become a hot research topic. It refers to an information channel in which the messages are covertly transmitted under the network environment. Many new construction schemes of network covert channels are proposed. Many users exploit the network covert channel to protect privacy or guarantee free access to the Internet. We divide the key technologies for constructing network covert channels into two aspects: communication content level (based on information steganography) and transmission network level (based on proxy and anonymity communication technology). The challenge and future research trend in this field are discussed
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