摘要：随着互联网通信技术的迅猛发展，信息交流变得更加快捷和便利，但同时信息安全问题变得更为严峻，因而迫切需要开发适应新形势的秘密通讯工具。信息隐藏技术是一种加密技术之外的较好的进行秘密信息传输的手段，而网络隐信道技术则是一种将秘密信息嵌入到网络数据流之中的信息隐藏技术。本文在时间式隐信道系统构建和隐信道系统检测相关理论的基础上，重点针对基于Skype时间序列模型的时间式隐信道系统进行了设计，并且使用了基于信息熵的检测算法来验证所设计隐信道系统的安全性。

本文首先对网络隐信道的概念、模型、分类以及隐信道相关技术做了简单介绍，并重点介绍了时间式隐信道系统的相关概念和理论。

针对基于模型的时间式隐信道系统方法的实现，具体完成工作如下：通过捕获Skype通信的正常数据，建立模型；对Skype通信的累积分布函数模型进行分析；对需要发送的隐秘信息进行扩频编码，以提高其不可检测性；将编码后的含密数据调制成符合Skype正常通信的包间时延；把调制后的隐秘信息通过网络发送给接收方，接收方对接收的含密数据进行解调、解码，最终得到发送方发送的隐秘信息。

设计并实现了基于信息熵的检测算法，以验证所设计隐信道的安全性，实验结果表明本文所设计的网络隐信道系统在安全性方面满足设计要求。

论文最后分析了本次设计中的不足之处，并对未来学习和工作进行了展望。

关键字：时间式隐信道，模型拟合，熵检测，Erlang分布

Abstract：With the rapid development of Internet communication technology, information exchange has become more efficient and convenient, but at the same time the information security problem becomes more serious, so the urgent need to develop a new situation to adapt to the secret communication tools. Information hiding technology is a kind of encryption technology outside the better means of secret information transmission, and network hidden channel technology is a secret information embedded in the network data flow information hiding technology. Based on the theory of time implicit channel system construction and hidden channel system detection, this paper focuses on the design of time-based hidden channel system based on Skype time series model, and uses the detection algorithm based on information entropy to verify the design hidden The security of the channel system.

In this paper, the concept, model, classification and related technologies of hidden channel are briefly introduced, and the related concepts and theories of time-type hidden channel system are introduced.

In order to realize the normal data of Skype communication, a model is established. The cumulative distribution function model of Skype communication is analyzed, and the secret information needed to be transmitted is spread and encoded. In order to improve its non-detectability; the encoded secret data is modulated into the packet communication delay in line with the normal communication of Skype; the modulated secret information is sent over the network to the receiver and the receiver demodulates the received encrypted data , Decoding, and ultimately get the sender to send the secret information.

The algorithm based on information entropy is designed and implemented to verify the security of the designed hidden channel. The experimental results show that the network hidden channel system designed in this paper satisfies the design requirements in terms of security.

Finally, this paper analyzes the shortcomings of this design and prospects the future study and work.

Keywords: Temporal implicit channel,Model fitting, Entropy detection, Erlang distribution

目 录

第一章绪论