Abstract: Network steganography is a technology of covert communication which uses network data to transmit hidden message. In recent year, the focus of network steganography research is transforming from feasibility to improve concealment. The steganography based on multipath encoding is proposed by this background, At present, there is no effective method detecting this new steganography. The steganalysis method of multipath encoding is analyzed firstly, and then the steganalysis method based on conditional entropy is proposed through the analysis of normal multipath data. The experimental results show that this proposed method can detect this steganography with satisfied result when the detection windows size equal 1 200.

Key words: multipath, network steganography, conditional entropy, steganalysis

摘要： 网络隐写是一种以计算机网络通信数据为载体的隐蔽通信技术。近年来，研究人员对网络隐写的研究重点由原来的注重隐写可实施性向尽量提高隐写隐蔽性转变，基于多链路到达序列编码的隐写即在此背景下提出，目前尚无有效的检测算法。基于此，分析了基于多链路到达序列编码的隐写方法，然后通过对正常多链路数据流的建模分析，提出了基于条件熵的隐写分析方法。实验结果表明，所提方法在观测窗口达到1 200个数据包时对该隐写具有较好的检测效果。

关键词: 多链路, 网络隐写, 条件熵, 隐写分析