中文摘要：

隐蔽通道的存在给信息系统的保密性造成了严重威胁，其信息传递机理研究是实施隐蔽通道检测与控制的前提和基础．本文首先将安全系统解释成带有信号调制能力的通信信道，将信息传递过程类比成常规通信过程，研究了相应的通信要素（编码器、调制器、载波介质及解码器等）及其所对应的实体；基于这些通信要素和对应实体，提出了隐蔽通道的信息传递模型；在该模型和系统形式化描述的基础上，研究机密信息泄露的过程，并讨论了隐蔽通道的信道带宽计算方法．

英文摘要：

Covert channels cause serious security threat to information systems,and the research on the information transmission principle of the channels is crucial to detect and eliminate them. Covert channel is essentially a commtmication channel to transmit information illegally. In the paper, an information system is firstly regarded as a communication channel, and the information transmission in it is considered as a regular communication process. Then, an information transmission model is introduced, and it can present clearly the information transmission principle and the communication process including encoding, concocting and decoding. Lastly, a method of calculating the communication bandwidth is discussed.