中文摘要：

隐蔽信道既是隐蔽通信的重要工具，也是黑客窃取信息的重要手段。鉴于微博已成为最流行的互联网应用之一，研究了基于微博发表时间的隐蔽信道模型。发送方把秘密信息编码为微博的发表时间，接收方获取发表时间并解码原信息，实现隐蔽通信。针对微博发表时间的三个典型特性，设计了四种编码方法，并对其信道容量和抗时延抖动能力进行了分析评价。结果表明，以时间间隔和条数特性组合的编码方法的性能最优。

英文摘要：

Covert channel is not only an important tool for concealment communication, but also an important means for hack- ers to transmit the stolen information. Since micro-blog became one of the most popular Internet applications, this paper inves- tigated a covert channel based on micro-blog posting time. The poster mapped secret information into the micro-blog posting time, and recovered the original information from the posting time. It proposed four encoding methods based on three typical characteristics of micro-blog posting time. Analyses show that the encoding method which combines the time interval and the number of micro-blog achieves best performance.