即时通信中的隐蔽通信模型及方法研究

项目名称： 即时通信中的隐蔽通信模型及方法研究

项目编号： No.U1536113

项目类型： 联合基金项目

立项/批准年度： 2016

项目学科： 管理科学

项目作者： 王开西

作者单位： 青岛大学

项目金额： 64万元

中文摘要： 即时通信系统拥有庞大的用户数，支持丰富的业务特征和媒体类型，使用多种通信协议，具有隐藏最佳载体的两个必备特征。但其中的短文本、高压缩的小图像、短语音或微视频等媒体存在隐写容量小、隐写难度大的问题。因此，提高隐写容量是基于即时通信系统进行隐写必须解决的关键问题。而隐写容量和隐蔽性往往相互制约，所以解决系统隐写容量的同时必须考虑其隐蔽性问题。针对这些问题，本项目首先从设计新算法、融合现有算法两种方式提高系统隐写容量：1）设计基于即时通信系统业务特征和通信协议的隐写算法；2）构建跨载体、高容量的多隐蔽信道分级统一隐写通信模型。其次，通过两种方法提高系统隐蔽性：1）定义和分类隐蔽信道隐蔽性等级，多隐蔽信道统一模型支持分级策略，对隐蔽消息分块元数据和消息块进行分级传输；2）自适配分块隐写算法，根据载体的统计分布特征对预处理后的隐蔽信息适配性分块、隐写传输。最后拟基于微信平台开发原型系统进行验证和分析。

中文关键词： 信息隐藏；即时通信；跨载体隐写；隐蔽通信；隐写模型

英文摘要： Instant Messaging (IM) systems have a large number of users, support a lot of service features and rich media types, and employ many kinds of communication protocols, which meet the two features that the best carriers for secret message must possess. But short messages, high compressed and small images or short audio or micro media are mainly exchanged in the IM systems, and they have a low steganographic capacity, and it is difficult to hide information in them. Therefore, how to increase the steganographic capacity is a must issue to be solved in an Instant Messaging services. At the same time, steganographic capacity and the quality of concealment are always restricted mutually, so the solution to raise the steganographic capacity must also be examined from the aspect of imperceptibility. To solve the steganography capacity issues, two approaches are employed: 1) Design new steganography algorithms based on the service features and communication protocols of the IM services; 2) Construct a multiple covert channel unified steganographic communication model with high capacity, which supports cross-over steganography; To improve the imperceptibility, two methods are proposed: 1) The definition and classification of the covert channels’ hidden levels are put forwards, and are supported by the unified steganographic communication model above to transport the meta-data message blocks and secret message blocks in different covert channel with different hidden level; 2) Adaptively splitting steganographic algorithm: a secrete message will be divided into the blocks according to the covert channels’ statistical distribution characteristics and transported by the corresponding cover. Finally, the prototype system is developed based on the Weixin IM open platform for validation and analysis of the unified steganographic communication model and algorithms.

英文关键词： Information Hiding;Instant Message;Cross-cover Steganography;Covert Communication;Steganography Model