自适应视频内容的隐密信道方案

An adaptive covert channel scheme based on video content

文章提出了一种自适应视频内容的隐密信道方案。该方案从视频图像纹理估计和视频帧间运动估计两个方面对原始视频内容进行了复杂度分析,选择视频序列中那些复杂度高的图像区域作为待隐密的候选载体集合;隐密通信信道依赖于临时共享密钥从候选集合中随机采样;构建的隐密信道容量自适应于集合中载体复杂度;结合了视频量化压缩编码过程,将事先置乱的密信嵌入在载体图像的离散余弦变换(Discrete Cosine Transform,DCT)/量化系数上,形成含密的视频数据流。最后,方案提出了共享密钥的算法,解决了密信提取需要原始载体的问题,接收端则根据临时共享密钥对视频进行解码,在不影响视频正常播放的同时正确提取出密信。该方案的优点是隐密信道的容量随着视频内容的变化而自适应地变化,密信散布在复杂度高的视频序列图像区域,隐蔽性高。同时,嵌/解密过程和视频压缩编/解码相结合,保证了密信的嵌入不明显改变视频的传输码流长度。实验结果表明,方案有较小的误码率和失真率,但是隐密传输的可靠性和安全性较高。

An adaptive covert channel scheme based on video content is proposed.The video content complexity analyzed from the video frames texture/edge complex estimation and video intra-frame motion estimation,we choose the high complexity blocks of video frames as the covert candidate collection;A covert channel sampling depends on the shared secret key temporarily;The capacity of covert channel adaptive to embedded blocks’complexity;Combination the video compression process,we embed the preprocessed secret messages into the carriers’DCT(Discrete Cosine Transform)/quantitative coefficients and then get the embedded video stream;Finally,the algorithm of shared secret key is proposed,solved the problem of extraction process needs original covert.The receiver used secret key to decrypt video,at the same time of video playing to extract the secret messages;The advantage of this scheme is that the embedded capacity change as the video content variation,secret messages spread in areas of high complexity has high concealment.Combined with the video compression standard,the covert video coding length has no obvious change compared with the original video.The experimental results indicate that the proposed algorithm has smaller error rate,less distortion rate,higher reliability and higher security in transmission.