摘要
基于流速率的直序扩频(DSSS)流水印技术在嵌入多比特的水印信息时采用同一伪随机(PN)码,使得已标记数据流具有自相似性,均方自相关(MSAC)攻击通过单条已标记数据流就可检测DSSS流水印的存在性,严重破坏了DSSS流水印的隐蔽性。PN码正交化方法虽可消除已标记数据流的自相关性,进而抵御MSAC攻击的检测,但正交PN码难以生成,应用范围受限。为此,提出基于PN码随机化的MSAC攻击防御方法,在向目标数据流嵌入每个水印位时均采用随机选择的不同长度的PN码进行扩展,使得已嵌入DSSS流水印的数据流速率的均方自相关不再呈现周期性峰值,进而可在MSAC攻击面前保持隐蔽性。理论分析与实验结果表明,基于PN码随机化的MSAC攻击防御方法可有效抵御MSAC攻击的检测,且所采用的PN码易于生成,便于部署和应用。
The flow rate based direct sequence spread spectrum( DSSS) flow watermarking technique used the same pseudorandom( PN) code to modulate the multi-bit watermark signal,as a result,the DSSS watermarked flow had self-similarity,and the mean-square autocorrelation( MSAC) attack could detect the existence of the DSSS flow watermark by using single DSSS watermarked flow,which seriously destroyed the stealthiness of the DSSS flow watermark. Although the PN code orthogonalization method could eliminate the autocorrelation of the DSSS watermarked flow and thus resisted the MSAC attack,however,the orthogonal PN codes were difficult to generate,which limited its application range. Therefore,this paper proposed the PN code randomization based MSAC attack resistance( PNCR-MAR) method,when it embedded the watermark signal into the target flow,the PN codes of different lengths,randomly selected from a PN code set,and used to spread each watermark bit,so that the mean-square autocorrelation of the flow rate of the watermarked flow no longer exhibited periodic peaks,as a result,this PNCR-MAR method could defend against the MSAC attack. Theoretical analysis and experimental results show that this proposed PNCR-MAR method can effectively resist the MSAC attack,and the adopted PN codes are easy to generate,which is suitable for deployment and application.
作者
许新忠
张连成
燕菊维
Xu Xinzhong;Zhang Liancheng;Yan Juwei(Henan Vocational College of Art,Zhengzhou 450011,China;State Key Laboratory for Mathematical Engineering&Advanced Computing,Zhengzhou 450001,China)
出处
《计算机应用研究》
CSCD
北大核心
2020年第6期1789-1793,共5页
Application Research of Computers
基金
国家自然科学基金资助项目(61402526,61402525)。
关键词
流水印
直序扩频
均方自相关攻击
PN码正交化
PN码随机化
flow watermarking
direct sequence spread spectrum
mean-square autocorrelation attack
pseudo-noise code orthogonalization
pseudo-noise code randomization
