基于马尔可夫链蒙特卡罗采样的双密钥盲水印算法

Blind watermarking algorithm of double keys based on Markov chain Monte Carlo sampling

为了更好地提高水印算法的安全性,提出了一种基于两种形式密钥的强鲁棒盲水印算法。首先对水印加密,然后将每块载体的第一个奇异值组成矩阵Q再分块离散小波变换(DWT)获得四个子带,通过对四个子带进行马尔可夫链蒙特卡罗(MCMC)采样决定第k个水印位量化嵌入到矩阵Q的第k块低频、水平、垂直和高频子带中的一个并记录当前嵌入子带的密钥位,这样做不仅使水印位随机分配,而且提高了水印算法的安全性。实验结果表明,所提算法在满足不可见性的条件下,不仅对常规的图像攻击具备较强的鲁棒性,而且在水印嵌入过程中通过MCMC采样实现了用不同的密钥嵌入,提高了水印算法的安全性。

In order to improve the security of watermarking algorithm, a robust blind watermarking based on two forms of key was proposed. Firstly, the watermark was encrypted by a key, then matrix Q was consisted of the first singular value of each block carrier and block Discrete Wavelete Transform （DWT） again to acquire four subbands, the k-th watermark bit was chosen to be embedded in the k-th block＇s low-frequency, horizontal, vertical and high-frequency subbands of matrix Q by Markov Chain Monte Carlo （MCMC） sampling of four subbands and record the current key of embedded subband. It not only made watermark bit randomization, but also improved the safety of the watermark algorithm. The experimental results show that the proposed watermarking has strong robustness against conventional attacks under the condition of satisfying invisibility, meanwhile, it enhances the security of the watermark algorithm, which is embedded with a different key by MCMC sampling in the watermark embedding process.