Abstract: The two-dimensional code is widely applied in production security and traceability, whose ownership is effectively protected by watermark and which is also correctly recognized. The watermark in the two-dimensional code has the good features such as the invisibility and robustness and so on. Firstly, the image of two-dimensional code is partitioned into some blocks, and then each block is transformed by DCT. Secondly, the center range of every block is further transformed by SVD. At last, the image of watermark is encrypted by Logistic and Arnold Transform, forming encrypted watermark which is embedded into feature vector of SVD, and then the image of two-dimensional code with watermark is formed. The extraction of watermark from the two-dimensional code with watermark is the inversed procedure of embedding watermark into the two-dimension code. The experiments show that the watermark in the two-dimensional code can effectively resist a variety of attacks, having excellent robustness, security and invisibility.

Key words: two-dimensional code, digital watermark, encryption, decryption

摘要： 二维码在产品防伪、追溯等领域中广泛应用，数字水印不仅能有效保护其所属权，而且不影响其正常使用。水印在二维码中具有不可见性、鲁棒性。首先对二维码图像进行分块，并对每个分块进行离散余弦变换（Discrete Cosine Transform，DCT）；其次对每一分块再取中心块进行奇异值分解（Singular Value Decomposition，SVD）；最后将经Logistic和Arnold变换加密后的水印图像置入到奇异值分解后的特征值中，形成置入水印的二维码。二维码置入水印的逆过程实现了水印的提取。实验证实了二维码中水印能有效抵抗图像多种攻击，具有良好的鲁棒性、安全性和不可见性。

关键词: 二维码, 数字水印, 加密, 解密