Text Encryption Technique Based on Robust Image Watermarking
基于鲁棒图像水印的文本信息加密技术

The JND (just noticed difference) threshold matrix based on block was calculated by a new human visual model,and then a text encryption algorithm based on image-adaptive public watermarking technique operating in DWT domain was presented. Firstly,the text in a file was encoded with Reed-Solomon codes for robust and transferred into a binary sequence,which could be permuted randomly to a final watermark. Then,two neighboring blocks were selected from the Hilbert scanning sequence of the host image blocks in turn,and transformed by 1-level DWT. By JND,the final watermark was embedded into the host image by modifying the average values of the two corresponding subbands. The experimental results show that the embedded watermark is invisible to human eyes at a low PSNR,and the algorithm is robust to common image processing operations,especially to signal enhancement. The conclusion is that the algorithm is effective and practical.