Reversible Text Watermarking Algorithm Using Prediction-error Expansion Method

In order to avoid the permanent change of the text content caused by watermark embedding, this paper proposes a reversible watermarking algorithm for Chinese text document using prediction-error expansion. The algorithm takes the sentence as the unit, through the context collocation degree to select the words that can be replaced, using prediction-error expansion and chaos sequence to realize embedding. Results show that this algorithm not only has the higher security, but also can extract watermark effectively, and restores the original text intact.