Watermark embedding and extracting method for ultrashort Chinese text

The invention discloses a watermark embedding and extracting method for ultrashort Chinese text. The method comprises embedding and extracting two processes; the embedding process comprises two stages of identification of an embedding unit and embedding of secrete information; and the extracting process comprises three stages of identification of the embedding unit, extraction of the secrete information and watermark verification, wherein the identification operations of the embedding unit in the two processes are same. In terms of encoding, capacitance optimization, namely mixed binary encoding is adopted for synonym embedding unit; spread spectrum encoding is adopted in terms of Chinese characters de and le segments, thus, each embedding unit is fully utilized; and the hiding capacity of the ultrashort text is greatly improved. When the watermark information is extracted, the watermark verification technology is adopted to analyze whether the text to be detected is the text that is embedded, therefore, the false alarm rate during extracting the watermark information is effectively reduced.