In this paper, a novel information hiding method is proposed to embed data in the Word documents that use OOXML format. The 2007 version and more recent versions of MS Word are all based on the OOXML format. The main document body of OOXML document consists of the text elements that correspond to the content of the document. It is found that, in the OOXML format, the printable text in an element can be “split” by separating the element into multiple elements. The digital code of the information determines if the adjacent characters in the text will be “split” or not, so as to achieve the purpose of information hiding. Since the format and all the other properties of the text in the OOXML format document is unchanged after the embedding, the embedded information is imperceptible. The code of the information is embedded circularly to enhance robustness. Experiments show that the proposed method can deal with many kinds of attacks, including “content”, “save as”, “copy” and part of “format”. The proposed method can be used in information security and copyright protection for OOXML format documents.

A robust text watermarking approach has been proposed in this paper, in which the watermarks are embedded into the text by the transformation of characters' RGB-style color in the OOXML format document. To get high watermark embedding capacity, two bits of the watermarking information are embedded between every two characters. The initial text content of the document is not changed after the embedding because of the good characteristics of OOXML format and the subtle adjustment of characters' color, which ensure the good imperceptibility of the watermarking method. Most attacks such as “copy”, “save as”, “insert” and “delete” operations can be resisted by the proposed approach, and the location of the “insert” and “delete” operations can be detected by redundant embedding of the watermarking information. The proposed approach can be applied to files in “docx” and “doc” format.