Algorithm of XML document information hiding based on equal element

Information hiding can hide secret messages inside of image, video, audio, document, and other digital objects. The messages are invisible to general observers. Information hiding has become a new research hotspot of information security and copyright protection of digital multimedia recently. XML document is used as cover-media in XML document information hiding algorithms. A new algorithm of XML document information hiding based on equal element is presented, which overcomes the shortcoming of imperceptibility, robustness and hiding capacity of traditional XML document information hiding algorithms. According to the embedded rule, firstly, the algorithm turns secret message to a decimal integer, and then created equal element through sub-elements´ permutation and combination. According to mapping function between integer and equal element, the integer is embedded into the XML document by replacing the element with its equal element. The experimental results show that the algorithm does not change the size of XML document, and has good imperceptibility and robustness. The embedding capacity of the algorithm gets better increase than traditional XML document information hiding algorithms. So the algorithm could be used to covert communication and protect the content of XML documents.