What are the popular approaches of text steganography?

There are various approaches of text steganography which are as follows −

Line Shift − In this method, secret message is private by vertically changing the text lines to some degree. A line decided has two clear control lines one on side of it for identifying the direction of movement of the marked line. It can hide bit 0, a line is changed up and to hide bit 1, the line is changed down.

Determination of whether the line has been changed up or down is completed by computing the distance of the centroid of apparent line and its control lines. If the text is retyped or if a character recognition program (OCR) is utilized, the hidden data can get destroyed.

White Steg − This technique uses white spaces for concealing a secret message. There are three methods of hiding information utilizing white spaces.

In Inter Sentence Spacing, it can place individual space to hide bit 0 and two spaces to hide bit 1 at the end of each removing character. In End of Line Spaces, fixed number of spaces is added at the end of each line.

For instance, two spaces to encrypt one bit per line, four spaces to encrypt two bits and so on. In Inter Word Spacing approach, one space after a word defines bit 0 and two spaces after a word define bit 1. But, uncertain use of white space is not clear.

Spam Text − HTML and XML files can also be used to protect bits. If there are different starting and closing tags, bit 0 is interpreted and if an individual tag can be used for starting and closing it, therefore bit 1 is interpreted.

In another approach, bit 0 is defined by a lack of space in a tag and bit 1 is defined by locating a space within a tag.

Word Shift − In this approach, private message is hidden by changing the words horizontally, such as left or right to define bit 0 or 1 respectively.

Words shift are identified using correlation method that consider a profile as a waveform and determines whether it originated from a waveform whose central block has been changed left or right.

This approach can be recognized less, because change of distance among words to fill a line is completely frequent. But if someone understand the algorithm of distances, it can compare the stego text with the algorithm and acquire the hidden content by utilizing the difference. It can also, retyping or using OCR programs destroys the hidden data.

SMS-Texting − SMS-Texting language is a set of abbreviated words used in SMS. It can hide binary information by utilizing full form of word or its abbreviated form. A codebook is create which include words and their correlating abbreviated forms.