Steganography

• Steganography  is the practice of concealing a file, message, image or a video within another file, message, image or video.

• In this method it hides secret behind the message.

• Various techniques are used:

                  1.    Character marking: Selected letters  of printed or typewriters text are overwritten in                             pencil. This are ordinarily unless the paper is held at angle to bright light.

 

                  2.    Invisible ink: A number of substances can be used for writing but leave no visible                                 trace until heat or some chemical is applied to the paper.

 

                  3.    Pin punctures: Small pin punctures on selected letters are ordinarily not visible unless                           the paper is held up in front of light.

                  4,    Typewriter correction ribbon: Used between lines typed with black ribbon, the result                             of typing with the correction tape are visible only  under strong light.

• Advantages:

               -It can be employed by parties who have something to lose should the fact of their secret                       communication is known.

• Disadvantages:

                -it requires a lot of overhead to hide a relatively few bits of information. Once the system                      becomes known to the public, it virtually becomes worthless.