Implementation of Steganography on Text Media using Line-Shift Coding Method and Centroid Method.

Abstract

Steganography is an information hiding technique using a certain media, such as text, sound, and images to make the message looks like another form. Nowadays, steganography is being widely used on digital document. Along with the increased use, type of attack that is used to take or damage the message done by the other parties become varies, for example, the use of scanner and printer to print a digital document with the purpose to erase the messages that have been inserted in the document. Therefore, it’s necessary that the steganography method being used has to be resistant to the process of printing and scanning, one of which is line-shift coding method. Line-shift coding method is a method that adding series bits of message in the document by moving even line in a paragraph vertically. Research was conducted to apply this method in the PostScript document. Results from this research include the estimation analysis for the size of messages that can be inserted in several different font sizes. When the font size is larger, it can be estimated that the characters of message that can be inserted are increased. In this research, line-shift coding method is proven resistant to the printing process, the difference in the quality of printing, which are fast normal (300 dpi), best (600 dpi), and maximum dpi (1200 dpi), a photocopy process up to two times, and resizing image attack to 700 * 963 pixels and up. Yet, this method has fail to pass resizing image attack up to 700 * 963 pixel, different slope angle attack and the cutting image attack. Keywords: steganography on text, Line-Shift Coding method, Centroid method.