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Issue 20.6 ('Nashville 2022')
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FEATURE

Exploring Stenography, Part 3

Comparing a Stenographic Picture

Issue: 20.6 (November/December 2022)
Author: Eugene Dakin
Author Bio: Eugene works as a Senior Oilfield Technical Specialist. He has university degrees in the disciplines of Engineering, Chemistry, Biology, Business, and a Ph.D. in Chemical Engineering. He is the author of dozens of books on Xojo available on the xdevlibrary.com website.
Article Description: No description available.
Article Length (in bytes): 20,665
Starting Page Number: 14
Article Number: 20603
Resource File(s):

Download Icon project 20603.zip Updated: 2022-10-31 22:45:13

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Excerpt of article text...

This article is part 3 of our series on stenography and this time we'll be showing how to compare a modified stenographic picture with the original picture. The whole purpose of stenography is to hide or minimize the hidden information in a picture. This program determines differences between an original picture and the stenographic version and provides change information as well as a change picture. A program has been created in native Xojo code to compare these two pictures. This article and example explicitly work with LSB (Least Significant Bit) Stenography, and can be used for picture comparison of other types.

What is Stenography?

Steganography is the ability to hide and retrieve text, an image, or other data that is a secret, into a picture that is not a secret. Steganography also works by attempting to conceal that a secret message even exists.

Steganography occurs in the world of spies, hackers, and other activists. One of many legal areas where Steganography exists is when selling online pictures and a hidden watermark is added. If you download or attempt to copy a picture, there are deliberate hidden messages in the picture to record who downloaded the picture.

Using the Xojo programming language, we are able to hide the message without anyone knowing that a message was actually sent. That was covered in Part 1 of this article series. Part 2 showed how to retrieve the hidden picture. Today in part 3 we will compare an original picture with the steganographic picture to show a numerical change and visual changes.

Our example uses an original PNG image, and the lowest color bit will be retrieved that will contain the information of the picture that was hidden. Changing the LSB in the original picture has an almost unnoticeable change to the image.

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