Steganography
Overview
Students will learn about and engage with steganography techniques and software.
Purpose
Images and other media can be used to hide information “in plain sight”. While the image is visible to anyone on the web, the secret message is only visible to those who know it’s there and how to read it.
Objectives
Students will be able to:
Preparation
Links
- For the Teacher
- http://tekbot.unl.edu/SPIRIT2/Tech/lessons/T062_RET_Hidden_in_Plain_Sight.doc
- https://github.com/DerekBabb/PictureEdit
- For the Students
Vocabulary
Teaching Guide
Getting Started:
Pixelation - Code.org
- https://studio.code.org/s/pixelation Steganography video - Computerphile:
- https://www.youtube.com/watch?v=TWEXCYQKyDc
Activity:
Manual Steganography Use the pixelation widget at Code.org to make a Favicon.
- The icon should be 16 x 16.
- Use 24-bits of color data per pixel.
Create a protocol for your Steganography.
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How are the bits modified on the image.
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How are the letters embedded in the image?
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How do I know when the message is done? Is there a “End of Message” or message length included?
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In a 16 x 16 image, what is the maximum message length?
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Write your protocol in plain language… how do you deal with the width/height data at the front of your favicon? How many pixels does it take for one letter?
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Hide a message in your favicon, post the binary in this file.
Once the image is created, use the least significant bit of each red, green, and blue channel to hide a message.
- https://www.rapidtables.com/convert/number/ascii-to-binary.html The data from your message should be spread across all of the RGB pixels in your Favicon.
Activity:
Use several available Steganography tools and compare:
- https://www.openstego.com/
- https://sourceforge.net/projects/stegtool/
- http://manytools.org/hacker-tools/steganography-encode-text-into-image/ (online)
Wrap-up
Discussion:
- How could steganography be used to thwart normal forms of surveillance?
- What are the dangers of sending info via steganography?
- What can companies like eBay use to prevent images uploaded for products hiding messages?
Assessment Questions
- How can steganography be detected?
- What are the biggest challenges to detecting steganography?
Extended Learning
Read: Blown to Bits - Chapter 3 Ghosts in the Machine
Blog Post:
Programming: Create Steganography in Java using the PictureEdit class or the Picture Lab APCSA
Standards Alignment
License
Cyber Security Curriculum 
is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.