1. Steganography
ETPRO 2010

2. What does this mean?
Steganos (Covered)
Graphie (Writing)
ETPRO 2010

3. Why Greek? They used this technique!
In 440 Demaratus, used a covered writing technique to send a warning about an attack to Greece. At that time wax tablets were used to write on. The wax could be melted and the tablet could be used again. Demaratus, wrote on the wooden backing of a wax tablet before the beeswax was applied.
Histiaeus tattooed the shaved head of his most trusted slave and sent the slave to deliver his message once the hair had grown back.
Ask students if they have ever heard of other “covered writing” Students might say:
Invisible ink
Microdots
Altered Digital Files
ETPRO 2010

4. Invisible Ink in the Revolutionary War
Podcast: Invisible Ink and More: The Science of Spying in the Revolutionary War
British spies would mark their letters with an A for acid, or F for fire to tell the recipient of the letter whether the heat from the flame of a candle, or washing soda ( an alkaline chemical Sodium Carbonate is currently used in water softener)
The author would write a letter and in between the lines he or she would write in invisible ink. The recipient had to be very careful not to smudge the writing.
ETPRO 2010

5. What could you use to make invisible ink?
Good spies use stuff that is normally found around the house to make invisible ink. That way, if the materials are discovered, they won’t be revealed as spies!
Give students the steganography worksheet and let them practice different steganography methods.
Method 1: Use the white candle on the paper, the highlighter will reveal the message.
Method 2: Use the skewer to scratch a message on piece of paper (the paper may need to be folded several times to provide adequate relief to the message. Use the crayon to reveal the message
Method 3: Combine the baking soda in the water and wrote on the paper with a cotton swab. When it is dry, paint on purple grape juice to reveal the message.
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6. The Special Operations Executive Training Manual
Invisible Inks should be:
Water Soluble
Non-volatile, and no smell
Leave no residue (i.e. Be invisible if you tilted the paper)
Not visible under ultra-violet light
Not deteriorate or cause the paper to deteriorate over time
Be revealed by unknown developers
Use as few developers as possible
Develop using something other than heat
Easy to obtain so that it looks innocent if someone should have it
Ask students to assess the methods they tried as a real spy would.
Method 1 (White Candle):
Pro:2,4,5,7, 8, 9
Con:1,3,6,
Method 2 (Skewer):
Pro:2,4,5, 7, 8, 9
Con:1,3,6
Method 3 (Baking Soda and Water)
Pro:1, 2,4,5,7, 9
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7. MicroPrinting
Image from:
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8. Hiding the entire Declaration of Independence in one dot!.
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9. Computer Steganography
Altered Images
Could you tell a fake picture from a real picture?
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10. Which is Fake? Which is True?
If time permits take the Urban legends image quiz at
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PIC SITE

11. ETPRO 2010

12. circa 1860: This nearly iconic portrait of U. S
circa 1860: This nearly iconic portrait of U.S. President Abraham Lincoln is a composite of Lincoln's head and the Southern politician John Calhoun's body. Putting the date of this image into context, note that the first permanent photographic image was created in 1826 and the Eastman Dry Plate Company (later to become Eastman Kodak) was created in 1881.
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13.
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14. Using a Steganography Tool: Can you tell the difference?
Included in the content files is a great video on steganography. It shows how whole files can be merged into a photo without changing the image.
Here is a good article about steganography:
Steganography can be used for good or evil. This means that sites that host steganography can be loaded with malware. It is best not to search for or install this software on your machine.
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15. S Tools Can Hide a Text file in a .BMP Photo
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16. Using the same tool and the password, reveals the hidden file
ETPRO 2010