Cryptography

The History and Mathematics of Codes and Code Breaking

Tag: steganography

Nothing to Hide

Chapter one of Simon Singh’s The Code Book begins with two stories. The first one is about Mary Queen of Scots and the second one is about Demaratus, an exiled Greek who nevertheless worked to communicate secretly with his homeland. While both of their stories were told to establish a theme of secret writing, the two stories have very little else in common. 

Demaratus’s story is one of a brave and cunning man who, upon learning of a Persian plot against his homeland, found a way to conceal the existence of his message so it could reach its destination safely. His heroics allowed the Greeks to prepare a fleet to meet the advance of Xerxes’s fleet and defend themselves from an attack that would otherwise have caught them completely off guard. Demaratus’s successful use of steganography, the act of concealing the existence of a message, allowed him to save Greece from a major military defeat. 

The story of Mary Queen of Scots did not end as pleasantly for Mary as Demaratus’s did for the Greeks. Mary had concealed her message using cryptography rendering it unreadable to those who did not have the cipher, rather than by hiding its existence in the first place. The fate of her life hung, not on whether or not her message would be discovered, for it already had been, but rather on whether it could be deciphered. Her encrypted message was, unfortunately for her, in the hands of a man named Thomas Phelippes, one of the finest cryptanalysts of his day. He eventually succeeded in decrypting the message and laid bare a plot by Mary to assassinate Queen Elizabeth and take the English throne. She was relieved of her head shortly thereafter. 

There are several differences between these two stories. Obviously, one story sees the message successfully and discreetly transported to its intended audience, while the other one has the message discovered and decrypted. In addition, the British one is likely more factual, as it is based on historical data and physical records, rather than the legends and folklore that likely drive much of Heroditus’s account of Demaratus. Finally, the type of secret writing involved varies between the two. In the Ancient Greek story, Demaratus used steganography to conceal the existence of his message whereas Queen Mary of Scots relied on cryptography to keep the contents of her message a secret even once the message had been discovered.

Hidden In Plain Sight

While almost everything on Elonka Dunin’s website seemed very interesting, the one thing that stood out the most to me was her presentation on steganography. She goes into great detail on what exactly steganography is, and whether or not terrorists were truly utilizing steganography to spread hidden messages. Elonka found that to this date, Al Qaeda’s members have never utilized digital steganography to spread messages. Although there was great speculation and some instances that pointed to this being true, Elonka found no convincing evidence that this was the case.

Elonka also goes on to show interesting examples of steganography, such as the “sekrit” page. The page had numbers that translated into an ISBN number for the book “Disappearing Cryptography, which contained information on steganography. The page also featured anagrams and steganographically hidden small files, which contained information on opening a message hidden elsewhere in the code. She also showed numerous examples of modern steganography, especially hiding messages inside pictures.

After showing examples of steganography and how it is employed, Elonka detailed ways in which to defeat steganography. She highlighted the “Three D’s of Defeating Steganography” – Detection, Decryption, and Deletion. Detection involves examining an image for irregularities or changes in patterns. Decryption involves obtaining a password or information about how the message was encrypted. Finally, deletion involves cropping an image or changing an intercepted message in some way to remove the stegonographic image. Although you won’t be able to decipher it, the intended receiver will no longer be able to find the message either.

I enjoyed going through Elonka’s presentation as it presented a lot of cool information about steganography, which we haven’t been able to cover in depth in class. She covered various forms of steganography, how to beat it, and intriguing examples of steganography in use. Especially interesting were the various sites and programs that could create steganographically hidden messages for you, with the user only needing to provide the message. While the ciphers covered in class, such as the monoalphabetic and vigenère ciphers, were difficult but not impossible to beat, steganography could be a powerful way to protect information. If you have no idea where to look or how to begin, the message may easily skip past you without you even realizing a message was present.

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