I read a book review recently of some musically inclined human rights activists in the last half century that wanted detailed information about the persecution of Jews in the Soviet Union (now Russia and the semi-independent republics). They made one or more trips behind the “Iron Curtain.” They wanted details like the names, addresses and other information on persecuted Jews that they dare not commit to paper, lest the border guards and the KGB find the notes and arrest them.
So, using musical notes on musical composition paper, they devised a code that linked the musical notes to certain letters, words or numbers. To some careless guard, who could not read music, it would look like ordinary sheet music. But a musician would see it as utter gibberish. In a sense, this is an example of the term steganography which is a hidden message carried inside an ordinary-looking object (the sheet music), and no one knows it is there, even though they are looking at it. Wikipedia notes:
The word steganography comes from two Greek words: steganós (στεγανός), meaning "covered" or "concealed," and -graphia (γραφή), meaning "writing."
Here’s another example:
The Bayeux Tapestry is an illustrated cloth 230 feet long which was embroidered sometime after the eleventh century and it depicts the Norman invasion of England including the Battle of Hastings. Different panels portray different events, such as people dining and dying, and in one panel, people are pointing in the sky at what would centuries later be called Halley’s Comet.
Look at the two photos of the comet. They look identical in every way. Yet, the panel on the left also contains Lincoln’s Gettysburg Address delivered on November 19, 1863. I might have included the recipe for my mother’s jelly doughnuts instead, but I decided on the Gettysburg address with 271 words to it. No matter how long you stare at the photo, you will not see it, unless you open the photo using Notepad, Notepad++, TextEdit (in plain-text mode) or some other any hex editor.
Again, I could have just as easily included a cheat sheet for the GTA 3 game or the current menu for Chipotles. But who looks for hidden messages that are—in some sense—in plain sight?
For the sake of the example, I’ve included the annotated lines of code (see footnote).1
Footnotes
1The last stretch of the picture, up to and including the IEND chunk (shown as raw bytes, since this part isn’t text):
…\x9a\xa0<[\xc8\xd8\x0e\xc8\xb6C\xff\x07\x13\xee\x040\xcb\x82\xf7^ \x00\x00\x00\x00 IEND \xaeB`\x82
The \x00\x00\x00\x00 just before IEND is the chunk’s length field (zero, because IEND carries no data). The four bytes after IEND (ae 42 60 82) are its checksum, and that is where the picture officially ends.
Everything after that point is the hidden text:
–BEGIN HIDDEN TEXT–
Gettysburg Address (Bliss copy), Abraham Lincoln, November 19, 1863
Four score and seven years ago our fathers brought forth on this continent, a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal.
Now we are engaged in a great civil war . . .
–END HIDDEN TEXT–
