Steganography

You’re listening to A Way with Words, the show about language and how we use it. I’m Grant Barrett.

And I’m Martha Barnette.

The ancient Greek historian Herodotus once wrote about a tyrant who lived in the late 6th century B.C.

And this tyrant named Histiaeus wanted to get a message to a fellow tyrant in the region to conspire to revolt against the Persians.

But if you’re going to send a message like that by a messenger, you don’t want to get caught, right?

So he devised this clever way, how do you get a message like that to somebody else in writing?

And he figured out a way to do it, which was that he summoned his most faithful servant,

Shaved the guy’s head, tattooed the message on the guy’s head, and then let his hair grow back,

And then sent the servant off to this other tyrant, his fellow tyrant, to deliver the message by saying to the tyrant,

Hey, shave my head, there’s a message there.

Pretty smart, right?

Right, right.

Must not have been urgent.

I guess not.

But I thought that was a really cool story,

And it turns out that there’s a term for this kind of covered writing.

Oh, interesting.

And that is steganography.

Oh, I know that word.

I figured you would.

I was going to point out that it comes from the Greek word steganos,

Which means covered and is related to the name of the dinosaur that’s covered.

Stegosaurus.

Exactly.

And scale, or plaques almost, right?

Yeah, those bony plates, stegosaurus and steganography.

But I figured you would be familiar with modern-day steganography.

Yeah, so this is a method of encoding a message into something that looks innocuous.

Typically, you include it in an image where you just say, oh, that’s a really beautiful landscape that you’ve sent me here.

Why did you send me a picture of a mountain lake?

I have no idea.

But when you decode it with the right software, it will deliver the message that was hidden inside the bits and bytes all along.

Exactly.

Or you can just make it really, really small and the person enlarges the image.

Or you and I have talked before about how if you’re building a website, you can hide text on the website if the background is white.

And the text is white.

Yeah.

You use a font and color it white, then it’s invisible until you mouse over it.

And some puzzle sites do this as well.

Oh, really?

They can have the question on the page, and then you highlight on the screen to see the answer.

Oh, that’s also steganography.

Very easy way to do without any extra code.

Interesting.

Yeah, the image steganography, you can actually practice it yourself.

Just Google around.

You’ll find some software out there, and you can have fun sending secret messages to your friends.

Oh, how cool.

Also, the bad guys use it for what that’s worth, but you don’t have to be a bad guy to do it.

Oh, that’s very interesting.

I knew you would know the word steganography.

Sure.

This is a show about words and language and how we talk to each other and apparently how we send ciphers back and forth.

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