-: In this demonstration,
you're going to learn how steganography is used
to hide data within other data.
Steganography is the art and science
of hiding message within other messages.
If you've ever seen an old spy movie,
where one spy takes out a classified ad in the newspaper
and the first letter of each word
makes up the secret message,
something like meet at six?
This is a version of steganography.
Note that data isn't going to be encrypted when you do this,
it's just going to be hidden inside another message.
And if you know what the key and what your looking for,
then it's really easy to see the message
inside wherever it's being hidden.
So, in the case of my newspaper example,
writing down the first letter of each word,
gives you the secret message.
Now basically, if anybody knows where to look,
they can easily pull that data back out.
So, let's jump into the lab environment
and see how easy it is to hide some data
inside a standard photograph using a steganography tool,
and then getting that back out on the other side.
To conduct this demonstration,
we're going to load a steganography program
up inside our web browser.
You can try this at home if you want to.
All you have to do is go to this website
as you see on the screen,
stylesuxx.gethub.io/steganography/ and hit enter.
When you get to the screen,
you're going to be asked to choose a file.
So, I'm going to go ahead and choose a file off my desktop
which is my logo, Dion Training.png.
And then you're going to type in
whatever the message is you want to hide.
This is a secret message
for my students only.
Steganography is fun.
Okay, so we're going to go ahead and hit encode,
and when you do that,
you'll see what your binary representation
of your message is.
You'll see the original you had.
You'll see the normalized version of it.
And notice these logos all look the exact same,
and then you'll have the hidden message version.
If you right click that and save it,
you can go ahead and save it to your desktop,
and I'm going to do it as Dion training message.
And you'll see it there on my desktop.
Now, if I look at these two files side by side,
we'll have the Dion training one up here,
and the hidden message one right here.
They look identical in every way don't they?
Right, exactly, they do.
And so, if we go ahead and close these,
we can actually look at the file size of them.
And so, here we have the one on the left here
or excuse me, the one on the left is Diontraining.png
which is the original.
And you could see the file size or the dimensions of it
are the exact same as the new one.
We haven't changed that at all.
But, we did change the file size,
and we went from 74kb down to 57kb.
Why if we put more information, did the file size shrink.
Well it's because the way they re-encoded it
to make sure the images looked exactly right
and the compression they used.
Sometimes the file size will get bigger as well,
but it is very infrequent
that you'll see the same file size.
So this may be one way that we know
the file has been changed.
Now, if we want to see the actual message inside of it,
let's go over here to decode.
And let's go ahead and choose the original file,
and if we hit decode, you'll see that there is
no message inside that one.
See there is no hidden message.
It came out garbage because there was no hidden message,
but if I choose the one that we hid the message inside of.
We hit open, and hit decode,
you'll see that our hidden message comes right back.
This is a secret message for my students only.
Steganography is fun.
And so, if you want to play with this, you can.
You can go through and do some of this,
and send it to your friends
and have them send you messages back.
But remember, the information isn't encrypted
when you're doing the steganography.
You're hiding it in plain sight.
So, if I actually decide to open up
Diontrainingmessage.png,
the one that has this hidden message in it,
inside of a hex editor,
you could actually find that message hidden inside of it.
It's not encrypted.
And so, steganography is covered in the cryptography section
because it is considered a way of hiding information.
But it is not true encryption.
(digital music)