Steganography is the science of hiding information. It can be used in many ways, and for many purposes. I'm going to show you one tonight and give you some resources if you are interested in learning more on the subject.
Tonight I'll show you how to hide a text file in a graphic. I use this for hiding all of my passwords, but you could use this for anything you wanted to hide.
Here's a picture of an apple:
Here's the same picture with a text file stegged in it:
Can't tell the difference, can you?
A real simple steganography program is Steghide - Steghide Link
Download Steghide, install it and download the second apple photo (apple.jpg).
To extract the hidden file do:
Open secret.txt to see the contents.
$ steghide extract -sf apple.jpg
Enter passphrase: gamahiro
wrote extracted data to "secret.txt".
To steg a file into a graphic do:
Easy. Now go hide everything from your parents
$ steghide embed -cf AnyPicture.jpg -ef SomeSecretFile.txt
embedding "SomeSecretFile.txt" in "AnyPicture.jpg"... done
Here are some links for other steganography software and resources:
Feel free to ask if you need help with any of this.
Hope this helps.