So you think you are sneaky? Can you hide a file inside another without making it look different from the outside? Well, you can learn how if you read this tutorial.
The art of hiding information from anyone except from the intended receiver has been used for many centuries. Hiding information by embedding it in other, seemingly innocuous information is known as steganography, a word that means "covered writing" in Greek. Today, steganography applications can hide one file within another on a computer. Steganography applications are available on many different platforms, including Windows, Linux, and *BSD.
You need two files in order to use steganography. The first one is the innocent-looking file, called the "cover file." A cover file can be in many graphical or audio file formats, such as .bmp, .jpeg, and .wav.
The second file is the secret file you want to hide in to the cover file. There are no restrictions on the file format of the secret file.
Cover file formats are often associated with large files sizes, which is important in getting steganography to work properly. To hide a secret text of 200KB, the cover file must often be at least 1MB in size. Most stego applications will deliver a warning if the cover file size is too small to effectively hide the secret text.
A successful steganography file must never raise any alarms when a person looks or listens to the file with the embedded secret file. Without such an alarm, detailed inspection is rare; how often does you inspect the attachments your corporate firewall handles?
