Steganography ( steganos - covered; graphie - writing ) is the art of hiding a message within another message. An example would be hiding a text file in the data of a graphics file.
Compare this to cryptography. Imagine Ann wants to send a message to Bob. Ann decides to encrypt the image and send it. This means that if Eve intercepts the message she'll know it exists, but she will not be able to decrypt it. With steganography Eve will not know the message exists, but if she did she would be able to read it.
Steganography has several failure points.
- Poor choice of cover data
- Poor preparation of hidden data
- Poor choice of method of hiding
Some steganographic software available produces 'hidden' data that is trivially easy to detect; there are steganography detection softwares available.