Steganography
Steganography is the art or practice of concealing a message, image, or file within another message, image, or file. The word
steganography combines the Ancient Greek words
steganos, meaning "covered, concealed, or protected", and
graphein meaning "writing". The first recorded use of the term was in 1499 by Johannes Trithemius in his
Steganographia, a treatise on cryptography and steganography, disguised as a book on magic. Generally, the hidden messages will appear to be something else: images, articles, shopping lists, or some other
cover text. For example, the hidden message may be in invisible ink between the visible lines of a private letter. Some implementations of steganography which lack a shared secret are forms of security through obscurity, whereas key-dependent steganographic schemes adhere to Kerckhoffs's principle. The advantage of steganography over cryptography alone is that the intended secret message does not attract attention to itself as an object of scrutiny.