random....

ok, so i have come to enjoy searching out wikipedia.org.......and clicking on random article..........the following was the second article to come up......the piece on osaka airport was not especially interesting....

Steganography is the art and science of writing hidden messages in such a way that no one apart from the intended recipient knows of the existence of the message; this is in contrast to cryptography, where the existence of the message itself is not disguised, but the meaning is obscured. "Steganography" is a Greek word and means covered or hidden writing. Its origins can be traced back to 440 BC. Herodotus mentions two examples of Steganography in The Histories of Herodotus[1]. Demeratus sent a warning about a forthcoming attacks to Xerxes by writing it on a wooden panel and covering it in wax. The second example is Histaeus who shaved the head of his most trusted slave and tattooed a message on his head. After his hair had grown the message was hidden. The purpose was to instigate a revolt against the Persians. Later, Johannes Trithemius's book Steganographia is a treatise on cryptography and steganography disguised as a book on black magic.

Generally a steganographic message will appear to be something else: a picture, an article, a shopping list, or some other "cover" message. Recent trends include steganographic coding inside of a transport layer such an MP3 file or a protocol such as UDP.

Steganographic messages are often first encrypted by some traditional means, and then a covertext is modified in some way to contain the encrypted message, resulting in stegotext. For example, the letter size, spacing, typeface, or other characteristics of a covertext can be manipulated to carry the hidden message; only the recipient (who must know the technique used) can recover the message and then decrypt it. Francis Bacon is known to have suggested such a technique to hide messages.