[ News
| Homes
| Life
| Entertainment
| History
| Science
| Community
| Shop ]
| Sport
| Culture
| Cars
| Money
| Broadband
| Learning
| Health
| Dating
| Games ]
[ Text Only: Homepage ]
[ Graphical: Channel4 Homepage ]
In addition to hiding the meaning of her correspondence, a process known as cryptography, Mary Queen of Scots also hid the letters themselves, a process known as steganography. Mary's letters were hidden inside the bung of a beer barrel which was then allowed to pass freely into and out of her prison.
Steganography is an ancient science. Some of the earliest accounts of its use date back to Herodotus, who chronicled the conflicts between Greece and Persia which occurred in the fifth century BC. Herodotus also recounted the story of Histaiaeus, who wanted to encourage Aristagoras of Miletus to revolt against the Persian king. In order to securely convey his plan, Histaiaeus shaved the head of his messenger, wrote the message on his scalp, and then waited for the hair to regrow. This was clearly a period of history that tolerated a certain lack of urgency. The messenger, apparently carrying nothing contentious, could travel freely. Arriving at his destination, he shaved his head and pointed it at the recipient.
In the two thousand years since Herodotus, various forms of steganography have been used throughout the world. For example, the ancient Chinese wrote messages on fine silk, which was then scrunched into a tiny ball and covered in wax. The messenger would swallow the ball of wax. In the 15th century, the Italian scientist Giovanni Porta described how to conceal a message within a hard-boiled egg by writing on the shell with a special ink made with an ounce of alum and a pint of vinegar. The solution penetrates the porous shell, leaving no visible trace, but the message is stained on the surface of the hardened egg albumen, so it can be read when the shell is removed.
Steganography also includes the practice of writing in invisible ink. As far back as the first century AD, Pliny the Elder explained how the 'milk' of the thithymallus plant could be used as an invisible ink. Although transparent after drying, gentle heating chars the ink and turns it brown. Many organic fluids behave in a similar way, because they are rich in carbon and therefore char easily. Indeed, it is not unknown for 20th-century spies who have run out of standard-issue invisible ink to improvise using their own urine.
Today steganography is becoming increasingly important. A totalitarian regime might ban cryptography so that it retains the power to monitor the communications of its citizens. However, it is much harder for a government to ban steganography, because it is tough to ban something that by definition is difficult to find.
Steganography
Graphic
version
Includes layout and images.