A message within

This may seem to be an ordinary beginning to an ordinary article. It is not. There’s a secret message hidden here, in this very paragraph. It’s not in view, and its source is modern. But the art of hiding messages is an ancient one, known as steganography.

Steganography is the dark cousin of cryptography, the use of codes. While

cryptography provides privacy, steganography is intended to provide secrecy. Privacy is what you need when you use your credit card on the Internet – you don’t want your number revealed to the public. For this, you use cryptography, and send a coded pile of gibberish that only the web site can decipher. Though your code may be unbreakable, any hacker can look and see you’ve sent a message. For true secrecy, you don’t want anyone to know you’re sending a message at all.

Early steganography was messy. Before phones, before mail and e-mail, before horses, messages were sent on foot. If you wanted to hide a message, you had two choices: have the messenger memorize it, or hide it on the messenger. In fact, the Chinese wrote messages on silk and encased them in balls of wax. A more subtle method, nearly as old, is to use invisible ink. For example, “VOID” is printed on checks and other official documents in ink that appears under a strong ultraviolet light used for photocopies.

With the advent of photography, microfilm was created as a way to store a large amount of information in a very small space. In both World Wars, the Germans used “microdots” to hide information, a technique called “the enemy’s masterpiece of espionage.” A secret message was photographed, reduced to the size of a printed period, and then pasted into an innocuous cover message, magazine, or newspaper. The Americans caught on only when tipped by a double agent: “Watch out for the dots – lots and lots of little dots.”

All of these approaches to steganography have one thing in common – they hide the secret message in the physical object which is sent. The cover message is merely a distraction, and could be anything. Of the innumerable variations on this theme, none will work for electronic communications because only the pure information of the cover message is transmitted. Nevertheless, there is plenty of room to hide secret information in a not-so-secret message. It just takes ingenuity.

All of this sounds fairly nefarious, and in fact the obvious uses of steganography are for things like espionage. But there are a number of peaceful applications. The simplest and oldest are used in map-making, where cartographers sometimes add a tiny fictional street to their maps, allowing them to prosecute copycats. A similar trick is to add fictional names to mailing lists as a check against unauthorized resellers.

Most of the newer applications use steganography like a watermark, to protect a copyright on information. Photo collections, sold on CD, often have hidden messages in the photos that allow detection of unauthorized use. The same technique applied to DVDs is even more effective, since the industry builds DVD recorders to detect and disallow copying of protected DVDs.

Maybe, as in the movie “Star Trek” that I saw a week ago, there really is a message hidden somewhere for humans to find. In the real world, the place to look for such a message is space, and humans have been looking for quite some time. Marconi, the inventor of radio, speculated that strange signals heard by his company might be signals from another planet. To his credit, he was hearing these signals years before his competitors, but today they are known to be caused by lightning strikes. Today, the search for messages from space is underway on an unbelievable scale. Scientists have been looking for more than two years, with a telescope a thousand feet wide, but still they have found nothing.

Why have they found nothing? Maybe they haven’t searched enough. But there is a dilemma here, the dilemma that empowers steganography. You never know if a message is hidden. You can search and search, but when you’ve found nothing you can only conclude: Maybe I didn’t look hard enough, but maybe there is nothing to find.

The views expressed are strictly that of the author. Fajardo is the editor of the Saipan Tribune.