Yeah, I’m sure that got your attention.

I’m referring to a phenomenon known to relatively few radio operators as a “numbers station”. Utilizing shortwave radios, amateur and (not-so-amateur) radio operators have been capturing these cryptic messages being broadcast over shortwave radio since as early as World War I. Often mechanically generated, they are broadcast in many languages, with different voices ranging from a man with an obviously fake English accent to that of a young girl.

The recordings themselves are downright creepy. Imagine it’s three o’clock in the morning and you’re listening to a shortwave radio. As you scan through the frequencies, you happen to stumble on what seems to be a melodic tone playing. The sound being broadcast could be anything from the first few bars of “The Lincolnshire Poacher” to a Spanish voice announcing “¡Atención! ¡Atención!. Following this introduction, a voice begins to recite sets of numbers. Often, the codes consist of numbers grouped into sets of five. Known to cryptographers as one of the most secure means of transmission, the codes are OTPs (One-time-pads).

A One-time-pad is a cryptographic system meant to carry the most secure of traffic. Because the encryption key changes with each use, the crypt in question is at best considered unbreakable. There is no algorithm to break because the key is unique each time it is used. So what is so interesting about these messages if they are considered unbreakable? It’s because someone is listening….

Most intelligence agencies do not publicly acknowledge that these numbers stations even exist at all. In one famous case, a group of Cuban spies were convicted in 1998 of espionage based on codes used to decrypt messages emanating from a numbers station in Cuba. Using the decrypted messages in court, U.S. prosecutors used the evidence to convict the Cuban nationals and inadvertently verified to amateur radio operators that they were, in fact, right on the money.

What used to be an inner circle of radio operators has exploded into large groups on the internet that actively follow the scheduled recordings to get the latest messages. In recent past, Wil Wheaton (from Star Trek:TNG) even wrote an article after he became fascinated by these curious transmissions.

Some have speculated that many of these messages may, in fact contain, disinformation. It is perhaps a perfectly viable system to have groups of code breakers scan the dial listening for codes that may or may not yield anything useful. If I wanted to keep the enemy guessing, this would be a fine tool.
Perhaps the most curious example of numbers stations is of a known Mossad (Israeli Intelligence) plaintext message broadcast that occurred this year. At 2200 UTC, 15 Mar 06 on 5339 kHz, Kilo Papa Alpha sent the message G1O2O3D4N5IG7H8T. This transmission is MUCH easier to read than most. Simply decrypt the message by removing the numbers to revealing the exciting message: GOODNIGHT.

Well, I suppose it beats “Be sure to drink your Ovaltine.”

Links:

spynumbers.com

http://www.simonmason.karoo.net/page69.html

http://en.wikipedia.org/wiki/Numbers_stations