Spooks in the Wire

Salon is running a cool article about numbers stations - shortwave radio stations that broadcast encrypted messages to spies worldwide. I hadn't known about this, though it makes sense if you think about it - the U.S. government uses a similar scheme to communicate with nuclear subs at sea. The article includes links to a site which has .mp3 recordings of some of the transmissions. Spooky. They've even transcribed some messages for a possible crack attempt, though if the men in black are truly using one-time pads this seems (ahem) unlikely to succeed.

One time pads

Since WW2 it has been standard practice for field operatives sending and receiving traffic over totally insecure channels in this manner to use one time pads.

In the days of pencil and paper, a one-time pad was easier to apply (usually simple addition) than an algorithmic cypher, and of course infinitely more secure. I can't see that the computer era would do anything but facilitate it.

Nuclear submarines at sea still receive VLF carrier modulated (morse code style) transmissions for low volume traffic as they are one of the few things that penetrate easily to patrol depths. The Royal Navy still uses Rugby WT for this purpose, and I know there is a US equivalent.

Not that big of a mystery..

Couple of comments.

First would be that some enterprising shortwave listeners have indeed "DF'd" these things (traced them to their source). One major source of Spanish and English language numbers stations is (no surprise) some sort of State Department or CIA (nobody is quite sure) facility near Warrenton, VA. I believe a few years ago that Monitoring Times ran a story on the guys who figured this out.

Second, I would disagree with the statement that these are outmoded by satellite communications. You must remember that these are spy communications; as such, this is still the ideal medium. Why? First of all, should a field agent be caught/interrogated/searched, a shortwave radio is a much more anonymous travelling accessory than some strange satellite contraption. Reliability is also an issue. One can purchase a shortwave radio in just about any business district in any part of the world. What if an agent in the field loses his one-off satellite communications unit?

Given the security that one-time pads provide, there really isn't a disadvantage to still use shortwave. Atmospheric conditions and propogation are always an issue, and at times can be less than reliable, but some of these stations are pumping out some *serious* power, and repeat their messages many times a day on different bands.

These things have been infamous for years with the shortwave listening community. They're a little less obscure in Europe; there, the shortwave bands are much more populated (especially the low frequency ones) by broadcasters that occasionally, numbers stations have been known to have been pushed down into the standard broadcast bands. In fact, one of Stereolab's albums features a long sample of a numbers station (Transient Random Noise Bursts with Announcements if you're interested, available just about anywhere).

Ozone Pilot

Re: numbers stations

Numbers stations on shortwave have been active
for decades now. A lot of speculation has always
gone around regarding where they are coming from.
Years ago, the prevailing opinion was that they
were North-Korean spy stations broadcasting data
to field agents.

Shortwave listeners have always been very
interested in these spooky stations. There is
an organisation called World Utilitity Network
(WUN for short) and they publish a newletter every
week with this kind of information. It can be
found at http://www.wunclub.com/. For the
un-initiated: with the term utility station we
mean shortwave radio (30 MHz) users that are not
amateur radio operators.

There are many more resources out there on the
web. Without any doubt, they are rather exciting
to listen to. Sadly, the current tendency is that
shortwave communication is phases out by a lot of
these organisations in favor of satellite communications.

Re: numbers stations

Well, finding the location of these stations is
not so easy as you might say. Shortwave signals
are refracted by the atmosphere, which is the
first reason why it might be harder to pinpoint
the origin. In worst case, you aim your antenna
at the last bouncing point somewhere in the
earth atmoshpere.

The second reason is that because of the good
propagation conditions on shortwave, you can hear
the signal coming from two sides. The earth is
more or less round, so you have a short path
propagation and a long path propagation.

The third reason is that the signals don't necessarily(sp?) originate from the country that
is responsible for transmitting them. In the case
of US stations, it is very possible that they
are broadcast from one of the allied countries
in Europe or the Pacific.

Also, if you want to triangulate a shortwave
station by car, you must realise that it very
possible for shortwave stations to reach for
several thousands of miles. To illustrate this,
I spoke to an Argentinian operator from the
Netherlands only last weekend, and I only used
a power of 100W. These number stations habitually
use several kilowatts. Triangulating a station
which is several thousands of miles away needs
pretty large legs on the triangle.

Of course, this doesn't mean its impossible to
determine the direction of HF signals, its just
a nicer challenge ;)

Re:One time pads

I can't see that the computer era would do anything but facilitate it.

Not necessarily. A lot of people seem to have lost the distinction between sources of random data and sources of pseudo-random data in the era of the computer. Or discovered that what they thought was random really wasn't, even though they were really careful. Really, this has always been pretty much the only weakness of one time pads, though. And you can bet the folks broadcasting this stuff know where to get some grade A randomness. :-)

----
We all take pink lemonade for granted.

Numbers station sound files

Here's a link to a pretty cool site I've had bookmarked. It's got RealAudio files of numbers stations, as well as clandestine stations, unidentified broadcasts, etc:

http://www.cisquet.demon.nl/soundsframe .htm [demon.nl]