Tag Archives: Cuban Numbers Stations

Shortwave Numbers Stations on The Daily Beast

SWLingPost-Numbers1

Interest in shortwave numbers stations seems to wax and wane. We’re currently going through a period of increased interest (again) as I’ve been receiving quite a few messages from new readers asking where to find spy numbers and what type of shortwave radio is needed. Truth is, there are fewer and fewer numbers stations still on the air, though some are still quite reliable (like HM01).

The following article by Shane Harris at The Daily Beast is one of the better, more detailed, articles I’ve read in the popular press.

(Source: The Daily Beast via Southgate ARC)

The Stupidly Simple Spy Messages No Computer Could Decode

by Shane Harris

When I was 10 years old, I found a shortwave radio in a crumbling old leather trunk where we kept family photos and other memorabilia.

As I spun the dial, tinny, modulating noises, like the song of an electronic slide whistle, emanated from the radio’s small speaker. Staticky cracks and pops competed for airtime. The sounds swished and swirled, unintelligible and unremarkable. But then, emerging through the clamor, was a voice.

I might have run right over it with the dial, but the voice’s rhythmic, steady pacing caught me up short. It wasn’t a deejay. Nor a commercial. And he wasn’t singing. He was just speaking. The same line, over and over again.

“7…6…7…4…3.” Pause. “7…6…7…4…3.”

I don’t remember if those were the exact numbers. But they were numbers. A repeated sequence which had no obvious meaning, and was entirely devoid of context. To find him here, amidst the screeches and howls of the shortwave frequencies, was like coming upon a man standing in the middle of a forest, talking out loud to no one.

How long had he been here? Who was he talking to? He had that officious tone of the recorded telephone operators who chastised you for dialing a wrong number. “Please hang up, check the number, and dial again.” And the same distracting static I’d heard in those messages filled the background. I wasn’t sure if he was speaking live, or if he’d been recorded and set loose to play into the air.

But there was an urgency to his tone. And a purpose. As if he were talking to me. Imploring. Listen. Hear me now. 7…6…7…4…3. Did you get that? 7…6…7…4…3.

I was simultaneously terrified and captivated.[…]

Continue reading at The Daily Beast…

Numbers Stations: A bad day to be a Cuban spy

SWLingPost-Spy-Numbers-Station

While band scanning last Sunday (September 8, 2014) I stumbled upon the Cuban numbers station HM01 on 11,530 kHz at 17:30 UTC.

It’s always intriguing to hear shortwave numbers stations, but I prefer those that stick to pure vocal number strings; HM01 has numbers with digital bursts between number sets, which is a more fatiguing listening experience.  Nonetheless, I kept it playing in the background as I tooled around the radio room Sunday afternoon, putting away supplies from my recent three week road trip.

WFL_015Several times during the HM01 broadcast, I heard the audio (not the AM carrier) drop in the middle of numbers sets and digital bursts. This isn’t the first time I’ve heard hiccups on HM01 (see this post from last year, for example), so I wasn’t terribly surprised. Then, close to the top of the hour, HM01 audio dropped for a minute or so, then switched back to five-number sets with no digital bursts between; though I wasn’t copying the message, I suspected that someone in the studio intentionally, perhaps in frustration–or else accidentally–started the broadcast from the beginning again.

At this point, I started recording. The five-number sets continue for about a minute, then the carrier unexpectedly drops:

Since it was near the top of the hour, and HM01 broadcasts only tend to last one hour, I didn’t expect to hear the broadcast repeat–and it didn’t, at least on 11,530.

Via a little band scanning, I discovered that HM01 had unexpectedly migrated 105 kHz higher, to 11,635 kHz. This broadcast audio also begins a little awkwardly. You’ll hear the audio drop; I scan for a few seconds,  then return to 11,635, and HM01 comes back. And this time, the numbers set sounds cleaner, with fewer problems. Here’s the recording:

I couldn’t help but chuckle over this…

Evidently, this message had some important content–otherwise they wouldn’t have re-broadcast the entire set the following hour, 105 kHz up from the original frequency (most likely protocol after technical difficulties). I imagine spies huddled around their radios, cursing at the interruptions and frustrated they had to listen for an additional hour; and I imagine the confusion at the broadcast site as they tried to diagnose the problem in a live broadcast. It’s during these little mistakes that numbers stations inadvertently tell us who they are (Radio Havana Cuba content has accidentally been played before on Cuban numbers stations).

Miami Herald: Cuban spies and shortwave numbers

towersI should note that we have several recordings and frequencies for the numbers station HM01, which is mentioned in this article. Very happy to see that they interviewed Chris Smolinski:

(Source: Miami Herald)

Even if you’re not a Cuban spy, you too can receive secret messages sent by Havana to its spooks in Miami, Washington and around the world.

Every week, one short wave radio station in Cuba broadcasts 97 messages coded in fax-like tones. A computer program easily available to the public changes the tones into numbers, and the Cuban spies then decode the numbers into words.

A second Cuban spy station transmits 16 messages per week in the dots and dashes of the 175-year-old Morse code – secret messages to Havana spies who may be older or less technologically savvy.

[…]The busiest Cuban station these days, and the only spy station in the world that uses the fax-like tones, has been baptized as HM01 by amateur eavesdroppers who run Web pages like Spooks List, Spynumbers, ShortwaveSchedule and Enigma2000.

It transmits 11 to 14 messages per day, a total of 96 per week, on the same schedule each week but using a dozen different short wave frequencies, said Chris Smolinski, 41, a Maryland software engineer who monitors the spy stations as a hobby.

Each message almost always has 150 five-digit groups, so that eavesdroppers cannot measure the true length of the text. And some of the 10-minute transmissions are phonies, designed to mask the real number of spies receiving them.

Anyone can hook up a radio receiver to a computer, where the DIGTRX program – widely used by ham radio aficionados to send and receive lengthy texts, turns the tones into numbers. Spies then use secret computer programs to turn numbers into text.

“HM01 is an ideal system because you don’t have to teach any to anybody. The computer does all the work,” said Smolinski.

For the less computer-savvy spooks there’s the M08a station, which broadcasts 16 messages in Morse code, developed for the telegraph in 1836, on a set weekly schedule and on many of the same frequencies as Hm01.

Read the full article on The Miami Herald website…

Numbers station HM01…and Ana Montes

Downloads-001Wednesday morning, I suppose I had number stations on the brain.  It was no surprise, as I had just watched The Numbers Station the previous night.  Nonetheless, I experienced a rather strange coincidence:  I was reading an intriguing article about Ana Montes, “one of the most damaging spies in U.S. history,” when my shortwave radio–parked on 5,855 kHz–suddenly began to fire out an eerie series of numbers and data bursts from the Cuban numbers station, HM01.  It was, unquestionably, the perfect accompaniment to the words I was reading.

A reader sent Montes’ story–written by Jim Popkin for The Washington Post Magazine–which made for fascinating reading. And as I read the account of Ana Montes’ rise in the ranks of the DIA, while simultaneously becoming one of Cuba’s most important spies, I remembered that it was actually Montes’ case that reader Dirk Rijmenants’ referred to in his paper, and that we posted earlier this year.

A "cheat sheet" provided by Cuban intelligence that Ana Montes used to help her encrypt and decrypt messages to and from her handlers. (Source: FBI)

A “cheat sheet” provided by Cuban intelligence that
Ana Montes used to help her encrypt and decrypt
messages to and from her handlers. (Source: FBI)

Popkin’s account of Ana Montes’ life, character, promotions within the Defense and Intelligence Agency, and the sequence of events that led to her FBI investigation and imprisonment, are the stuff of spy novels. And of course, he  mentions numbers stations:

[Montes’] tradecraft was classic. In Havana, agents with the Cuban intelligence service taught Montes how to slip packages to agents innocuously, how to communicate safely in code and how to disappear if needed.[…]

Montes got most of her orders the same way spies have since the Cold War: through numeric messages transmitted anonymously over shortwave radio. She would tune a Sony radio to AM frequency 7887 kHz, then wait for the “numbers station” broadcast to begin. A female voice would cut through the otherworldly static, declaring, “Atención! Atención!” then spew out 150 numbers into the night. “Tres-cero-uno-cero-siete, dos-cuatro-seis-dos-cuatro,” the voice would drone. Montes would key the digits into her computer, and a Cuban-installed decryption program would convert the numbers into Spanish-language text.[…]

On a side note, as Rijmenants points out, using a computer to decipher a numbers station was both unnecessary and risky.

The story continues:

Ana Montes

Ana Montes

[…]On May 25, 2001, [an FBI team] slipped inside Apartment 20. Montes was out of town with Corneretto [her boyfriend], and the FBI searched her closets and laundry bins, paged through shelves of neatly stacked books and photographed personal papers. They spotted a cardboard box in the bedroom and carefully opened it. Inside was a Sony shortwave radio. Good start, Lapp thought. Next, techs found a Toshiba laptop. They copied the hard drive, shut down the computer and were gone.[…]The documents, which Montes had tried to delete, included instructions on how to translate numbers-station broadcasts and other Spy 101 tips.[…][…]Later that day, an FBI evidence team scoured Montes’s apartment for hours. Hidden in the lining of a notebook they found the handwritten cipher Montes used to encrypt and decrypt messages, scribbled shortwave radio frequencies and the address of a museum in Puerto Vallarta, Mexico, where she was meant to run in an emergency. The crib sheets were written on water-soluble disappearing paper.[…]

The story Popkin recounts, though, paints the picture of a very complex operative. One who, until discovered, was very successful at her craft.  She pulled the wool over the eyes of the DIA and spied for the Cuban government for many years.

The story is complex, and Popkins’ account somehow maneuvers through the twists and turns.

If you want to experience what I did–if a little less coincidentally–click here to read Popkin’s full article, and meanwhile play this recording I made of the Cuban numbers station HM01, below:

Note that the year Montes listened to the Cuban numbers station on 7,887 kHz, it only contained numbers–unlike the recording here of HM01 (Hybrid Mode 01) which contains both voice and RDFT data bursts (which you can also decode, but not necessarily decipher).

This recording of the Cuban numbers station HM01 was recorded on April 24, 2013, at 10:00 UTC on 5,855 kHz in AM. Click here to download the recording as an MP3.

Again, click here to read Jim Popkin’s full story of Ana Montes on The Washington Post Magazine website.

Rijmenants’ paper sheds light on Cuban numbers stations

WFL_015I’m always amazed by the remarkable talents and extraordinary knowledge of SWLing Post readers. Dirk Rijmenants recently commented on one of our Cuban spy numbers station postings:

[T]hanks for your work on this fascinating blog.

I have additional information on how and who used these Cuban numbers stations. I composed a paper based on FBI and court documents. “Cuban Agent Communications” can by found in the Papers section of my website.

Here’s the direct link (pdf):
http://users.telenet.be/d.rijmenants/papers/cuban_agent_communications.pdf

Have fun reading!

Dirk Rijmenants
Cipher Machines & Cryptology

I’ve read Dirk’s paper, which does, indeed, shed light on the process of receiving and decoding numbers. Most of all, it exposes the vulnerability and fallacy of using anything other than one-time decryption keys and single-use pads. Why? Most of what the FBI has learned about Cuban numbers came from laptops that were used to help decrypt coded messages–an unnecessary procedure when numbers can simply be decoded on note pads that can then be burnt or destroyed.

But don’t take my word for it–download and read Dirk’s paper Cuban Agent Communications” by clicking here. Also, be sure to check out Dirk’s blog and cryptology website; I’ve bookmarked both.

Thanks for sharing your findings, Dirk!