Number Stations
Mysterious Radio Stations that Broadcast Numbers and Codes 24/7

 

 

 
Number Stations - Spy Networks
Mysterious Radio Stations that Broadcast Numbers and Codes 24/7

Art or espionage? Mysterious radio stations broadcast numbers and codes 24/7. Who are they and what does it mean? We investigate the cold-war era phenomena. Conspiracy theorists will love this, show it to your paranoid friends today!


Number Stations have been around since the cold-war. They are basically shortwave broadcasts of a series of numbers. These number stations do not have any call letters since for all intentions they don't exist.

The numbers can be coming from a human female or male voice and sometimes from a computer. These numbers are broadcast in many different languages throughout the world.

Many believe they are used as a form of communication for spies, terrorists, drug dealers and members of the CIA and other organizations that are not known. This type of code is used only once. The numbers represent letters or words from a one time encryption.


In cryptography, the one-time pad (OTP) is a type of encryption, which has been proven to be impossible to crack if used correctly. Each bit or character from the plaintext is encrypted by a modular addition with a bit or character from a secret random key (or pad) of the same length as the plaintext, resulting in a ciphertext.

If the key is truly random, as large as the plaintext, never reused in whole or part, and kept secret, the ciphertext will be impossible to decrypt or break without knowing the key. It has also been proven that any cipher with the perfect secrecy property must use keys with effectively the same requirements as OTP keys. However, practical problems have prevented one-time pads from being widely used.


According to the notes of The Conet Project, numbers stations have been reported since World War I. If accurate, this would make numbers stations among the earliest radio broadcasts.

It has long been speculated, and was argued in court in one case, that these stations operate as a simple and foolproof method for government agencies to communicate with spies working undercover.

According to this theory, the messages are encrypted with a one-time pad, to avoid any risk of decryption by the enemy.

As evidence, numbers stations have changed details of their broadcasts or produced special, nonscheduled broadcasts coincident with extraordinary political events, such as the August Coup of 1991 in the Soviet Union.

Number Stations are also acknowledged for espionage purposes in Robert Wallace and H. Keith Melton's Spycraft: The one-way voice link (OWVL) described a covert communications system that transmitted messages to an agent's unmodified shortwave radio using the high-frequency shortwave bands between 3 and 30 MHz at a predetermined time, date, and frequency contained in their communications plan.

The transmissions were contained in a series of repeated random number sequences and could only be deciphered using the agent's one-time pad.

If proper tradecraft was practiced and instructions were precisely followed, an OWVL transmission was considered unbreakable.

As long as the agent's cover could justify possessing a shortwave radio and he was not under technical surveillance, high-frequency OWVL was a secure and preferred system for the CIA during the Cold War.

Others speculate that some of these stations may be related to illegal drug smuggling operations. Unlike government stations, smugglers' stations would need to be lower powered and irregularly operated, to avoid location by triangulated direction finding, followed by government raids.

However, numbers stations have transmitted with impunity for decades, so they are generally presumed to be operated or sponsored only by governments.

Also, numbers station transmissions in the international shortwave bands typically require high levels of electric power that is unavailable to ranches, farms, or plantations in isolated drug-growing regions.
 
 
The Conet Project: Recordings of Shortwave Numbers Stations is a four-CD set of recordings of numbers stations, mysterious shortwave radio stations of uncertain origin believed to be operated by government agencies to communicate with spies "in the field".

The collection was released by England's Irdial-Discs record label in 1997, based on the work of numbers station enthusiast Akin Fernandez.





Number Station VII [Achtung!]

Number stations are shortwave radio stations of uncertain origin. They generally broadcast artificially generated voices reading streams of numbers, words, letters (sometimes using a spelling alphabet), tunes or Morse code.

They are in a wide variety of languages and the voices are usually women's, though sometimes men's or children's voices are used.


High frequency radio signals transmitted at relatively low power can travel around the world under ideal propagation conditions, which are affected by local RF noise levels, weather, season, and sunspots, and can then be received with a properly tuned antenna of adequate size, and a good receiver.

However, spies often have to work only with available hand held receivers, sometimes under difficult local conditions, and in all seasons and sunspot cycles.

Only very large transmitters, perhaps up to 500,000 watts, are guaranteed to get through to nearly any basement-dwelling spy, nearly any place on earth, nearly all of the time.

Some governments may not need a numbers station with global coverage if they only send spies to nearby countries. Although no broadcaster or government has acknowledged transmitting the numbers, a 1998 article in The Daily Telegraph quoted a spokesperson for the Department of Trade and Industry (the government department that, at that time, regulated radio broadcasting in the United Kingdom) as saying, "These [numbers stations] are what you suppose they are. People shouldn't be mystified by them. They are not for, shall we say, public consumption."

On some stations, tones can be heard in the background. It has been suggested that in such cases the voice may be an aid to tuning to the correct frequency, with the coded message being sent by modulating the tones, perhaps using a technology such as burst transmission.

The use of number stations as a method of espionage is discussed in Spycraft: The only item Penkovsky used that could properly be called advanced tradecraft was his 'agent-receive' communications through a one-way voice-link. These encoded messages, known as OWVL, were broadcast over shortwave frequencies at predetermined times from a CIA-operated transmitter in Western Europe.

Penkovsky listened to these messages on a Panasonic radio — strings of numbers read in a dispassionate voice — and then decoded them using a one-time pad.

Number Stations

The message says:

101 118 105 100 101 110 116 32 97 103 101 110 100 97
(twice)

which translating from the ASCII table becomes:
"evident agenda"



Numbers stations (or number stations) are shortwave radio stations of uncertain origin. They generally broadcast artificially generated voices reading streams of numbers, words, letters (sometimes using a spelling alphabet), tunes or Morse code.

They are in a wide variety of languages and the voices are usually female, though sometimes male or children's voices are used.


Evidence supports popular assumptions that the broadcasts are used to send messages to spies. This usage has not been publicly acknowledged by any government that may operate a numbers station, but in 2001, the United States tried the Cuban Five for spying for Cuba.

The group had received and decoded messages that had been broadcast from a Cuban numbers station. Also in 2001, Ana Belen Montes, a senior US Defense Intelligence Agency analyst, was arrested and charged with espionage.

The federal prosecutors stated: "Montes communicated with the Cuban Intelligence Service through encrypted messages and received her instructions through encrypted shortwave transmissions from Cuba”.

Number Stations

Numbers stations are shortwave radio stations of uncertain origin. They generally broadcast voices reading streams of numbers, words, letters (sometimes using a radio alphabet), tunes or Morse code.

This is a collaborative piece with Ben Walker as part of the Contextual Villains Collaborative.


The audio track is compiled from two samples of number station broadcasts. One layer is of a woman sounding out numbers at random in Polish, another of a man speaking Russian.

In 2006, Carlos Alvarez and his wife Elsa Alvarez were arrested and charged with espionage. The U.S. District Court Florida stated: "defendants would receive assignments via shortwave radio transmissions”.

In June 2009, the United States similarly charged Walter Kendall Myers with conspiracy to spy for Cuba and receiving and decoding messages broadcast from a numbers station operated by the Cuban Intelligence Service to further that conspiracy.

It has been reported that the United States uses numbers stations to communicate encoded information to persons in other countries. Numbers stations appear and disappear over time (although some follow regular schedules), and their overall activity has increased slightly since the early 1990s. This increase suggests that, as spy-related phenomena, they were not unique to the Cold War.


One-Time Pad (OTP)

In cryptography, a one-time pad is a system in which a private key generated randomly is used only once to encrypt a message that is then decrypted by the receiver using a matching one-time pad and key.


In cryptography, the one-time pad (OTP) is a type of encryption, which has been proven to be impossible to crack if used correctly. Each bit or character from the plaintext is encrypted by a modular addition with a bit or character from a secret random key (or pad) of the same length as the plaintext, resulting in a ciphertext.

If the key is truly random, as large as or greater than the plaintext, never reused in whole or part, and kept secret, the ciphertext will be impossible to decrypt or break without knowing the key. It has also been proven that any cipher with the perfect secrecy property must use keys with effectively the same requirements as OTP keys.

However, practical problems have prevented one-time pads from being widely used. The one-time pad was invented in 1917 and patented a couple of years later.

 
Messages encrypted with keys based on randomness have the advantage that there is theoretically no way to "break the code" by analyzing a succession of messages.

It is derived from the Vernam cipher, named after Gilbert Vernam, one of its inventors. Vernam's system was a cipher that combined a message with a key read from a paper tape loop. 

In its original form, Vernam's system was not unbreakable because the key could be reused. One-time use came a little later when Joseph Mauborgne recognized that if the key tape were totally random, cryptanalytic difficulty would be increased.

The "pad" part of the name comes from early implementations where the key material was distributed as a pad of paper, so the top sheet could be easily torn off and destroyed after use. For easy concealment, the pad was sometimes reduced to such a small size that a powerful magnifying glass was required to use it.

Photos accessible on the Internet show captured KGB pads that fit in the palm of one's hand, or in a walnut shell. To increase security, one-time pads were sometimes printed onto sheets of highly flammable nitrocellulose.



Number Stations - Transmission Technology

Although few numbers stations have been tracked down by location, the technology used to transmit the numbers has historically been clear — stock shortwave transmitters using powers from 10 kW to 100 kW.

Amplitude modulated (AM) transmitters with optionally variable frequency, using class-C power output stages with plate modulation, are the workhorses of international shortwave broadcasting, including numbers stations.

Application of spectrum analysis to number station signals has revealed the presence of data bursts, RTTY-modulated subcarriers, phase-shifted carriers, and other unusual transmitter modulations like polytones. (RTTY-modulated subcarriers were also present on some U.S. commercial radio transmissions during the Cold War.)

The frequently reported use of high tech modulations like data bursts, in combination or sequence with spoken numbers, suggest transmissions for differing intelligence operations.

Speech/Morse generatorFor spies in the field, low tech spoken number transmissions continue to have advantages in the 21st century. High tech data receiving equipment is difficult to obtain, and being caught with more than a civilian shortwave news radio could be construed as evidence of spying.

Yet governments' embassies, aircraft, and ships at sea are known to possess complex receiving equipment that could make regular use of encrypted data transmissions from the home country. These probably include charts and photos that require more transmitted data than can be sent efficiently using spoken numbers. 


Generally, numbers stations follow a basic format, although there are many differences in details between stations. Transmissions usually begin on the hour or half-hour.

The prelude or introduction of a transmission (from which stations' informal nicknames are often derived) includes some kind of identifier, either for the station itself and/or for the intended recipient.


This can take the form of numeric or radio-alphabet "code names" (e.g. "Charlie India Oscar", "250 250 250"), characteristic phrases (e.g. "¡Atención!", "1234567890"), and sometimes musical or electronic sounds (e.g. "The Lincolnshire Poacher", "Magnetic Fields").

Sometimes, as in the case of the Israeli radio-alphabet stations, the prelude can also signify the nature or priority of the message to follow (e.g.(hypothetically) "Charlie India Oscar-2", indicating that no message follows). Often the prelude repeats for a period before the body of the message begins.

There is usually an announcement of the number of number-groups in the message, then the groups are recited. Groups are usually either four or five digits or radio-alphabet letters. The groups are typically repeated, either by reading each group twice, or by repeating the entire message as a whole.



Number Station Machines

Here's the actual machine behind the numbers station. This machine pronounces, in a monotone voice, a string of numbers used by intelligence agencies for one-way shortwave radio communication with their agents in enemy countries.

This machine belongs to a German collector who has a vast collection of various spy-gadgets. There were many machines of this particular model produced in East-Germany for usage within the DDR itself or other communist bloc nations, like the Soviet Union or Cuba.

The voice for this machine comes from a swapable printed circuit board with EEPROM's on it. In this video another board was inserted, which contained the Spanish voice samples, in the so-called Speech/morse generator, or "Sprach/morse generator", as it was referred to in Germany.

These EEPROMS enabled the machine to pronounce the numbers and other characters in Spanish or other languages depending on which card was inserted on the back of the machine.


Some stations send more than one message during a transmission. In this case, some or all of the above process is repeated, with different contents.


Finally, after all the messages have been sent, the station will sign off in some characteristic fashion. Usually it will simply be some form of the word "end" in whatever language the station uses (e.g. "end of message, end of transmission"; "Ende"; "fini"; "final"; "konets").

Some stations, especially those thought to originate from the former Soviet Union, end with a series of zeros, e.g. "000 000"; others end with music or other sundry sounds.

Because of the secretive nature of the messages, the cryptographic function employed by particular stations is not publicly known, except in one or possibly two cases.

It is assumed that most stations use a one-time pad that would make the contents of these number groups indistinguishable from randomly generated numbers or digits. In the one definitely known case, West Germany did use a one-time pad for numbers transmissions.
 
No government has ever acknowledged the existence of a number station. Once a British official said this: "People shouldn't be interested in number stations because they shouldn't be listening to them because they are illegal to listen to". In reality, shortwave is free for all to listen to and the number station itself is illegal, and not necessarily the listeners activities.