|Number Stations - Spy Networks
Mysterious Radio Stations that Broadcast Numbers and Codes 24/7
Art or espionage? Mysterious radio stations broadcast
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
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
According to this theory, the messages are encrypted
with a one-time pad, to avoid any risk of decryption by the enemy.
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.
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.
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".
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
The message says:
101 118 105 100 101 110 116 32 97 103 101 110 100 97
which translating from the ASCII table becomes:
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
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
The federal prosecutors stated: "Montes communicated with the Cuban
Intelligence Service through encrypted messages and received her
instructions through encrypted shortwave transmissions from Cuba”.
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
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.
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
|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
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
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
Some stations send more than one message during a transmission. In this
case, some or all of the above process is repeated, with different
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
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.