Unraveling the Enigma of Number Stations
The whispers of coded numbers and locations, uttered in monotonous voices on shortwave radio frequencies, have captivated listeners for decades. These enigmatic transmissions, known as number stations, have fueled speculation and theories about their origins and purpose.
Two groups of people listen to radio waves. The majority are ordinary individuals, tuning in to FM/AM or internet radio. A smaller group, known as "shortwave hunters," scour the high frequencies, including shortwave, very high frequency, and ultra-high frequency bands, often used for security communications and satellite signals.
These shortwave enthusiasts frequently intercept transmissions from international radio stations in countries like China, Cuba, Iran, and Romania, as well as maritime and aviation communication signals. Shortwave frequencies can travel vast distances, crossing continents, due to the reflective properties of the ionosphere.
Beyond typical news and entertainment broadcasts, shortwave hunters sometimes encounter enigmatic signals: monotonous voices reciting numbers, letters, or locations in seemingly random sequences. These messages are sometimes delivered in Morse code or digitally encrypted. This phenomenon is collectively referred to as number stations.
Examples of number stations discovered by YouTubers:
- "The Lincolnshire Poacher" - A famous number station that transmitted a musical tune before reciting numbers, believed to have been operated by British intelligence.
- "The Swiss Rhapsody" - Another well-known station that broadcast classical music followed by coded messages.
- "The Gongs" - A station recognized by its distinctive gong sound before delivering numbers.
These mysterious broadcasts have captivated journalists, game developers, and filmmakers, yet concrete explanations remain scarce. Often labelled as "creepy," "eerie," or "mysterious," the subject often stops there.
While some may hope for extraterrestrial contact or mind control devices, these number stations are not remnants of the Cold War, nor are they alien signals. Instead, they are integral parts of sophisticated communications used by intelligence agencies and militaries.
The Advantage of Number Stations
Cryptology, the science of encoding and decoding messages, has existed since the time of Caesar. Before radio, secret messages were transmitted via coded letters or light signals. The advent of radio in the early 20th century quickly found its way into military operations.
The first documented use of number stations dates back to World War I, when coded messages were sent via Morse code on low and medium-frequency bands. Shortwave radio, introduced in the 1920s, became a tool for sending encrypted messages. When directed at the ionosphere at an angle, shortwave signals bounce back to Earth, reaching far beyond the horizon, making it ideal for clandestine operations or for military commands to reach distant units.
However, the accessibility of these signals to the public meant that messages required encryption. Enter the One-time Pad (OTP).
OTP is considered the only mathematically unbreakable encryption system. It typically involves a sheet of paper containing random numbers in groups of five or more. Decoding an OTP requires two identical copies of the message, one held by the sender and one by the receiver. These pads are often small, easily concealed, or made of flammable materials for quick disposal after use.
The OTP encryption and decryption process is surprisingly simple but unbreakable due to its random nature. Here's a basic example:
- Each letter in the alphabet is assigned a number, for instance, A is 01, B is 02, C is 03, and so on.
- The sender writes the message and corresponding numbers in rows.
- Using a completely random set of numbers from the first OTP copy, the sender adds them to the message numbers. For instance, an OTP with numbers 72, 42, 57, 14... would yield a new random sequence (94, 47, 75...). If the result exceeds 100, only the last two digits are used. This sequence is then divided into groups of five and transmitted via the number station.
To decrypt, the receiver uses the second OTP copy with matching numbers. Instead of adding, they subtract to obtain the original message. These numbers are then translated back into letters based on the organization's initial alphabet. For example, 19 is S, 05 is E, and so on.
The effectiveness of OTP relies on a long, random number sequence, never reused, and available only to the sender and receiver.
This straightforward yet highly effective method ensures third parties can only decrypt the message if they access the receiver's OTP. This has sometimes been achieved through espionage, using double agents or capturing the receiver, particularly when intercepting signals. Numerous 20th-century events confirm the use of these signals by intelligence agencies.
Between 1945 and 1956, the CIA and British SIS recruited spies to support anti-Soviet resistance forces in the Baltic states, Belarus, and Ukraine. Many were captured with their radio transmitters and OTP books. The KGB used these codes to force captured spies to send false information to their headquarters. This was even portrayed in a 1988 KGB-produced TV series called "The Game."
In 1983, the KGB uncovered CIA spy Alexander Ogorodnik, a Soviet diplomat assigned to American radio stations. Another notable case was the "Cuban Five" in 2001, where Cuban spies were apprehended in the United States. Shortwave broadcasts were used as evidence against them. The spies received number messages via radio and entered them into a Toshiba laptop, where they were decrypted using a special floppy disk containing the decryption key.
In 2013, a German couple was put on trial for spying for Russia and divulging military secrets. They also received shortwave messages and were caught while receiving them.
Number Stations Today
Number station activity peaked around 1960, with channels like "The Lincolnshire Poacher," "The Swiss Rhapsody," and "The Gongs" broadcasting regularly. Following the fall of the Soviet Union, activity declined significantly, as numerous intelligence agencies that relied on number stations linked to the KGB, like the Stasi and Romanian Security Service, were dismantled.
Western intelligence agencies adopted new methods for encrypted message transmission, including steganography, which involves encoding messages in images or any digital media. Nevertheless, number station monitoring groups have revealed that the SVR, Russia's foreign intelligence service, continues to use this method extensively.
Other nations using number stations likely include North Korea. From 2000 to 2016, North Korea continued to broadcast encrypted messages directly from its state radio station, Radio Pyongyang, disguised as math or physics problems for "distant university students."
Not all number stations transmit in the native language, with foreign languages used as well. Notably, militaries utilize these channels for purposes beyond espionage. The well-known Russian "Buzzer" station was used by the Russian military internally to relay missions and orders to various Russian military units within the country. This can be partially explained by the fact that their stations send signals during the day, when the ionosphere's activity prevents these messages from reaching Western Europe and the United States effectively.
Listening to these stations is relatively easy. A shortwave radio is not strictly necessary, as software nowadays can identify and access them remotely via the internet. The accessibility of these receivers through software allows people worldwide to connect and operate them remotely, contributing to the active number station hunting community online.
Summary: Number stations, enigmatic broadcasts of coded numbers and locations, have intrigued listeners for decades. While often shrouded in mystery, these stations are not remnants of the Cold War or signals from extraterrestrials, but rather integral parts of sophisticated communication systems used by intelligence agencies and militaries. These coded messages, often transmitted using the One-time Pad encryption system, have played significant roles in espionage and military operations, with examples ranging from Cold War spies to modern-day espionage cases. Though the use of number stations may have declined with the advent of new digital technologies, they remain a fascinating and enduring aspect of the world of espionage. The ease of access to these transmissions through software has fostered an active online community of enthusiasts who continue to decode and analyze the mysteries of these enigmatic broadcasts.