Numbers Stations

Encryption

Number stations employ the one-time pad encryption method, a virtually unbreakable system due to its randomness. Gary Arndt explains that this method requires both the sender and receiver to have a shared key, allowing them to decode messages without others understanding them 1. This technique is favored by intelligence agencies for its security, as it allows messages to be broadcast publicly without revealing their content.

A shortwave radio transmission can be picked up literally anywhere. All that's required to pick up the signal is a cheap shortwave radio, which can be purchased almost anywhere.

--- Gary Arndt

Despite the public nature of these broadcasts, the use of shortwave radio ensures that the intended recipient can receive the message discreetly 2.

   

Broadcasting

Shortwave radio is the medium of choice for number stations due to its ability to transmit signals over vast distances. Gary Arndt notes that these signals can bounce between the ionosphere and the Earth's surface, allowing them to cover great distances, unlike FM radio signals which are limited by the horizon 3. This characteristic makes shortwave ideal for covert communication, as it can reach agents anywhere in the world.

Shortwave radio signals can travel long distances due to their ability to reflect off the ionosphere.

--- Gary Arndt

During the Cold War, the use of shortwave radio for number stations proliferated, with each station adopting unique identifiers like songs or sound clips to distinguish themselves 3.