Number stations are shortwave transmissions used by foreign intelligence agencies to send encrypted messages to spies in foreign countries. These transmissions use groups of numbers or letters and can be in the form of automated voice, Morse code, or digital modes. The encryption methods used by most number stations are unknown, but some are believed to use one-time pad encryption. Very few government organizations have released information about number stations, but they have been involved in publicly prosecuted espionage cases. Number stations offer anonymity to the recipients of the messages, as they can receive instructions without being traced through phone calls or internet connections. The ENIGMA naming system categorizes number stations based on language or signal type.
| Signal | Change | 10y horizon | Driving force |
|---|---|---|---|
| Number Stations | Shift from traditional espionage methods | Increased use of encrypted messages | Anonymity and security |
| ENIGMA naming system | Standardization of reporting number stations | Improved classification of stations | Improved information sharing |
| Decrease in number stations | Reduction in number of operational stations | Potentially fewer number stations | Advancements in communication technology |
| Increase in number station activity | Increase in operational number stations | More active use of number stations | Potential geopolitical changes |