In cryptography, the one-time pad (OTP) is an encryption technique that cannot be cracked, but requires the use of a single-use pre-shared key that is larger than or equal to the size of the message being sent. In this technique, a plaintext is paired with a random secret key. Then, each bit or character of the plaintext is encrypted by combining it with the corresponding bit or character from the pad using modular addition.
Signals intelligence (SIGINT) is the act and field of intelligence-gathering by interception of signals, whether communications between people or from electronic signals not directly used in communication. Signals intelligence is a subset of intelligence collection management. As classified and sensitive information is usually encrypted, signals intelligence may necessarily involve cryptanalysis. Traffic analysis—the study of who is signaling to whom and in what quantity—is also used to integrate information, and it may complement cryptanalysis.
MI8, or Military Intelligence, Section 8 was a British Military Intelligence group responsible for signals intelligence and was created in 1914. It originally consisted of four sections: MI8(a), which dealt with wireless policy; MI8(b), based at the General Post Office, dealt with commercial and trade cables; MI8(c) dealt with the distribution of intelligence derived from censorship; and MI8(d), which liaised with the cable companies. During World War I MI8 officers were posted to the cable terminals at Poldhu Point and Mullion in Cornwall and Clifden in County Galway, continued until 1917 when the work was taken over by the Admiralty. In WW2, MI8 was responsible for the extensive War Office Y Group and briefly, for the Radio Security Service.
International broadcasting, in a limited extent, began during World War I, when German and British stations broadcast press communiqués using Morse code. With the severing of Germany's undersea cables, the wireless telegraph station in Nauen was the country's sole means of long-distance communication.
A numbers station is a shortwave radio station characterized by broadcasts of formatted numbers, which are believed to be addressed to intelligence officers operating in foreign countries. Most identified stations use speech synthesis to vocalize numbers, although digital modes such as phase-shift keying and frequency-shift keying, as well as Morse code transmissions, are not uncommon. Most stations have set time schedules, or schedule patterns; however, some appear to have no discernible pattern and broadcast at random times. Stations may have set frequencies in the high-frequency band.
CHU is the call sign of a shortwave time signal radio station operated by the Institute for National Measurement Standards of the National Research Council. CHU's signal is used for continuous dissemination of official Canadian government time signals, derived from atomic clocks.
Radio Havana Cuba is the official government-run international broadcasting station of Cuba. It can be heard in many parts of the world, including the United States, on shortwave frequencies. Radio Havana Cuba, along with Radio Rebelde, Cubavision Television, and other Cuban radio and television, broadcasts to North, Central and South America via free-to-air programming from the Hispasat 30W-6 satellite over the Atlantic Ocean and worldwide via Internet streaming.
The Cipher Bureau was the interwar Polish General Staff's Second Department's unit charged with SIGINT and both cryptography and cryptanalysis.
Radio Moscow, also known as Radio Moscow World Service, was the official international broadcasting station of the Union of Soviet Socialist Republics until 1993, when it was reorganized into Voice of Russia, which was subsequently reorganized and renamed into Radio Sputnik in 2014. At its peak, Radio Moscow broadcast in over 70 languages using transmitters in the Soviet Union, Eastern Europe, and Cuba.
The United Kingdom – United States of America Agreement is a multilateral agreement for cooperation in signals intelligence between Australia, Canada, New Zealand, the United Kingdom, and the United States. The alliance of intelligence operations is also known as the Five Eyes. In classification markings this is abbreviated as FVEY, with the individual countries being abbreviated as AUS, CAN, NZL, GBR, and USA, respectively.
A secret broadcast is, simply put, a broadcast that is not for the consumption of the general public. The invention of the wireless was initially greeted as a boon by armies and navies. Units could now be coordinated by nearly instant communications. An adversary could glean valuable and sometimes decisive intelligence from intercepted radio signals:
Shortwave listening, or SWLing, is the hobby of listening to shortwave radio broadcasts located on frequencies between 1700 kHz and 30 MHz (30 000 kHz). Listeners range from casual users seeking international news and entertainment programming, to hobbyists immersed in the technical aspects of long-distance radio reception and sending and collecting official confirmations that document their reception of remote broadcasts (DXing). In some developing countries, shortwave listening enables remote communities to obtain regional programming traditionally provided by local medium wave AM broadcasters. In 2002, the number of households that were capable of shortwave listening was estimated to be in the hundreds of millions.
Radio jamming is the deliberate blocking of or interference with wireless communications. In some cases, jammers work by the transmission of radio signals that disrupt telecommunications by decreasing the signal-to-noise ratio.
Tradecraft, within the intelligence community, refers to the techniques, methods, and technologies used in modern espionage (spying) and generally as part of the activity of intelligence assessment. This includes general topics or techniques, or the specific techniques of a nation or organization.
The Lincolnshire Poacher was a powerful British shortwave numbers station that transmitted from HM Government Communications Centre near Gawcott in Buckinghamshire, England, and later from Cyprus, from the mid-1960s to June 2008. The station gained its commonly known name as it uses bars from the English folk song "The Lincolnshire Poacher" as an interval signal. The radio station was believed to be operated by the British Secret Intelligence Service. Amateur direction finding linked it with the Royal Air Force base at Akrotiri, Cyprus, where several curtain antennas were identified as being its transmitter. It consisted of a pre-recorded English-accented female voice reading groups of five numbers: e.g., '0-2-5-8-8'. The final number in each group was spoken at a higher pitch. It is likely that the station was used to communicate to undercover agents operating in other countries, to be decoded using a one-time pad.
UVB-76, also known by the nickname "The Buzzer", is a shortwave radio station that broadcasts on the frequency of 4,625 kHz. It broadcasts a short, monotonous, repeating at a rate of approximately 25 tones per minute, 24 hours per day. Sometimes, the buzzer signal is interrupted and a voice transmission in Russian takes place.
Swedish Rhapsody No. 1 is the subtitle of Midsommarvaka, a symphonic rhapsody by the Swedish composer Hugo Alfvén (1872–1960). Although it is only the first of three similarly named works, it is often simply called "the Swedish Rhapsody".
The Pip is a shortwave radio station that broadcasts on the frequency 5448 kHz by day, and 3756 kHz during the night. It broadcasts short, repeated beeps at a rate of around 50 per minute, for 24 hours per day. The beep signal is occasionally interrupted by voice messages in Russian. The Pip has been active since 1986, when its distinctive beeping sound was first recorded by listeners, and is a sister station to UVB-76.
The Tyrolean Music Station was a believed French shortwave numbers station that transmitted from Chartres in the Centre-Val de Loire region, France, from the early 1970s until late 1975. The station played several folk music songs by German yodeller Franzl Lang, prior to broadcasting one or several coded messages, and a music-box rendition of "The Internationale". The station was of unknown origin during the time it was broadcasting, until a French magazine, Interférences, claimed in their Autumn 1975 issue that the station was operated by the French intelligence service, SDECE. Shortly after this magazine was published, the station ceased broadcasting.
The Gongs or Chimes was a German shortwave numbers station that transmitted from Zeesen in the Brandenburg region of East Germany, between the early 1970s until 9 May 1990. The station would broadcast one or several coded messages daily during its operational life, with the messages being read out using an East German "Sprach-Morse Generator".
