Why capturing an airborne radio compatible with NATO’s Link-16 tactical datalink protocol may not hand Russian radio frequency engineers an intelligence coup.
In late November, Pravda cited a Turkish source which stated that Ukraine’s Ministry of Defence had requested access to North Atlantic Treaty Organisation (NATO) Link-16 connectivity. Link-16 is a secure, encrypted tactical voice and communications protocol. Primarily used to support air operations, Link-16 traffic includes target track data and other tactically relevant information. This traffic is carried via so-called ‘J-Series’ messages across frequencies of 960 megahertz to 1.215 gigahertz. NATO began to use Link-16 in the 1980s and the protocol has supported alliance air operations ever since.
The Pravda article speculated that furnishing the Ukrainian F-16s with Link-16 could allow these aircraft to plug into NATO Link-16 networks. Open-source websites like flightradar24 regularly show NATO aircraft flying in alliance airspace close to Ukraine’s borders. These planes can include Boeing RC-135V/W Rivet Joint Signals Intelligence (SIGINT) aircraft flown by the United States Air Force and the Royal Air Force. Regular flights are also made by alliance airborne early warning and control aircraft such as Boeing E-3 series jets or Royal Swedish Air Force Bombardier/Saab S106 GlobalEye platforms. These NATO planes can all carry Link-16 compatible radios. The article speculated that Ukrainian F-16s could now receive tactical information direct from NATO aircraft via Link-16 networks. Technically, this is possible. Whether it has occurred is beyond the scope of this article.
Does Russian have Link-16 technology?
Pravda’s boldest assertion was that “if Russia obtains … the Link-16 system, it may have an extremely negative impact on the combat capability of NATO aviation.” The article surmised that the Russian military may succeed in shooting down an F-16, or a Ukrainian F-16 pilot could be tempted to defect. A Link-16 compatible radio in the possession of Russian engineers might then give up its secrets. The article warns that “(i)f this equipment falls into the hands of Russian specialists, they will be able to access NATO codes and ciphers used in the system.”
It is difficult to believe that Russia does not already have knowledge of Link-16 technology. NATO nations have lost several combat aircraft over the years that were likely equipped with Link-16 compatible radios. Many of these aircraft have been downed by countries, or organisations, considered sympathetic to Russia. During NATO operations in the Balkans in the 1990s three alliance combat aircraft were shot down by the Bosnian Serb Army and/or the Yugoslav military.
Famously, a US Navy Lockheed Martin EP-3E Aries-II SIGINT aircraft was forced to land on Hainan Island off the southern coast of the People’s Republic of China on 1st April 2001. The EP-3E landed after a collision with a People’s Liberation Army (PLA) Navy Air Force Shenyang J-8 (NATO reporting name Finback) series combat aircraft. The EP-3E crew were released after ten days of internment on the island. The aircraft was disassembled and later returned to the US Navy on 3rd July 2001. Reports revealed that the PLA examining the EP-3E captured cryptographic keys used by the aircraft’s communications. It was speculated that some classified materials the EP-3E crew could not destroy were shared with Russia.
Robust encryption
Capturing a Link-16 compatible radio is unlikely to result in an intelligence coup rendering the protocol redundant overnight. Open sources say that Link-16 J-Series messages, and the signal carrying this traffic, are encrypted. To break into a Link-16 network both the message, and the signal, must be decrypted. Moreover, Link-16 networks use pseudo-random frequency-hopping. Each separate Link-16 network has its own distinct frequency-hopping scheme. Link-16 messages and traffic can only be encrypted or decrypted using the message and traffic encryption keys embedded in the radios at that time. Keys are regularly changed precisely to frustrate any attempts to gain unauthorised access to a Link-16 network. A Link-16 compatible radio could be captured, and its encryption keys discovered, but it is unlikely the keys will have any use. By the time the radio can be used to gain illicit access to Link-16 traffic, encryption keys will have changed. Even if Russian engineers do succeed in capturing a Link-16 radio, they may find it little more than dead circuitry as far as secure Link-16 traffic is concerned.
by Dr. Thomas Withington
