Friend or foe: securing aircraft IFF systems

The US Air Force has contracted Raytheon to provide secure identification friend-or-foe (IFF) equipment in a bid to help safeguard aircraft. IFF technology, which helps radar operators and missile crews tell the difference between friendly and potentially hostile aircraft, can be susceptible to spoofing, so securing this capability is essential. Claire Apthorp takes a look at Raytheon’s solution and other approaches to keeping IFF equipment secure.


In July it was announced that US defence company Raytheon would provide the US Air Force with a $42.8 million follow on order of secure identification friend-or-foe (IFF) equipment as part of continuing efforts by the service to increase the security and surety of its IFF systems.

IFF is an important tool for air forces because it enables military and civilian air traffic control interrogation systems to identify aircraft, vehicles or forces as friendly and to determine their bearing and range from the interrogator.

It is particularly important in the age of supersonic aircraft and missiles that make it impossible to rely on visual identification methods; and without such systems modern command and control would almost be impossible. Ensuring the capability in an ever more complex battlespace is crucial.

"It is particularly important in the age of supersonic aircraft and missiles that make it impossible to rely on visual identification methods."

“The Identification Friend or Foe system is critical to the warfighter as it positively identifies friendly forces, reduces potential for fratricide and increases situation awareness,” says Frank Whiston, IFF director, Tactical Communications Systems, Raytheon Space and Airborne Systems (SAS).

In this case, the US Air Force contract was let by the Air Force Life Cycle Management Center at Joint-Base San Antonio, Texas and was for the provision of KIV-77 Mode 4/5 cryptographic applique systems by Raytheon SAS in Aberdeen, Maryland.

“The KIV-77 is the Mode 5 Crypto Applique device that provides the security function of the IFF system. This recent contract award was a follow-on IDIQ from USAF to provide KIV-77 Crypto Appliques to international and domestic operators,” explains Whiston.

The big spoof

The spoofing or mimicking of IFF technology by more sophisticated potential opponents was identified as a concern by the US Air Force as far back as the 1990s. The potentially disastrous consequences of a near peer competitor being able to spoof the then generation of IFF transponders was acknowledged, and advanced cryptography was seen as the best solution.

Devices such as the KIV-77 - which in essence allows the user to input a secure cryptographic key that is transmitted as part of the wider IFF transponder signal ensuring its authenticity to other users - were designed to overcome those concerns. Raytheon made the first deliveries of the device in 2010.

In today’s environment the major concerns for IFF are electronic interference and key loading (the secure distribution of the correct cryptographic keys). According to Raytheon these two areas are the most challenging issues for secure IFF.

“Raytheon has designed, developed and produced IFF systems for more than 60 years, and we were the first company to integrate Military Mode 4 with Civil Mode S to provide a fully integrated Traffic Collision Avoidance System,” Whiston states. “Raytheon is one of the core developers of the Mode 5 waveform including the development of Crypto Applique.”

NSA certified

The KIV-77 is Type 1 certified by the National Security Agency and provides information assurance for both legacy Mode 4 and new Mode 5 IFF equipment. Mode 5 IFF is the next-generation encrypted data link between interrogators and transponders to confirm an aircraft is friendly, and provides information assurance for MK XIIA IFF interrogators and transponders using Mode 4 and Mode 5.

Raytheon is considered a leader in IFF crypto, introducing new technologies that have significantly reduced size, weight and power dissipation while improving reliability. Its appliqué solutions offer all of these benefits while maintaining the crypto in a separate 3.5 inch x 4.25 inch x 1 inch, 16 ounce line replaceable unit allowing it to be removed and stored as security procedures dictate without disturbing the integrity of the host interrogator or transponder.

"In this way Raytheon argues that it futures proofs the system for the next generation of aircraft and missile technology."

“KIV-77 is NSA certified and incorporates all the new features of the Mode 5 system, providing reduced size, weight, and power consumption (SWaP) over the older Mode 4 system,” Whiston says. In this way Raytheon argues that it futures proofs the system for the next generation of aircraft and missile technology.

Where the US leads its allies usually follow and this has been illustrated in the UK by its adoption of the same protocols. In 2013 Raytheon UK and Thales UK announced that they had successfully conducted over-the-air Mode 5 Identification Friend or Foe (IFF) interoperability trials at Raytheon's Matching Green test range.

UK contracts

According to the companies, the trials in early December 2012 used Thales' TSA1412 Interrogator and Raytheon UK's IFF4810 Transponder, which is the standard fit SIFF (Successor IFF) product, featuring the Mode 5 enabled upgrade. Being more cryptographically secure than its predecessors, the Mode 5 system counters exploitation and deception while delivering resistance to Electronic Counter Measures (ECM). As in the US, the UK equipment was fitted with Raytheon SAS KIV-77 Mode 5 Cryptocomputers.

At the time, Richard Daniel, managing director, Raytheon UK's defence business, stated that, "Raytheon has invested in developing the Mode 5 upgrades for existing equipment, and Thales has Mode 5-qualified equipment already in service with French and other NATO armed forces. By teaming, we exploit the complementary strengths of both companies to minimise platform integration risks for Mode 5, and believe we offer the Ministry of Defence the best possible value for money. Together we would seek to ensure maximum continuity of operational availability by applying our already successful front-line support model during the transition to Mode 5."

However, Raytheon and Thales were unsuccessful in securing the UK work and in 2016 it was announced that Leonardo had been selected to provide the UK’s Mode 5 IFF needs. The company was awarded a £260 million contract in July of this year to equip some 350 units with Mode 5 IFF transponders ranging from the Royal Air Force’s Sentry aircraft to the Royal Navy’s Type 45 anti-air warfare destroyers and the British Army’s High Velocity Missile (HVM) multiple launcher system.

As forces like the US Air Force prepare to face a return to peer or near-peer adversaries, technologies such as IFF remain a key capability to allow them to dominate the battlefield. With companies such as Raytheon continuing to push the envelope in IFF technologies, the battle is already half won.