In the late 1980's, the KW-46 simplex cryptosystem was introduced in order to provide communications security (COMSEC) for naval broadcasts to naval fleets (Fleet Broadcast).  It replaced the old TSEC/KW-37 and TSEC/KG-14 cryptosystems. Formally, this equipment is called "Fleet Broadcast Security Equipment, TSEC/KW-46". The  KW-46 consists of the KWT-46 transmitter and the KWR-46 receiver (code name Vallor). The Royal Canadian Navy was a "customer" of this system.

The KWR-46 is a "low level" device that performs on-line decryption of digital messages, records, and data traffic received over the broadcast system at data rates from 50 to 9,600 bits per second in asynchronous, stepped or synchronous modes.  It uses a continuous synchronization pattern situated directly in the transmitted traffic and will process up to and including TOP SECRET information. The KWR-46 is used for over-the-air transfer (OTAT) of crytographic material to support KG-84A/C use. Also supported is the  North Atlantic Treaty Organization (NATO) Broadcast, the Navy Standard Teleprinter (NST), low frequency (LF) /high frequency (HF) R-2368 receiver equipment, and the High Speed Fleet Broadcast (HSFB). The KWR-46 is used on ships; the KWT-46 is located ashore.

Unkeyed KWR-46 equipment is classified CONFIDENTIAL. Keyed KWR-46 equipment assumes the classification level equal to that of the keying material but not less than confidential. Access to KWR-46 equipment is limited to personnel who possess a security clearance equal to the classification of the KWR-46 or its keying material, whichever is greater. Electronic key fill of the KWR-46 will only be accomplished through the utilization of the Key Tape Reader KOI-18/TSEC and AN/CYZ-10, DTD.

KWT-46(?) photo courtesy of U.S.N.

The KWR-46 uses the BA-1371/U mercury battery to provide for cryptovariable memory retention when the KWR-46 is turned off or the primary power source is removed. A lithium battery alternative is under development but was not yet approved in 1988).

The high reliability demonstrated by the KWR-46 allows a maintenance concept that concentrates all corrective maintenance at the depot level.  In the US, Marine Corps, personnel at the user level are not authorized to perform any corrective maintenance on the KWR-46. Instead, they can only remove and replace defective KWR-46 equipment. This policy will probably be identical in Canada.

Any preventive maintenance performed at the organizational level will be limited to cleaning, inspecting, and operational testing of the KWR-46 installation. The system operator or maintainer will remove any KWR-46 found to be defective and will replace it with the onboard spare. In the US, the Marine Corps maintains cyptographic repair facilities at the Naval Shipyard, Norfolk, Virginia, and Naval Electronics Center, San Diego, California.

Through the application of large scale integration technology (LSI), the KWR-46 provides enhanced reliability, reductions in space and power requirements, and improved electronic key distribution over existing security equipment.  ccording to the USS Pompanito web site, the KW46 system is no longer being used for fleet broadcast and has now been retired .

WIDTH (in)
DEPT (in)
DATA RATE (kbps)
KWR-46  7.60  4.90  16.80 22.90  50 bps - 9.6 kbps
KWT-46 7.75  4.78  16.80  22.90  50 bps - 9.6 kbps

Unit Cost:  $US 11,900 (in 1988) - no longer produced


1) Excerpts from US Marine Corps Order MCO 2040.7 dated Oct 26, 1988 which can be found on the Internet.
2) US Navy COMSEC web page.

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