Homepage
Crypto
Index
Glossary
Enigma
Hagelin
Fialka
Nema
AT&T
Datotek
Gretag
HELL
ITT
Motorola
Mils
OMI
Philips
Racal
Siemens
STK
Tadiran
Telsy
Teltron
Transvertex
TST
USA
USSR
UK
Yugoslavia
Voice
Hand
OTP
EMU
Mixers
Phones
FILL
Codebooks
Algorithms
Spy radio
Burst encoders
Intercept
Covert
Radio
PC
Telex
People
Agencies
Manufacturers
• • • Donate • • •
Kits
Shop
News
Events
Wanted
Contact
About
Links
   Logo (click for homepage)
KG-81   WALBURN
High-speed Trunk Encryption Device - wanted item

KG-81 was a high-speed Trunk Encryption Device (TED), also known as a Bulk Encryption Device, developed by the American National Security Agency (NSA), probably in the late 1970s. It uses the WALBURN cryptographic algorithm, and is primarily intended for the encryption of microwave trunks, high-speed landline circuits, video teleconferencing, T-1 satellite channels, etc. [1].
 
Like the other members of the WALBURN family, the KG-81 was certified to encrypt and decrypt messages up to the level of TOP SECRET. The device itself is an UNCLASSIFIED controlled cryptographic item (CCI) as long as it is unkeyed. When keyed, it assumes the classification level of the key in use. All members of the WALBURN family are suitable for simplex and full-duplex traffic, and are interoperable.

The image on the right shows the front panel of a KG-81 [2]. The front panel measures 145 x 155 mm and the unit is 470 mm deep. Typically, two KG-81 units were mounted side-by-side in a special 19" rackmount adapter unit.
  
Font view of the KG-81. Photograph by Ralph Simpson.

Cryptographic keys, or crypto variables as they are called in NSA language, are loaded into the device by means of a standard key transfer device, or key-filler, such as the KYK-13. The key-filler is connected to the 5-pin U-229 connector at the font panel, marked FILL. Once connected, the MODE-switch at the top left is set to LOAD and the ACTIVATE button is pressed.

The KG-81 was capable of encrypting and decrypting data at a maximum speed of 20 Mbps, which was extremely fast at the time. In the late 1980s, the KG-81 was replaced by the much faster KG-95 that ran at 50 Mbps [1]. None of the WALBURN family members are in production anymore and they have all been replaced by the backwards compatible and interoperable KIV-19.
 
Co-production by Philips
In Europe, KG-81 units were built by Philips Usfa, under licence of the NSA, from 1982 onwards. Over the years, Philips produced hundreds of KG-81 units, suitable 19" racks and interfaces for NATO. This was the result of a NATO evaluation, codenamed HISPEED, a few years earlier, in which Philips dropped its SATCOLEX product in return for co-production of the KG-81.
 
The image on the right shows an original black & white photograph that was made at Philips Usfa in the early 1980s [3]. It shows part of a 19" rack, with two KG-81 units mounted in a single frame. Below the encryption units is a Philips-designed line interface for connection to the teleprinter network (telex).

 More about Philips HISPEED
  
Close-up of a 19'' rack with KG-81 units

 
References
  1. Federation of American Scientists (FAS), WALBURN Family and KIV-19
    FAS website. 5 May 1998. Retrieved December 2012.

  2. Ralph Simpson, Photograph of KG-81 front panel
    Retrieved December 2012.

  3. Crypto Museum, Photographs of KG-81 units in the HISPEED project
    Crypto Museum Photo Archive #301324.

Further information

Any links shown in red are currently unavailable. If you like the information on this website, why not make a donation?
Crypto Museum. Last changed: Sunday, 31 May 2015 - 07:06 CET.
Click for homepage