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USA Cipher Machines
Over the years, the USA produced many different cipher machines. In some cases, these machines were developed by the NSA (National Security Agency), but sometimes they were bought 'of the shelf' from existing manufacturers. As it is sometimes unclear who the developer or the manufacturer of a machine is, we've listed some of them on this page.
Breaking news about KL-7 
Using the latest information sent-in by our readers, Dirk Rijmenants has been able to release a fully functional and accurate simulator for the American KL-7 cipher machine. It runs on Windows and has a beautiful user interface. Furthermore, a fully operational KL-7 simulator has now been released by researchers from MIT as well. As this one was written in JAVA, it runs on virtually any platform. Available for download.
Devices described in this section:
Jefferson disk (or: Jefferson Wheel Cipher) Jefferson The Confederate Cipher Disk (a variant of the Vigenèr Cipher) used during the American Civil War CC Disk Giddings Field Message-Book with US Army Cipher Disk, used during the Spanish-American War in 1898. Giddings The Hagelin-designed M-209 (C-38) M-209 The Hagelin BC-38 (compatible with M-209) BC-38 ECM Mark II (SIGABA, CSP-888/889, CSP-2900, CSP-1600, CSP-1700) SIGABA TSEC/KL7 (Adonis, Pollux) KL-7 KL-51 (RACE) KL-51
KG-81 digital high-speed trunk encryption device KG-81 KG-84 digital line encryptor for telex signals KG-84 KY-68 Digital Secure Telephone KY-68 KY-57 (VINSON) Wide-band Voice and Data Encryption Unit KY-57 Narrow-band Voice and Data Terminal KY-99 AN/KYK-13 Key Transfer Device KYK-13 AN/CYZ-10 Data Transfer Device CYZ-10 Key Transfer Device MX-18290
Secure Telehone Unit STU-I (KY-70) STU-I Secure Telephone Unit STU-II Secure Telephone Unit STU-III Secure Terminal Equipment STE Type 3 Secure Telephone CVAS III AT&T TSD-3600-E (using the Clipper Chip) TSD-3600 AT&T/Lucent 1100 STU-III secure phone (later sold by General Dynamics) 1100 AT&T/Lucent 4100 crypto phone (later sold by General Dynamics) 4100
Clipper Chip (used for key escrow) Clipper KIV-7, embeddable KG-84 COMSEC module KIV-7 Fortezza Crypto Card Fortezza Key Storage Device KSD-64 (and others) KSD-64 US National Security Agency NSA The U-229/U connector and its variants U-229 KD-100 key tape disintegrator KD-100 Washington-Moscow Hotline Hotline

Based on the C-38, Boris Hagelin developed the M-209 for the American Army, shortly before the outbreak of WWII. The small compact mechanical machine remained in service until the late 1960s.

As the machine could be broken by the Germans in less than 4 hours, it was only used for tactical messages. The M-209 was built under licence by several companies, such as Smith Corona.

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M-209-A opened and ready for use
The BC-38 was a motor-driven, keyboard-operated, mechanical cipher machine built by Hagelin in Sweden. Like the M-209 it was based on the C-38.

As it was compatible with the M-209, it was often used in large communication centres. The BC-38 was also used by other countries during and after WWII, just like the later BC-543.

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Typical view of the BC-38 with the lever down
The ECM Mark II was a cipher machine based on the electromechanical rotor principle. It was developed by the USA shortly before WWII and was used during the war by the Allied forces.

It has been in service until the 1950s and was even used by NATO shortly after WWII.

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Right angle view of the SIGABA, showing the paper path.
The TSEC/KL-7 was an off-line cipher machine built in the 1950s by the US National Security Agency (NSA) and served during an important part of the Cold War. It was used by the USA and manu of its NATO partners. Like the German Enigma machine, it uses rotors and alphabet substitution as its main principle.

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KL-51 (RACE)
The KL-51 replaced the aging KL-7 in the US Army in the early 1980s. It was a fully electronic machine that was also used by NATO and by the Canadian Forces, where it was known as RACE.

KL-51 is a compact unit that was used for offline encryption and decryption of teleprinter messages. It can be connected to an external teleprinter and an external paper tape puncher.

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KL-51 (RACE) with open lid and expanded paper holder
Key fill devices
A key transfer device is an electronic device that is used (most commonly by the military) for the distribution of cryptographic material, such as crypto keys and frequency hopping tables.

Key fillers often use a standard data protocols, but proprietary protocols are used as well. Many key fill units have the same 6-pin U-229 connector allowing connection to standard radio sets, such as HAVE QUICK and SINCGARS.

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KYK-13 key loader

The KY-68 was a digital secure voice terminal (crypto phone) used by the US Army and Navy. It was introduced in the early 1990s and was used until 2010. They are currently being replaced by the STE.

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KY-68 Digital Secure Voice Terminal

The KY-57 was a wide-band voice encryption device developed by the USA during the late 1970s to replace the ageing NESTOR voice crypto systems. For many years it was the US Army's main crypto 'workhorse'.

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KY-57 voice encryption unit

The TSEC/KY-99A was an advanced narrow-band digital voice and data terminal, developed by the USA during the 1980s to replace the KY-57 with which it is backwards compatible.

It features both CVSD modulation and enhanced LPC-10 voice coding. The KY-99 can be used over narrow-band radio channels.

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STU-I was the first generation secure digital telephone, developed by the NSA in the late 1960s and the early 1970s. It was a bulky unit consisting of a large cabinet containing the actual electronic circuits and a desktop terminal that was similar to a normal telephone set.

The STU-I is also known as the KY-70. It replaced the KY-3 and was succeeded in the 1980s by the STU-II (KY-71).

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DNS handset for IVSN

The STU-II was the second generation secure telephone developed by the NSA in the 1980s. It replaced the older STU-I and the KY-3. The STU-II is also known as KY-71 or TSEC/KY-71.

The STU-II consisted of a large rackmount unit and a telephone-style control unit (shown here).

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The HYX-71A desktop unit of the STU-II (KY-71)

The STU-III is the third and last of a series of secure telephone units (STU), developed in the US by the National Security Agency (NSA), for the highest level of security (Type 1 and 2).

The STU-III was introduced in 1987 as the successor to the bulky STU-II. It was built by several manuafacturers, such as Motorola, RCA (later: L3) and AT&T.

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Motorola SECTEL 2500 with CIK

Secure Terminal Equipment (STE) was developed by the NSA in the early 1990s as the successor to the extremely successful STU-III. It was built under contract by L3 Communications and can be connected to a variety of networks, including PSTN, ISDN and (optionally) VoIP.

STE units were still in use in 2012.

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Secure Terminal Equipment (STE) - Tactical

The CVAS III was an NSA Type 3 cryptographic product, developed and buit by A-O Electronics in the USA. It was used for unclassified but sensitive information. It used cryptographic algorithms such as DES and EDAS.

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CVAS III-E Secure Telephone

The KG-84 is an electronic encryption device developed by the National Security Agency (NSA) in the USA. It was used for secure transmission of digital data over a variety of networks, such as landlines, satellites, microwave links and Telex.

Many modern encryption devices are still backwards compatible with the KG-84, for example the SafeNet KIV-7 (see below).

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Front panel of the KG-84

KIV-7 is a compact miniaturized embeddable version of the military KG-84 encryption device. It was developed by AlliedSignal Corporation and manufactured in the mid-1990s by Mykotronx (now: SafeNet) in the USA, as a commercial-off-the-shelf (COTS) product, to meet the growing demand for secure data communication links.

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The KIV-7 with CIK

The TSD-3600-E was an advanced telephone security device, developed by AT&T (USA) in 1992. It was based on the controversial Clipper Chip, forcing users to escrow their cryptographic keys. The TSD-3600 was a small white box that was connected between the handset and the phone.

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AT&T TSD-3600 phone encryptor

AT&T (later: Lucent) was appointed in 1987 as one of the manufacturers of the STU-III secure telephones. The 1100 shown here was one of the last STU-III phones developed by AT&T.

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AT&T STU-III with CIK installed

Motorola SECTEL
Motorola was one of three manufacturers appointed by the US Government to develop and make STU-III secure telephones, based on the 1987 design by the NSA.

Motorola subsequently released the SECTEL range of secure phones, of which the SECTEL 1500 delivers the highest level of security.

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Typical view of the Motorola SECTEL 9600 (STU-III)

Confederate Cipher Disk
During the American Civil War (1861-1865), the Confederate States of America used a variant of the Vigenère Cipher (sometimes called the Alberti Disc) to protect the contents of their messages.

Although the cipher has often been claimed to be unbreakable, it can be broken by various hand and mathematical methods.

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A replica of the Confederate Cipher Disc on top of its leather bag.

Spanish-American War
The same cipher disc was used during the Spanish-American War of 1898, when a paper-based version of it was included in the Giddings Field Message-Book, a smal A6-size booklet with a green leather cover and a short pencil.

Message, written down on a message pad, were encrypted with the cipher disc and then filed in a pocket of the book.

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US Army Cipher Disk

Jefferson Disk
The Jefferson Disk is a manual cipher system that consists of a set of wheels on an axle. Each wheel has the 26 letters of the Latin alphabet on its circumfere in a pre-determinded scrambled arrangement. Each wheel has a unique number and the order is determinded by a code book.

The M-94 was derrived from this system.

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The KSD-64 is a so-called Key Storage Device developed by the NSA for use with electronic cryptographic equipment, such as the STU-III secure telephones. It can be used for a variety of applications, ranging from Key Fillers to Crypto Ignition Keys (CIKs).

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KSD-64 Key Storage Device

Clipper Chip
The Clipper Chip was a chipset developed and promoted by the US Government. It was intended for the implementation in secure voice equipment, such as crypto phones, and required users to give their cryptographic keys in escrow to the government.

This would allow law enforcement agencies to decrypt any traffic for surveillance and intelligence purposes.

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Close-up of the Clipper Chip inside the TSD-3600

U-229 connector
Most American and NATO equipment uses a standardized connector for audio, digital data and (crypto) FILL purposes. This connector is commonly called U-229 and is used for analog and digital data.

It supports various data protocols, such as DS-102 and DS-101. We have collected all currently known pinouts of this connector on a single page.

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Further information

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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Thursday, 27 March 2014 - 12:11 CET
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