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United States of America

Over the years, the USA produced many different cipher machines. In some cases, these machines were developed by the NSA (National Security Agency), but often they were developed and built elsewhere, sometimes even as a Commercial off-the-shelf (COTS) product. As it is often unclear who the developer or the manufacturer of a machine is, we've listed some of them on this page.   
Great Seal of the United States of America. Image via Wikipedia [1].

US cipher machines on this website
Jefferson disk (or: Jefferson Wheel Cipher)
The Confederate Cipher Disk (a variant of the Vigenèr Cipher) used during the American Civil War
M-94 manual cipher device
Giddings Field Message-Book with US Army Cipher Disk, used during the Spanish-American War in 1898.
The Hagelin-designed M-209 (C-38)
The Hagelin BC-38 (compatible with M-209)
ECM Mark II (SIGABA, CSP-888/889, CSP-2900, CSP-1600, CSP-1700)
SIGTOT one-time tape cipher machine (US)
SIGSALY secure telephony system (Ciphony I)
KL-7 rotor-based cipher machine (USA)
TSEC/KW-7 (Orestes)
KL-51 (RACE)
KG-40 and KG-40A Link 11 encryption device
KG-81 digital high-speed trunk encryption device
KG-84 data encryptor
KY-57 (VINSON) Wide-band Voice and Data Encryption Unit
KY-99 (MINTERM) Narrow-band Voice and Data Terminal
Voice scrambler handset
AN/KOI-18 Key Tape Reader
AN/KYK-13 Key Transfer Device
AN/CYZ-10 Data Transfer Device
Key Transfer Device
KY-9 narrow-band secure voice system
KY-3 wideband secure voice system with KYX-9 desk set
HY-2 narrow-band secure voice system (with KG-13 key generator)
Secure Telehone Unit STU-I (KY-70)
Secure Telephone Unit
Secure Telephone Unit
Secure Telephone Unit
Motorola STU-III/R
Secure Terminal Equipment
vIPer Universal Secure Phone
Type 3 Secure Telephone
AT&T TSD-3600-E (using the Clipper Chip)
AT&T/Lucent 1100 STU-III secure phone (later sold by General Dynamics)
AT&T/Lucent 4100 crypto phone (later sold by General Dynamics)
Digital Subscriber Voice Terminal
Digital Message Device (DMD) used as part of OA-8990/P Digital Message Device Group
Clipper Chip (used for key escrow)
KIV-7, embeddable KG-84 COMSEC module
Datotek Inc (Texas, USA)
Harris Corporation
Miniature encryptor for burst messages
Fortezza Crypto Card
Enhanced Crypto Card
Key Storage Device KSD-64 (and others)
The U-229/U connector and its variants
KD-100 key tape disintegrator
US National Security Agency
Washington-Moscow 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 for some time 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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One of the first fully electronic US cipher machines was the KW-7. It was introduced around 1960 and was used by the US Navy, NATO, Australia and New Zealand, and by the Foreign Office of several friendly nations.

The KW-7 was used until the mid-1980s, and was replaced by the KG-84 and eventually by the much smaller KIV-7.

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KW-7 with open door
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

KY-68   DSVT
The KY-68 was a digital secure voice terminal (crypto phone), developed by the NSA and used by the US Army and Navy. It was introduced in the early 1990s and was used until 2010. They have since been replaced by the STE.

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KY-68 digital subscriber voice terminal (DSVT)

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 terminal (ANDVT), 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 and is also suitable for data transmission.

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Although certainly not the most secure solution, the KY-189 voice scrambler offered reasonable security for tactical applications in the early 90s.

The unit is housed in a standard military handset and can be connected to existing VHF and UHF radios. It was powered by an internal 9V battery, or by the radio to which is was connected.

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KY-189 scrambler handset

SIGSALY   Ciphony I
SIGSALY was the world's first secure unbreakable wireless telephone encryption system, developed during WWII by Bell Labs in the US, and built by Western Electric in New York.

SIGSALY was introduced in 1943 and was first used for secure conversations between London and Washington. In total, 12 SIGSALY terminals were built, each of which consisted of more than 30 full-hight 19" racks and four turntables.

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KY-9 was a narrow-band voice encryption system that was developed in the late 1950s. It had a data rate of 1650 baud and could be used on ordinary analogue telephone lines, but had a rather bad audio voice quality.

It was approved for all levels of classification and was installed with the Chiefs of Staffs, the Joint War Room, NORAD, the US President, the British Prime Minister and several US Embassies.

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KY-3 was a wide-band voice encryption system, developed by Bendix Corporation for the NSA. It was introduced in 1962/63 and had an excellent voice quality, but could be used one high-fidelity subscriber lines only.

The image on the right shows the KYX-9 remote desk set that was commonly used to operate the KY-3. There was also an internal KYX-10 unit.

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HY-2 was the successor to the KY-9. It had a slightly better data rate (2400 baud), but had to be used in combination with the large external KG-13 key generator. Nevertheless, the audio quality not very good, resulting in a typical 'Mickey Mouse' style voice.

For this reason, U.S. President Lyndon B. Johnson refused to use the HY-2 and preferred the much better KY-3 whenever it was available.

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KG-13 was a fairly large key generator/mixer, developed by the NSA around 1963. It was fully transistorized and built with FLYBALL technology. KG-13 was intended for use with an external data-generating device, such as the HY-2 voice digitiser or vocoder, and approved by the NSA for all levels of classification.

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STU-I   KY-70
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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STU-I voice terminal

STU-II   KY-71
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 and was the successor to the bulky STU-II. It was built by several manuafacturers, such as Motorola, RCA (later: L3) and AT&T. A NATO-version was available as the STU-II/B (KY-71D).

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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

CK-42 was a miniature encryption device for high-speed burst transmissions by secret agents. It was used by the CIA in a variety of countries, in combination with spy radio sets like the CDS-501 and the RS-804.

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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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As a proof of concept for the so-called Vernam Cipher (1918), the Western Union Telegraph Company built the Telekrypton around 1933.

The machine was extremely large and had a number of weaknesses, but was later improved and used as the basis for the British/Canadian Rockex cipher machine.

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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

The KY-879/P was a Digital Message Device (DMD) made by Racal in the UK for the US Special Forces. It allows burst transmissions of coded messages and minimizes the risk of detection by means of Radio Direction Finding.

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Operating the MA-4450

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 audio 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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  1. Wikipedia, United States
    Retrieved September 2009.
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© Crypto Museum. Created: Tuesday 04 August 2009. Last changed: Friday, 13 January 2023 - 14:57 CET.
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