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National Security Agency

The US National Security Agency (NSA) is the cryptologic intelligence and security agency of the United States Government, based in Fort Meade (Maryland, USA). The NSA is part of the American Department of Defence (DoD), and is responsible for the collection (interception) and analysis of foreign communications and foreign signals intelligence (signals intelligence and cryptanalysis).

The NSA is also responsible for the protection of US government communications and information systems from evesdropping by similar agencies from other nations. As such, the NSA has (co) developed a range of cryptographic algorithms and encryption devices. Most of these products were initially developed for use by the US military and the US government, but some have been made available to restricted commercial users as well, often as commercial off-the-shelf (COTS) products, via various suppliers.

As part of the NSA's Center for Cryptologic History, the agency has its own museum, called the National Cryptologic Museum (NCM), just outside the main gates. The NCM is open to the public, and serves as the agency's principal public gateway.
source: wikipedia

Below is a non-exhaustive overview of the various types of encryption products developed and/or endorsed by the NSA. As most of the NSA's work is classified, there may be omissions or errors. The information below is based on publicly available information about NSA products, algorithms and protocols. We also show the evolution of the NSA encryption products, along with examples of devices that contain NSA algorithms. Finally, we show cases in which the NSA has intervened in order to weaken an existing algorithm. If you find any omissions or mistakes, please contact us.

NSA headquarters in For Meade (Maryland, USA)

The NSA headquarters in Fort Meade (Maryland, USA) [2]

NSA devices on this website
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 Terminal Equipment
TSEC/KL7 (Adonis, Pollux) TSEC/KW-7 (Orestes) KG-13 key generator
KW-26 (Romulus) cipher machine KG-81 digital high-speed trunk encryption device KG-84 data encryptor Fortezza Crypto Card Enhanced Crypto Card Functional electronic circuits NSA-developed covert listening devices (bugs)
NSA operations on this website
Gentleman's Agreement
Operation RUBICON (THESAURUS) - the secret purchase of Crypto AG
Cryptologic history
The cryptologic history of the NSA is layed out in several (internal) publications that have been written over the years by NSA historians. In recent years, the NSA has (partly) declassified some of these publications, in particular the ones regarding WWII, the Cold War and some other events. These documents are available for download from the NSA website [1].

NSA Product Types
Depending on the required (and allowed) level of security, the NSA has defined various Types of encryption. The lower the number, the higher the security level. E.g. Type 1 products are for use by the US government for top secret material [3]. The following Product Types are known:

  1. Classified or sensitive US Government information - TOP SECRET
    This includes algorithms such as AES(256), BATON, FIREFLY, HAVEQUICK, and SAVILLE, that are used in products like the STU-III secure phone and many military communication products, like the KG-84, KIV-7, KY-57 and KY-99. Type 1 products are only used by the US Government, their contractors, and federally sponsored non-US Government activities, in accordance with the International Traffic in Arms Regulations (ITAR). Type 1 algorithms are also used by NATO and by the administrations of some NATO countries.  More 

  2. National Security Information
    Includes products like CORDOBA, KEA and SKIPJACK used in equipment like the Cypris cypto chip and the Fortezza (Plus) crypto cards. It may be used for unclassified national security information. The equipment is unclassified, but the algorithms and keys are. Type 2 products are subject to International Traffic in Arms Regulations (ITAR).  More 

  3. Unclassified sensitive US Government or commercial information
    Also known as Sensitive, But Unclassified (SBU); used on non-national security systems. Approved (unclassified) algorithms include DES, Tripple DES 1 , AES, DSA and SHA.
    A good example of a Type 3 product is the CVAS III secure phone.  More 

  4. Unevaluated commercial cryptographic equipment; not for government usage
    The algorithms have been registered with NIST but are not Federal Information Processing Standard (FIPS). They may not be used for classified information.
  1. DES has meanwhile been withdrawn as an official FIPS standard.

Algorithm Suites
  • Suite A
    Unpublished NSA algorithms intended for highly sensitive communication and critical authentication systems. Generally used in combination with Type 1 and 2 equipment.

  • Suite B
    NSA endorsed cryptographic algorithms for use as an interoperable base for both unclassified and most-classified information. Introduced on 16 February 2005.
    (More on the NSA website...)
Another way of categorizing the encryption systems developed by or on behalf of the NSA, is by looking at the evolution of their development. This can be divided into several generations that are listed below. More detailed information is available on Wikipedia [4].

  1. Electro-mechanical
    One of the first NSA products to be developed after WWII was the KL-7. It was introduced in the 1950s and was partly based on the war-time SIGABA. The KL-7 was used by the US Military and its NATO allies. The daily keys were distributed on paper key lists.

  2. Vacuum tubes
    In the 1960s and 1970s, electronic cipher machines with vacuum tubes (valves) were developed. Punched cards were used for key distribution. Some of these systems remained in use until the mid-1980s. An example of a cipher machine based on vacuum tubes is the KW-26 that was used by the US Navy.

  3. Integrated Circuits (ICs)
    The next generation was developed during the 1980s and was based on transistor logic, using integrated circuits (ICs). This made devices significantly smaller and allowed for faster and stronger cryptographic algorithms. Keys were loaded through a standardized connector at the front panel of each device. Initially they were distributed on punched paper tape that was pulled though a reader (e.g. the KOI-18) but these were eventually replaced by electronic devices such as the KYK-13.

  4. Electronic Key Distribution
    During the 1990s, more modern (commercial) electronics were introduced. This allowed even smaller systems to be developed and introduced electronic methods for key distribution. At this stage, the electronic security token or Crypto Ignition Key (CIK) was introduced, protecting the electronically stored keys and allowing for easier key distribution. An example of a CIK is the KSD-64 that was developed by the NSA for products like the Motorola SECTEL 2500 secure telephone (STU-III). Traffic Encryption Keys (TEKs) were distributed with a new generation of electronic Data Transfer Devices (DTD) such as the AN/CYZ-10.

  5. Network-centric systems
    From 2000 onwards, communication is increasingly based on digital computer networks, such as the internet. The NSA has developed an interoperable standard called HAIPE to allow government, agencies and others to securely exchange data over unsecure networks and satellite links. An example of such a product is the KIV-7 family of embeddable KG-84 encryption devices.
Transfer protocols
Over the years, the NSA has developed and endorsed a common standard for transferring keys (and other material) from a key distribution center (KDC) to a supporting radio or encryption device, by means of an external FILL device. Two versions of this standard are known:

  • DS-101 — EKMS 603
    This is the most recent transfer protocol that is used with the current generation of FILL devices, radio sets and encryption equipment. It superceedes DS-102 and can be used for transferring crypto keys, frequency hopping data, software updates, etc.  More

  • DS-102 — EKMS 608
    This is a synchronous serial protocol that was used with the first generation of Key Fill Devices, such as the KYK-13. It is the predecessor of the DS-101 protocol, and can be used for the distribution of key material and frequency hopping tables.  More
Although most of the NSA's work on encryption is secret, some information has been published in the past, either as part of the NSA's participation in standards processes, or after an algorithm has been declassified. Below is an (incomplete) overview of NSA-developed approved algorithms.

Type 1
    Cryptographic algorithm used in products like AIM, SafeXcel-3340 and PSIAM.

  • AES (256)
    256-bit block cipher algorithm, used in numerous products. Specified in FIPS 197.

    Block cipher algorithm, used with products like PKCS#11, CDSA/CSSM, AIM, Cypris, APCO Project 25, MYK-85, Fortezza Plus, SecNet-11, Sierra, SafeXcel-3340, PSIAM and the Philips GCD-Φ.

    NSA-developed cooperative key generation scheme, used for exchanging EKMS public keys. Used in products like AIM, SafeXcel-3340, PSIAM, STU-III, STE and SCIP.

    Interoperability Specification (IS) for the High Assurance Internet Protocol Encryptor (HAIPE). Based on Internet Protocol Security (IPsec), with additional restrictions and enhancements. Used in products like KOV-26 (Talon), KIV-7M, KG-175 (TACLANE), KG-240A, KG-245, KG-250 and KG-255.

    Frequency Hopping System used for ECCM. Implemented in the Cypris crypto chip.

    Joint development of GCHQ (UK) and the NSA. Used for narrow-band voice encryption in radio and telephone communication. Used in products like AIM, Cypris (SAVILLE I and II), Windster (SAVILLE I), INDICTOR (SAVILLE I), VINSON (KY-57), Spendex 40, Spendex 50 and Cougar radios. Also used for data encryption in products like KG-84 and KIV-7  More...

    Used for TTY broadcasts to submarines by AIM (2004).

    High-speed link encryption. Used in products like KG-81, KG-94, KG-194, KG-95 and AIM (2004). Generally used for Trunk Encryption Devices (TED).  More...

    Cryptographic algorithm used in products like Cypris (2 modes), Windster and INDICTOR.

    Cryptographic algorithm used in SafeXcel-3340.
Type 2
    Cryptographic algorithm used in NSA-developed crypto chips, such as Cypris, Windster and Indictor.

  • KEA
    Asymmetric-key algorithm used in products like Fortezza, Fortezza Plus and the Palladium Secure Modem. KEA was declassified by the NSA on 24 June 1998.  More...

    Block cipher algorithm used in products like Fortezza, Fortezza Plus and the Palladium Secure Modem. It was also used in the so-called Clipper Chip that was featured in products like the AT&T TSD-3600 telephone encryptor. The Skipjack algorithm was declassified by the NSA on 24 June 1998.
Type 3
  • DES - Data Encryption Standard
    Block cipher. Used in many NSA Type 3 products, such as the Motorola SECTEL 2500 (in Type 3 mode). Specified in FIPS 46-3 and withdrawn in 2004.

  • AES - Advanced Encryption Standard
    Block cipher. Specified in FIPS 197 and released in 2001.

  • DSA - Digital Signature Algorithm
    Used for digital signatures. Specified in FIPS 186.

  • SHA - Secure Hash Algorithm
    Cryptographic hash function. Specified in FIPS 180-2.
The following (non-exhaustive) list shows which products are believed to have been (partly) developed by or for the NSA. Some of these products are covered on this website.

Although the NSA does not publish information about its methods and/or its targets, it is known that in the past the agency has regularly tried to covertly get access to classified information by weakening or replacing encryption algorithms, or by persuading other parties to do so on their behalf. Below are some examples of documented cases in which the NSA has been involved.

Key Escrow
In the early 1990s, the NSA made an attempt to control the availability of strong encryption to the general public. They developed a special chip that was intended for the implementation in secure voice equipment and required users to give the cryptographic keys in escrow to the government.

This would allow law enforcement agencies to decrypt any traffic for warranted surveillance and intelligence purposes. The device became known as the Clipper Chip and was announced in 1993.

The device used the Skipjack algorithm, but was was not embraced by the public. Furthermore it appreared to be seriously flawed, as a result of which it was already defunct by 1996.

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

During WWII, Boris Hagelin made fame by supplying the M-209 cipher machine to the US Army. In the years following the war, it was frequently speculated that Hagelin's company – Crypto AG – had created backdoors in its equipment, to the benefit of the NSA.

 More information
The Hagelin HC-530 removed from it carrying case

Philips PX-1000
PX-1000 was a small pocket terminal, developed around 1980 by Text-Lite in the Netherlands and marketed worldwide by Philips. Messages were encrypted with DES and could be sent over a regular telephone line via the built-in modem.

In 1983, the NSA expressed its concern about the availability of DES to the general public — in an affordable device — and persuaded Philips to implement an alternative stream cipher that they (the NSA) had developed.

 More information

Original PX-1000 made in 1983

Around 1983, the Finnish company Nokia produced two message terminals for the Ministry of Defence and NATO: SANLA and PARSA. The terminals used DES encryption and were able to send the messages at high speed (burst).

To prevent the use of DES outside NATO, the NSA asked the Dutch company Philips Usfa to implement an alternative algorithm, that would be supplied to non-NATO countries.

 More information

Crypto AG
From the mid-1960s on, when the Swiss firm Crypto AG (Hagelin) made the move from mechanical to electronic cipher machines, the NSA designed some of their cryptologics.

Eventually, when Crypto AG was bought in 1970 by the CIA and its German counterpart the BND, the NSA had full control over the readability of the equipment. This project – internally known as Operation RUBICON – lasted until 2018.

 More information

Tailored Access Operations · TAO
The Office of Tailored Access Operations (TAO) is a cyber-warfare intelligence gathering unit of the NSA. The unit is active since approx. 1998 and identified, monitors, infiltrates and gathers information from target computer systems, using a wide variety of hardware and software tools.

The hardware and software tools that are used to eavesdrop on target computers, on offices and on private homes — sometimes referred to as the NSA toolbox — are developed by the NSA's Advanced Network Technology division (ANT), sometimes in cooperation with the British GCHQ, and are listed in the ANT product catalog.

A good example of an ANT bugging tool, is the LOUDAUTO audio bug shown in the image on the right, that was developed around 2007. Although it was supposed to be secret until 2032, it was publicly disclosed in 2013 by Edward Snowden.
LOUDAUTO bugs from the ANT product catalog - click for further information

The ANT Product Catalog reveals the technical details of approx. 50 devices and software products that illustrate the state-of-the-art at the NSA around 2008 - 2009. Most (if not all) products are made from Commercial Off-The-Shelf (COTS) components, as a result of which the clandestine devices can not be attributed to the NSA when they are accidentally discovered.

 ANT Product Catalog

  1. European Axis Signal Intelligence in WWII - in nine volumes
    NSA (see below), 1 May 1946. TOP SECRET CREAM. 1

  2. David G. Boak, A History of U.S. Communications Security
    Lectures, 1966. Revised July 1973. 2

  3. David G. Boak, A History of U.S. Communications, Volume II Security
    Lectures, July 1981. 3

  4. NSA, Field Generation and Over-the-Air Distribution of COMSEC key... support of Tactical Operations and Excercises. Handling Instructions.
    NAG-16F. May 2001. Unclassified (U) — For Official Use Only (FOUO).
European Axis Signal Intelligence in WWII 1
  1. Synopsis
  2. Notes on German High Level Cryptography and Cryptanalysis
  3. The Signal Intelligence Agency of the Supreme Command, Armed Forces
  4. The Signal Intelligence Service of the Army High Command
  5. The German Air Force Signal Intelligence Service
  6. The Foreign Office Cryptanalytic Section
  7. Goering's 'Research' Bureau
  8. Miscellaneous
  9. German Traffic Analysis of Russian Communications
  1. Declassified and approved for release by NSA on 1 June 2009. EO 12958, Declass 58017.
  2. Declassified by Interagency Security Classification Appeals Panel, 14 October 2015.
    EO 13526, section 5.3(b)(3).
  3. Declassified by NSA 11 December 2008. EO 12958.

  1. National Security Agency (NSA), Cryptologic Histories
    NSA website. Downloadable documents. Retrieved February 2013.

  2. Wikimedia Commons, Photograph of NSA headquarters in Fort Meade, Maryland, USA
    Obtained from NSA website. Retrieved August 2013.

  3. Wikipedia, NSA cryptography
    Retrieved February 2013.

  4. Wikipedia, NSA encryption systems
    Retrieved February 2013.
Further information
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Crypto Museum. Created: Sunday 12 August 2012. Last changed: Thursday, 23 April 2020 - 19:51 CET.
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