The National Security Agency (NSA) is the cryptologic intelligence
and security agency of the US government. It is based in Fort Meade, Maryland
(USA) and has a nice museum, called the
National Crytologic Museum (NCM), that is open to the public.
As part of the American Department of Defence (DoD), the NSA is responsible
for the collection and analysis of foreign communications and foreign signals
It is also responsible for the protection of US government communications and
information systems from evesdropping by similar agencies elsewhere
As such, the NSA has (co)developed a range of cryptographic algorithms and
Most of these were initially intended for military and
government use, but some of them have been made available to a restricted group
of (commercial) customers as commercial off-the-shelf (COTS) products.
Below is an overview of the various types of encryption developed and
endorsed by the NSA. As most of the NSA's work is classified, the list
is neither complete nor correct.
The information below is based on public knowledge about NSA products,
algorithms and protocols.
Further down this page is also an overview of the
evolution of NSA encryption products.
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, regarding WWII, the Cold War and some other events.
These documents are available for download from the NSA website .
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.
More detailed information on
- Classified or sensitive US Government information (Top Secret)
This includes algorithms such as AES(256), BATON, FIREFLY,
used in a variety of products such as the
STU-III secure phone
and many military communication products, like the
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).
- National Security Information
This 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
- Unclassified sensitive US Government or commercial information
Also known as Sensitive, But Unclassified (SBU); used on non-national
Approved (unclassified) algorithms include DES, Tripple DES, AES, DSA and SHA.
A good example of a Type 3 product is the
CVAS III secure phone.
- Unevaluated commercial cryptographic equipment; not for government usage
The algorithms have been registered with
but are not
Federal Information Processing Standard (FIPS).
They may not be used for classified information.
- 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 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
One of the first NSA products to be developed after WWII was the
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 some of their allies (NATO).
The daily keys were distributed on paper key lists.
- 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.
- 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.
- 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.
- 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.
Although most of the NSA's work on encryption is classified, 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.
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,
SecNet-11, Sierra, SafeXcel-3340 and PSIAM.
NSA-developed cooperative key generation scheme, used for exchanging
EKMS public keys. Used in products like AIM, SafeXcel-3340, PSIAM,
- HAIPE IS
Interoperability Specification (IS) for the High Assurance Internet
Protocol Encryptor (HAIPE). Based on Internert 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.
Narrow band voice encryption used for radio and telephone communication.
Used with products like AIM, Cypris (SAVILLE I and II), Windster (SAVILLE I),
VINSON (KY-57) and
Joint development of GCHQ (UK) and the NSA (US).
Used for TTY broadcasts to submarines by AIM (2004).
High-speed link encryption. Used in products like
Generally used for Trunk Encryption Devices (TED).
Cryptographic algorithm used in products like Cypris (2 modes),
Windster and Indictor.
Cryptographic algorithm used in SafeXcel-3340.
Cryptographic algorithm used in NSA-developed crypto chips, such as
Cypris, Windster and Indictor.
Asymmetric-key algorithm used in products like
and the Palladium Secure Modem.
KEA was declassified by the NSA on 24 June 1998.
Block cipher algorithms used in products like
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.
- 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.
- AES - Advanced Encryption Standard
Block cipher. Specified in FIPS 197.
- 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 (incomplete) list shows which products are believed to
have been (partly) developed by the NSA:
In the early 1990s, the NSA developed the so-called Clipper Chip.
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.
The controversial Clipper Chip was announced in 1993 and was already defunct by 1996.
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