The

National Security Agency The National Security Agency (NSA) is a national-level intelligence agency of the United States Department of Defense, under the authority of the Director of National Intelligence (DNI). The NSA is responsible for global monitoring, collecti ...

took over responsibility for all U.S. Government

encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...

systems when it was formed in 1952. The technical details of most NSA-approved systems are still classified, but much more about its early systems have become known and its most modern systems share at least some features with commercial products.

Rotor machine In cryptography, a rotor machine is an electro-mechanical stream cipher device used for encrypting and decrypting messages. Rotor machines were the cryptographic state-of-the-art for much of the 20th century; they were in widespread use in the 19 ...

s from the 1940s and 1950s were mechanical marvels. The first generation electronic systems were quirky devices with cantankerous

punched card A punched card (also punch card or punched-card) is a piece of stiff paper that holds digital data represented by the presence or absence of holes in predefined positions. Punched cards were once common in data processing applications or to di ...

readers for loading keys and failure-prone, tricky-to-maintain

vacuum tube A vacuum tube, electron tube, valve (British usage), or tube (North America), is a device that controls electric current flow in a high vacuum between electrodes to which an electric voltage, potential difference has been applied. The type kn ...

circuitry. Late 20th century systems are just

black box In science, computing, and engineering, a black box is a system which can be viewed in terms of its inputs and outputs (or transfer characteristics), without any knowledge of its internal workings. Its implementation is "opaque" (black). The te ...

es, often literally. In fact they are called '' blackers'' in NSA parlance because they convert

plaintext In cryptography, plaintext usually means unencrypted information pending input into cryptographic algorithms, usually encryption algorithms. This usually refers to data that is transmitted or stored unencrypted. Overview With the advent of comp ...

classified signals (''red'') into encrypted unclassified

ciphertext In cryptography, ciphertext or cyphertext is the result of encryption performed on plaintext using an algorithm, called a cipher. Ciphertext is also known as encrypted or encoded information because it contains a form of the original plaintext ...

signals (''black''). They typically have

electrical connector Components of an electrical circuit are electrically connected if an electric current can run between them through an electrical conductor. An electrical connector is an electromechanical device used to create an electrical connection between ...

s for the red signals, the black signals, electrical power, and a port for loading keys. Controls can be limited to selecting between key fill, normal operation, and diagnostic modes and an all important '' zeroize'' button that erases

classified information Classified information is material that a government body deems to be sensitive information that must be protected. Access is restricted by law or regulation to particular groups of people with the necessary security clearance and need to know, ...

including keys and perhaps the encryption algorithms. 21st century systems often contain all the sensitive cryptographic functions on a single, tamper-resistant integrated circuit that supports multiple algorithms and allows over-the-air or network re keying, so that a single hand-held field radio, such as the

AN/PRC-148 The AN/PRC-148 Multiband Inter/Intra Team Radio (MBITR) is the most widely fielded handheld multiband, tactical software-defined radio, used by NATO forces around the world. The radio is built by Thales Communications, a subsidiary of the France-b ...

AN/PRC-152 The AN/PRC-152 Multiband Handheld Radio, also known as Harris Falcon III, is a portable, compact, tactical software-defined combat-net radio manufactured by Harris Corporation. It is compliant without waivers to the Joint Tactical Radio System ( ...

, can interoperate with most current NSA cryptosystems.

Security factors

NSA has to deal with many factors in ensuring the security of communication and information ( COMSEC and

INFOSEC Information security, sometimes shortened to InfoSec, is the practice of protecting information by mitigating information risks. It is part of information risk management. It typically involves preventing or reducing the probability of unauthorize ...

in NSA jargon): * ''

Confidentiality Confidentiality involves a set of rules or a promise usually executed through confidentiality agreements that limits the access or places restrictions on certain types of information. Legal confidentiality By law, lawyers are often required ...

'' and ''

authentication Authentication (from ''authentikos'', "real, genuine", from αὐθέντης ''authentes'', "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicati ...

'' – making sure messages cannot be read by unauthorized people and that they cannot be forged (

nonrepudiation Non-repudiation refers to a situation where a statement's author cannot successfully dispute its authorship or the validity of an associated contract. The term is often seen in a legal setting when the authenticity of a signature is being challenged ...

). Little is publicly known about the algorithms NSA has developed for protecting

, what NSA calls Type 1 algorithms. In 2003, for the first time in its history, NSA approved two published algorithms, Skipjack and AES for Type 1 use in NSA approved systems. * ''Traffic flow security'' – making sure an adversary cannot obtain information from

traffic analysis Traffic analysis is the process of intercepting and examining messages in order to deduce information from patterns in communication, it can be performed even when the messages are encrypted. In general, the greater the number of messages observed ...

, often accomplished by

link encryption Link encryption is an approach to communications security that encrypts and decrypts all network traffic at each network routing point (e.g. network switch, or node through which it passes) until arrival at its final destination. This repeated dec ...

. * ''

Key management Key management refers to management of cryptographic keys in a cryptosystem. This includes dealing with the generation, exchange, storage, use, crypto-shredding (destruction) and replacement of keys. It includes cryptographic protocol design, ...

'' – getting keys securely to thousands of crypto boxes in the field, perhaps the most challenging part of any encryption system. One NSA goal is benign fill (technology for distributing keys in a way that the humans never have access to plaintext key). * ''Investigative access'' – making sure encrypted communications are accessible to the U.S. Government. While few would argue with the need for the government to access its own internal communications, the NSA

Clipper chip The Clipper chip was a chipset that was developed and promoted by the United States National Security Agency (NSA) as an encryption device that secured "voice and data messages" with a built-in backdoor that was intended to "allow Federal, State, ...

proposal to extend this key escrow requirement to public use of cryptography was highly controversial. * ''

TEMPEST Tempest is a synonym for a storm. '' The Tempest'' is a play by William Shakespeare. Tempest or The Tempest may also refer to: Arts and entertainment Films * ''The Tempest'' (1908 film), a British silent film * ''The Tempest'' (1911 film), a ...

'' – protecting

from compromise by electronic, acoustic or other emanations. * ''

Tamper resistance Tamperproofing, conceptually, is a methodology used to hinder, deter or detect unauthorised access to a device or circumvention of a security system. Since any device or system can be foiled by a person with sufficient knowledge, equipment, and ti ...

tamper-evident Tamper-evident describes a device or process that makes unauthorized access to the protected object easily detected. Seals, markings, or other techniques may be tamper indicating. Tampering Tampering involves the deliberate altering or adultera ...

self-destruct A self-destruct is a mechanism that can cause an object to destroy itself or render itself inoperable after a predefined set of circumstances has occurred. Self-destruct mechanisms are typically found on devices and systems where malfunction could ...

'' – ensuring security even if encryption systems are physically accessed without authorization or are captured. * Meeting military specifications for size, weight, power consumption,

MTBF Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a mechanical or electronic system during normal system operation. MTBF can be calculated as the arithmetic mean (average) time between failures of a syst ...

and ruggedness to fit in mobile platforms. * ''

Electromagnetic pulse An electromagnetic pulse (EMP), also a transient electromagnetic disturbance (TED), is a brief burst of electromagnetic energy. Depending upon the source, the origin of an EMP can be natural or artificial, and can occur as an electromagnetic fie ...

hardening'' – protecting against

nuclear explosion A nuclear explosion is an explosion that occurs as a result of the rapid release of energy from a high-speed nuclear reaction. The driving reaction may be nuclear fission or nuclear fusion or a multi-stage cascading combination of the two, t ...

effects, particularly

electromagnetic pulse An electromagnetic pulse (EMP), also a transient electromagnetic disturbance (TED), is a brief burst of electromagnetic energy. Depending upon the source, the origin of an EMP can be natural or artificial, and can occur as an electromagnetic fie ...

. * Ensuring compatibility with military and commercial communication standards. * Controlling cost – making sure encryption is affordable so units that need it have it. There are many costs beyond the initial purchase price, including the manpower to operate and maintain the systems and to ensure their security and the cost of key distribution. * Enabling secure communication with NATO, allied and coalition forces without compromising secret methods.

Five generations of NSA encryption

The large number of encryption systems that NSA has developed in its half century of operation can be grouped into five generations (decades given are very approximate):

First generation: electromechanical

First generation NSA systems were introduced in the 1950s and were built on the legacy of NSA's

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

predecessors and used rotor machines derived from the

SIGABA In the history of cryptography, the ECM Mark II was a cipher machine used by the United States for message encryption from World War II until the 1950s. The machine was also known as the SIGABA or Converter M-134 by the Army, or CSP-888/889 by th ...

design for most high level encryption; for example, the

KL-7 The TSEC/KL-7, also known as Adonis was an off-line non-reciprocal rotor encryption machine.

. Key distribution involved distribution of paper key lists that described the rotor arrangements, to be changed each day (the ''

cryptoperiod A cryptoperiod is the time span during which a specific key (cryptography), cryptographic key is authorized for use. Common government guidelines range from 1 to 3 years for asymmetric cryptography, and 1 day to 7 days for symmetric cipher traffic ...

'') at midnight,

GMT Greenwich Mean Time (GMT) is the mean solar time at the Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being calculated from noon; as a cons ...

. The highest level traffic was sent using one-time tape systems, including the British 5-UCO, that required vast amounts of paper tape keying material.

Second generation: vacuum tubes

Second generation systems (1970s) were all electronic designs based on

s and transformer logic. Algorithms appear to be based on

linear-feedback shift register In computing, a linear-feedback shift register (LFSR) is a shift register whose input bit is a linear function of its previous state. The most commonly used linear function of single bits is exclusive-or (XOR). Thus, an LFSR is most often a sh ...

s, perhaps with some non-linear elements thrown in to make them more difficult to cryptanalyze. Keys were loaded by placing a

in a locked reader on the front panel.Melville Klein, "Securing Record Communications: The TSEC/KW-26", 2003, NSA brochure, p. 4
(PDF)
/ref> The cryptoperiod was still usually one day. These systems were introduced in the late 1960s and stayed in use until the mid-1980s. They required a great deal of care and maintenance, but were not vulnerable to EMP. The discovery of the Walker spy ring provided an impetus for their retirement, along with remaining first generation systems.

Third generation: integrated circuits

Third generation systems (1980s) were transistorized and based on

integrated circuit An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...

s and likely used stronger algorithms. They were smaller and more reliable. Field maintenance was often limited to running a diagnostic mode and replacing a complete bad unit with a spare, the defective box being sent to a depot for repair. Keys were loaded through a connector on the front panel. NSA adopted the same type of connector that the military used for field radio handsets as its fill connector. Keys were initially distributed as strips of

punched paper tape Five- and eight-hole punched paper tape Paper tape reader on the Harwell computer with a small piece of five-hole tape connected in a circle – creating a physical program loop Punched tape or perforated paper tape is a form of data storage ...

that could be pulled through a hand held reader ( KOI-18) connected to the fill port. Other, portable electronic

fill device A fill device or key loader is a module used to load cryptographic keys into electronic encryption machines. Fill devices are usually hand held and electronic ones are battery operated. Older mechanical encryption systems, such as rotor mach ...

s (

KYK-13 The KYK-13 Electronic Transfer Device is a common fill device designed by the United States National Security Agency for the transfer and loading of cryptographic keys with their corresponding check word. The KYK-13 is battery powered and uses the ...

, etc.) were available as well.

Fourth generation: electronic key distribution

Fourth generation systems (1990s) use more commercial packaging and electronic key distribution. Integrated circuit technology allowed backward compatibility with third generation systems.

Security token A security token is a peripheral device used to gain access to an electronically restricted resource. The token is used in addition to or in place of a password. It acts like an electronic key to access something. Examples of security tokens incl ...

s, such as the

KSD-64 The KSD-64 Crypto Ignition Key (CIK) is an NSA-developed EEPROM chip packed in a plastic case that looks like a toy key. The model number is due to its storage capacity — 64 kibibits (65,536bits, or 8KiB), enough to store multiple e ...

crypto ignition key (CIK) were introduced. Secret splitting technology allows encryptors and CIKs to be treated as unclassified when they were separated. Later the

Fortezza Fortezza is an information security system that uses the Fortezza Crypto Card, a PC Card-based security token. It was developed for the U.S. government's Clipper chip project and has been used by the U.S. Government in various applications. Ea ...

card, originally introduced as part of the controversial

proposal, were employed as tokens. Cryptoperiods were much longer, at least as far as the user was concerned. Users of secure telephones like the

STU-III STU-III (Secure Telephone Unit - third generation) is a family of secure telephones introduced in 1987 by the NSA for use by the United States government, its contractors, and its allies. STU-III desk units look much like typical office telephone ...

only have to call a special phone number once a year to have their encryption updated. Public key methods (

FIREFLY The Lampyridae are a family of elateroid beetles with more than 2,000 described species, many of which are light-emitting. They are soft-bodied beetles commonly called fireflies, lightning bugs, or glowworms for their conspicuous production ...

) were introduced for electronic key management (

EKMS The Electronic Key Management System (EKMS) is a United States National Security Agency led program responsible for Communications Security ( COMSEC) key management, accounting, and distribution. Specifically, EKMS generates and distributes elect ...

). Keys could now be generated by individual commands instead of coming from NSA by courier. A common handheld fill device (the

AN/CYZ-10 A fill device or key loader is a module used to load cryptographic keys into electronic encryption machines. Fill devices are usually hand held and electronic ones are battery operated. Older mechanical encryption systems, such as rotor machin ...

) was introduced to replace the plethora of devices used to load keys on the many third generation systems that were still widely used. Encryption support was provided for commercial standards such as

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

, IP (originally developed by DOD's ARPA), and optical fiber multiplexing. Classified networks, such as

SIPRNet The Secure Internet Protocol Router Network (SIPRNet) is "a system of interconnected computer networks used by the U.S. Department of Defense and the U.S. Department of State to transmit classified information (up to and including information cla ...

(Secret Internet Protocol Router Network) and

JWICS The Joint Worldwide Intelligence Communication System (JWICS, ) is the United States Department of Defense's secure intranet system that houses top secret and sensitive compartmented information. JWICS superseded the earlier DSNET2 and DSNET3, th ...

(Joint Worldwide Intelligence Communications System), were built using commercial

Internet The Internet (or internet) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a '' network of networks'' that consists of private, pub ...

technology with secure communications links between "enclaves" where classified data was processed. Care had to be taken to ensure that there were no insecure connections between the classified networks and the public

Fifth generation: network-centric systems

In the twenty-first century, communication is increasingly based on computer networking. Encryption is just one aspect of protecting sensitive information on such systems, and far from the most challenging aspect. NSA's role will increasingly be to provide guidance to commercial firms designing systems for government use.

HAIPE A High Assurance Internet Protocol Encryptor (HAIPE) is a Type 1 encryption device that complies with the National Security Agency's HAIPE IS (formerly the HAIPIS, the High Assurance Internet Protocol Interoperability Specification). The cryptogr ...

solutions are examples of this type of product (e.g.
KG-245A
an
KG-250
. Other agencies, particularly

NIST The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical sci ...

, have taken on the role of supporting security for commercial and sensitive but unclassified applications. NSA's certification of the unclassified NIST-selected AES algorithm for classified use "in NSA approved systems" suggests that, in the future, NSA may use more non-classified algorithms. The KG-245A and KG-250 use both classified and unclassified algorithms. The NSA Information Assurance Directorate is leading the Department of Defense

Cryptographic Modernization Program The Cryptographic Modernization Program is a Department of Defense directed, NSA Information Assurance Directorate led effort to transform and modernize Information Assurance capabilities for the 21st century. It has three phases: *Replacement- Al ...

, an effort to transform and modernize Information Assurance capabilities for the 21st century. It has three phases: * Replacement – All at risk devices to be replaced. * Modernization – Integrate modular programmable/embedded crypto solutions. * Transformation – Be compliant to Global Information Grid/NetCentric requirements. NSA has helped develop several major standards for secure communication: the ''Future Narrow Band Digital Terminal (

FNBDT The Secure Communications Interoperability Protocol (SCIP) is a US standard for secure voice and data communication, foone-to-one connections, not packet-switched networks. SCIP derived from the US Government Future Narrowband Digital Terminal ( ...

)'' for voice communications, ''High Assurance Internet Protocol Interoperability Encryption- Interoperability Specification (

)'' for computer networking and

Suite B NSA Suite B Cryptography was a set of cryptographic algorithms Promulgation, promulgated by the National Security Agency as part of its Cryptographic Modernization Program. It was to serve as an interoperable cryptographic base for both unclassi ...

encryption algorithms.

NSA encryption by type of application

The large number of encryption systems that NSA has developed can be grouped by application:

Record traffic encryption

During

, written messages (known as record traffic) were encrypted off line on special, and highly secret,

rotor machine In cryptography, a rotor machine is an electro-mechanical stream cipher device used for encrypting and decrypting messages. Rotor machines were the cryptographic state-of-the-art for much of the 20th century; they were in widespread use in the 19 ...

s and then transmitted in five letter code groups using

Morse code Morse code is a method used in telecommunication to encode text characters as standardized sequences of two different signal durations, called ''dots'' and ''dashes'', or ''dits'' and ''dahs''. Morse code is named after Samuel Morse, one of ...

teletypewriter A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point (telecommunications), point-to-point and point- ...

circuits, to be decrypted off-line by similar machines at the other end. The

rotor machine, developed during this era continued to be used until the mid-1950s, when it was replaced by the

KL-7 The TSEC/KL-7, also known as Adonis was an off-line non-reciprocal rotor encryption machine.

, which had more rotors. The

KW-26 The TSEC/KW-26, code named ROMULUS, (in 1966 the machine based encryption system was not code-named "Romulus," rather the code-name was "Orion," at least in the US Army's variant) was an encryption system used by the U.S. Government and, later, ...

ROMULUS was a second generation encryption system in wide use that could be inserted into teletypewriter circuits so traffic was encrypted and decrypted automatically. It used electronic

shift registers A shift register is a type of digital circuit using a cascade of flip-flops where the output of one flip-flop is connected to the input of the next. They share a single clock signal, which causes the data stored in the system to shift from one lo ...

instead of rotors and became very popular (for a COMSEC device of its era), with over 14,000 units produced. It was replaced in the 1980s by the more compact

KG-84 The KG-84A and KG-84C are encryption devices developed by the U.S. National Security Agency (NSA) to ensure secure transmission of digital data. The KG-84C is a Dedicated Loop Encryption Device (DLED), and both devices are General-Purpose Telegra ...

, which in turn was superseded by the KG-84-interoperable

KIV-7 The KIV-7 is a National Security Agency Type-1, single-channel encryptor originally designed in the mid-1990s by AlliedSignal Corporation to meet the demand for secure data communications from personal computers (PC), workstations, and FAXs. It h ...

Fleet broadcast

U.S. Navy ships traditionally avoid using their radios to prevent adversaries from locating them by

direction finding Direction finding (DF), or radio direction finding (RDF), isin accordance with International Telecommunication Union (ITU)defined as radio location that uses the reception of radio waves to determine the direction in which a radio station ...

. The Navy also needs to maintain traffic security, so it has radio stations constantly broadcasting a stream of coded messages. During and after World War II, Navy ships copied these ''fleet broadcasts'' and used specialized ''

call sign In broadcasting and radio communications, a call sign (also known as a call name or call letters—and historically as a call signal—or abbreviated as a call) is a unique identifier for a transmitter station. A call sign can be formally assigne ...

encryption'' devices to figure out which messages were intended for them. The messages would then be decoded off line using

KL-7 The TSEC/KL-7, also known as Adonis was an off-line non-reciprocal rotor encryption machine.

equipment. The second generation

KW-37 The KW-37, code named JASON, was an encryption system developed In the 1950s by the U.S. National Security Agency to protect fleet broadcasts of the U.S. Navy. Naval doctrine calls for warships at sea to maintain radio silence to the maximum ext ...

automated monitoring of the fleet broadcast by connecting in line between the radio receiver and a

teleprinter A teleprinter (teletypewriter, teletype or TTY) is an electromechanical device that can be used to send and receive typed messages through various communications channels, in both point-to-point and point-to-multipoint configurations. Initia ...

. It, in turn, was replaced by the more compact and reliable third generation KW-46.

Strategic forces

NSA has the responsibility to protect the command and control systems for nuclear forces. The KG-3X series is used in the U.S. government's ''Minimum Essential Emergency Communications Network'' and the ''Fixed Submarine Broadcast System'' used for transmission of emergency action messages for nuclear and national command and control of U.S. strategic forces. The Navy is replacing the KG-38 used in

nuclear submarine A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. Nuclear submarines have considerable performance advantages over "conventional" (typically diesel-electric) submarines. Nuclear propulsion, ...

s with KOV-17 circuit modules incorporated in new long-wave receivers, based on commercial VME packaging. In 2004, the U.S. Air Force awarded contracts for the initial system development and demonstration (SDD) phase of a program to update these legacy generation systems used on aircraft.

Trunk encryption

Modern communication systems

multiplex Multiplex may refer to: * Multiplex (automobile), a former American car make * Multiplex (comics), a DC comic book supervillain * Multiplex (company), a global contracting and development company * Multiplex (assay), a biological assay which measu ...

many signals into wideband data streams that are transmitted over

optical fiber An optical fiber, or optical fibre in Commonwealth English, is a flexible, transparent fiber made by drawing glass (silica) or plastic to a diameter slightly thicker than that of a human hair. Optical fibers are used most often as a means to ...

coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...

microwave Microwave is a form of electromagnetic radiation with wavelengths ranging from about one meter to one millimeter corresponding to frequencies between 300 MHz and 300 GHz respectively. Different sources define different frequency ran ...

relay, and

communication satellite A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth. C ...

s. These wide-band circuits require very fast encryption systems. The

WALBURN Walburn is a hamlet and civil parishes in England, civil parish in the Richmondshire district of North Yorkshire, England. It is located in lower Swaledale, south-west of Richmond, North Yorkshire, Richmond. The population of the parish was es ...

family ( KG-81, KG-94/ 194, KG-94A/ 194A, KG-95) of equipment consists of high-speed bulk encryption devices used primarily for microwave trunks, high-speed land-line circuits, video teleconferencing, and T-1 satellite channels. Another example is the KG-189, which support

SONET Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diode ...

optical standards up to 2.5 Gbit/s. Digital Data encryptors such as

family which includes the TSEC/

, TSEC/

A and TSEC/ KG-82, TSEC/

A and TSEC/

C, also the

Voice encryption

True voice encryption (as opposed to less secure

scrambler In telecommunications, a scrambler is a device that transposes or inverts signals or otherwise encodes a message at the sender's side to make the message unintelligible at a receiver not equipped with an appropriately set descrambling device. Wher ...

technology) was pioneered during World War II with the 50-ton

SIGSALY SIGSALY (also known as the X System, Project X, Ciphony I, and the Green Hornet) was a secure speech system used in World War II for the highest-level Allied communications. It pioneered a number of digital communications concepts, including the ...

, used to protect the very highest level communications. It did not become practical for widespread use until reasonable compact speech encoders became possible in the mid-1960s. The first tactical secure voice equipment was the NESTOR family, used with limited success during the Vietnam war. Other NSA voice systems include:A History of U.S. Communications Security; the David G. Boak Lectures
National Security Agency (NSA), Volumes I, 1973, Volumes II 1981, partially released 2008, additional portions declassified October 14, 2015 * STU I and STU II – These systems were expensive and cumbersome and were generally limited to the highest levels of command *

– These telephone sets operated over ordinary telephone lines and featured the use of security tokens and

public key cryptography Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic alg ...

, making them much more user friendly. They were very popular as a result. Used since the 1980s, this device is rapidly being phased out, and will no longer be supported in the near future. * 1910 Terminal – Made by a multiple of manufacturers, this device is mostly used as a secure modem. Like the STU-III, new technology has largely eclipsed this device, and it is no longer widely used. * HY-2 a vocoder for long haul circuits designed to work with the KG-13 key generator. *

Secure Terminal Equipment Secure Terminal Equipment (STE) is the U.S. government's current (), encrypted telephone communications system for wired or "landline" communications. STE is designed to use ISDN telephone lines which offer higher speeds of up to 128 kbit/s ...

(STE) – This system is intended to replace STU-III. It uses wide-

bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...

voice transmitted over

ISDN Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the digitalised circuits of the public switched telephone network. Wo ...

lines. There is also a version which will communicate over a PSTN (Public Switched Telephone Network) line. It can communicate with STU-III phones and can be upgraded for FNBDT compatibility. *

Sectéra Secure Module Sectéra is a family of secure voice and data communications products produced by General Dynamics Mission Systems which are approved by the United States National Security Agency. Devices can use either National Institute of Standards and Tech ...

– A module that connects to the back of a commercial off the shelf cellular phone. It uses AES or SCIP for encryption. * OMNI – The OMNI terminal, made by L3 Communications, is another replacement for STU-IIIs. This device uses the FNBDT key and is used to securely send voice and data over the PSTN and ISDN communication systems. *

VINSON VINSON is a family of voice encryption devices used by U.S. and allied military and law enforcement, based on the NSA's classified Suite A SAVILLE encryption algorithm and 16 kbit/s CVSD audio compression. It replaces the Vietnam War-era N ...

A series of systems for tactical voice encryption including the KY-57 man portable unit and

KY-58 The VINSON KY-58 is a secure voice module primarily used to encrypt radio communication to and from military aircraft and other tactical vehicles. It is employed by U.S. Military Joint Services, NATO and some law enforcement agencies. It is des ...

for aircraft * HAVE QUICK and

SINCGARS Single Channel Ground and Airborne Radio System (SINCGARS) is a Combat-net radio (CNR) used by U.S. and allied military forces. The CNR network is designed around three systems: SINCGARS, the high frequency (HF) radio, and the SC tactical sate ...

use NSA-supplied sequence generators to provide secure

frequency hopping Frequency-hopping spread spectrum (FHSS) is a method of transmitting radio signals by rapidly changing the carrier frequency among many distinct frequencies occupying a large spectral band. The changes are controlled by a code known to both tra ...

* Future Narrowband Digital Terminal (FNBDT) – Now referred to as the "Secure Communications Interoperability Protocol" ( SCIP), the FNBDT is a replacement for the wide-band STE, which uses narrow-bandwidth communications channels like

cellular telephone A mobile phone, cellular phone, cell phone, cellphone, handphone, hand phone or pocket phone, sometimes shortened to simply mobile, cell, or just phone, is a portable telephone that can make and receive telephone call, calls over a radio freq ...

circuits, rather than ISDN lines. The FNBDT/SCIP operates on the application layer of the ISO/OSI Reference Model, meaning that it can be used on top of different types of connections, regardless of the establishment method. It negotiates with the unit at the other end, much like a dial-up

modem A modulator-demodulator or modem is a computer hardware device that converts data from a digital format into a format suitable for an analog transmission medium such as telephone or radio. A modem transmits data by Modulation#Digital modulati ...

. * Secure Iridium – NSA helped add encryption to the Iridium commercial mobile phones after it rescued the bankrupt

Iridium Iridium is a chemical element with the symbol Ir and atomic number 77. A very hard, brittle, silvery-white transition metal of the platinum group, it is considered the second-densest naturally occurring metal (after osmium) with a density of ...

. * Fishbowl – In 2012, NSA introduced an Enterprise Mobility Architecture intended to provide a secure VoIP capability using commercial grade products and an Android-based mobile phone called Fishbowl that allows classified communications over commercial wireless networks. The operational complexity of secure voice played a role in the

September 11, 2001 attacks The September 11 attacks, commonly known as 9/11, were four coordinated suicide terrorist attacks carried out by al-Qaeda against the United States on Tuesday, September 11, 2001. That morning, nineteen terrorists hijacked four commercial ...

on the United States. According to the 911 Commission, an effective U.S. response was hindered by an inability to set up a secure phone link between the National Military Command Center and the

Federal Aviation Administration The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...

personnel who were dealing with the hijackings. ''See''

Communication during the September 11, 2001 attacks Communication problems and successes played an important role during the September 11 attacks in 2001 and their aftermath. Systems were variously destroyed or overwhelmed by loads greater than they were designed to carry, or failed to operate a ...

Internet

NSA has approved a variety of devices for securing

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP h ...

communications. These have been used to secure the Secret Internet Protocol Router Network (

), among other uses. The first commercial network layer encryption device was the Motorola Network Encryption System (NES). The system used the SP3 and KMP protocols defined by the NSA Secure Data Network System (SDNS) and were the direct precursors to

IPsec In computing, Internet Protocol Security (IPsec) is a secure network protocol suite that authenticates and encrypts packets of data to provide secure encrypted communication between two computers over an Internet Protocol network. It is used in ...

. The NES was built in a three part architecture that used a small cryptographic security kernel to separate the trusted and untrusted network protocol stacks. The SDNS program defined a Message Security Protocol (MSP) that was built on the use X.509 defined certificates. The first NSA hardware built for this application was the BBN Safekeeper. The Message Security Protocol was a successor to the IETF Privacy Enhance Mail (PEM) protocol. The BBN Safekeeper provided a high degree of tamper resistance and was one of the first devices used by commercial PKI companies.

Field authentication

NSA still supports simple paper encryption and authentication systems for field use such as

DRYAD A dryad (; el, Δρυάδες, ''sing''.: ) is a tree nymph or tree spirit in Greek mythology. ''Drys'' (δρῦς) signifies " oak" in Greek, and dryads were originally considered the nymphs of oak trees specifically, but the term has evolved t ...

Public systems

NSA has participated in the development of several encryption systems for public use. These include: *

– a set of

public key Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic al ...

algorithm standards based on

elliptic curve cryptography Elliptic-curve cryptography (ECC) is an approach to public-key cryptography based on the algebraic structure of elliptic curves over finite fields. ECC allows smaller keys compared to non-EC cryptography (based on plain Galois fields) to provide e ...

. *

Advanced Encryption Standard The Advanced Encryption Standard (AES), also known by its original name Rijndael (), is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001. AES is a variant ...

(AES) – an encryption algorithm, selected by

after a public competition. In 2003, NSA certified AES for Type 1 use in some NSA-approved systems. *

Secure Hash Algorithm The Secure Hash Algorithms are a family of cryptographic hash functions published by the National Institute of Standards and Technology (NIST) as a U.S. Federal Information Processing Standard (FIPS), including: * SHA-0: A retronym applied to th ...

– a widely used family of

hash algorithm A hash function is any function that can be used to map data of arbitrary size to fixed-size values. The values returned by a hash function are called ''hash values'', ''hash codes'', ''digests'', or simply ''hashes''. The values are usually ...

s developed by NSA based on earlier designs by

Ron Rivest Ronald Linn Rivest (; born May 6, 1947) is a cryptographer and an Institute Professor at MIT. He is a member of MIT's Department of Electrical Engineering and Computer Science (EECS) and a member of MIT's Computer Science and Artificial Intell ...

. *

Digital Signature Algorithm The Digital Signature Algorithm (DSA) is a public-key cryptosystem and Federal Information Processing Standard for digital signatures, based on the mathematical concept of modular exponentiation and the discrete logarithm problem. DSA is a variant ...

Data Encryption Standard The Data Encryption Standard (DES ) is a symmetric-key algorithm for the encryption of digital data. Although its short key length of 56 bits makes it too insecure for modern applications, it has been highly influential in the advancement of cry ...

(DES) * Skipjack – the cipher developed for Clipper and finally published in 1998. *

– a controversial failure that convinced NSA that it was advisable to stay out of the public arena. *

Security-Enhanced Linux Security-Enhanced Linux (SELinux) is a Linux kernel security module that provides a mechanism for supporting access control security policies, including mandatory access controls (MAC). SELinux is a set of kernel modifications and user-space ...

– not strictly an encryption system, but a recognition that in the 21st century,

operating system An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also in ...

improvements are more vital to information security than better

cipher In cryptography, a cipher (or cypher) is an algorithm for performing encryption or decryption—a series of well-defined steps that can be followed as a procedure. An alternative, less common term is ''encipherment''. To encipher or encode i ...

s. * The

Speck Speck can refer to a number of European cured pork products, typically salted and air-cured and often lightly smoked but not cooked. In Germany, speck is pickled pork fat with or without some meat in it. Throughout much of the rest of Europe a ...

and

Simon Simon may refer to: People * Simon (given name), including a list of people and fictional characters with the given name Simon * Simon (surname), including a list of people with the surname Simon * Eugène Simon, French naturalist and the genus ...

light-weight Block ciphers, published in 2013.

References

Sources

NSA official site

Jerry Proc Crypto machine page

Brooke Clarke Crypto machines site
{{Webarchive, url=https://web.archive.org/web/20160304024849/http://www.pacificsites.com/~brooke/I/CryptoM.shtml , date=2016-03-04

A History of U.S. Communications Security; the David G. Boak Lectures, National Security Agency (NSA), Volumes I, 1973, Volumes II 1981, partially released 2008, additional portions declassified October 14, 2015
National Security Agency *