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Glossary of crypto terminology

AES   Advanced Encryption Standard

AIVD   Centrale Inlichtingen- en Veiligheidsdienst
Dutch Intelligence and Security Agency. (Website) (Other)

ANMCC   Alternate National Military Command Center
Backup command center of the Pentagon's NMCC, also the backup terminal of the Hotline (DCL), located in Raven Rock Mountain. (More...) (Wikipedia)

ASCII   American Standard Code for Information Interchange
Character encoding scheme, based on the ordering of the English alphabet, using 7-bits to describe each letter. Commonly used to represent text in computers, communication equipment and other devices that use text. Most modern encoding schemes are based on extended ASCII. (More...) (Wikipedia)

AUTOKO   Automatisiertes Kommunikationssystem 90
Wide area communications system used by the German Army (Bundeswehr). AutoKo I was introduced on 1977, followed in 1985 by AutoKo II and finally in 1995 by AutoKo 90. AUTOKO was gradually phased out from 2010 onwards. Examples of AutoKo equipment are the Siemens CTE-020, the Elcrovox 1/4 and the ANT KWF. (Wikipedia)

AUTOVON   Automatic Voice Network
Military phone system that was built in the US in 1963. Designed to survive nuclear attacks, it allowed non-secure voice calls with precedence (piority override). (More...) (Wikipedia)

BAUDOT   Method for sending text-based messages over wire or radio links, using a 5-bit digital code. Based on the ITA2 standard. (More...) (Wikipedia)

BID   British Inter Departmental
Identification used for equipment used by the British Armed Forces and various Government departments. BID is sometimes erroneously explained as British Industrial Development (even by people in the know). Each device is identified by the abbreviation 'BID' followed by a '/' and a number, e.g. BID/950. The authority for BID designators are the Communications-Electronics Security Group (CESG) who are part of GCHQ.

BP   Bletchley Park
An estate in the town of Bletchley (UK) that was the UK's main code breaking site during WWII. It is here where, amongst others, the German Enigma codes were broken. (More...) (Wikipedia) (Website)

BND   Bundes-Nachrichten-Dienst
German intelligence service. (Wikipedia) (Other)

BSC   British Security Coordination
Covert organisation set up in New York (US) by the British Intelligence Service MI6 in May 1940 by William Stephenson upon the authorisation of Prime Minister Winston Churchill. Its purpose was to prevent sabotage against British interests in the Americas, investigate enemy activities and mobilise pro-British opnion in pre-war America. (Wikipedia)

CELP   Codebook Excited Linear Prediction
Method for digitizing human speech, also known as a vocoder. Improved version of LPC encoding. CELP is a US Government standard that can be used at 4800 baud.

CESG   Communications-Electronics Security Group
Information security arm of GCHQ. Also the National Technical Authority for Information Assurance within the UK. GESG is also responsible for assigning the so-called 'BID' designators for equipment. (Website)

CEROFF   Cipher Equipment Rapid Off-Line
Code name of a NATO evaluation in 1974 to find a replacement for the ageing KL-7 cipher machine. Examples of CEROFF compatible equipment are Aroflex, RACE (KL-51) and Picoflex.

CFB   Cipher Feedback
A block cipher mode that enhanced ECB mode by chaining together blocks of cipher text it produces, and operating on plaintext segments of variable length, less than or equal to the block length.

CIA   Central Intelligence Agency
(Wikipedia) (Website) (Other)

CIK   Crypto Ignition Key
A physical token (usually an electronic device) used to store, transport and activate the cryptographic keys of electronic cipher machines. (Wikipedia)

Cipher   The algorithm used for the encryption and/or decryption of information. In common language, 'cipher' is also used to refer to an encryption message, also known as 'code'. (Wikipedia)

Cold War   State of political and military tension in the period after WWII (1947-1991), between the Western Block (US, Europe, NATO) and the Eastern Block (Soviet Union and its Warsaw Pact allies). (Wikipedia)

COMSEC   Communications Security

Covert Operation   General expression for a 'clandestine operation' legally carried by, or on behalf of, a government body. In the US, covert operations are typically carried out by the CIA. The expression 'covert' is sometime expanded to include secret service work, VIP protection, surveillance and eavesdropping.

Crib   Known or suspected part of the plain text

Cryptanalysis   Codebreaking
The study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. (Wikipedia)

Crypto   Cryptography

Cryptography   Common expression to refer to cryptographic equipment (cipher machines) and/or the process of encrypting and decrypting information. (Wikipedia)

CTAK   Cipher Text Auto-Key
Cryptographic logic that uses previous cipher text to generate a key stream. (Depricated terminology, superceeded by CFB)

DCL   Direct Communications Link
Official name of the Washington-Moscow Hotline. (More...) (Wikipedia)

DES   Data Encryption Standard
DES was an important encryption algorithm for the protection of electronic data, developed by IBM in the US, in the early 1970s. After a small modification, it was approved by the NSA and the US national Bureau of Standards (NBS) for use as an official FIPS in 1977. DES has a key length of 56 bits. By today's standards DES is no longer considered secure enough for most applications and has been superceeded by Triple DES and AES. (Wikipedia)

DF   Direction Finding
When a radio transmitter is on the air for a sufficiently long period of time, it is possible to trace its position. This is often done by using directional antennas and plotting the angle from two or three intercept stations on a map. It is also possible to a doppler-based antenna system for mobile searches, and to use a simple field-streng indicator to find transmitters in close proximity.

DNS   Direct NICS Subscriber
Direct subscriber of the NATO Integrated Communications System (NICS).

DNVT   Digital Non-secure Voice Terminal
Unit for unencrypted digital voice communication (phone).

DSVT   Digital Subscriber Voice Terminal
Unit for encrypted (secure) voice communication (phone), such as the American KY-68. Interoperable (in non-secure mode) with the DNVT.

DTMF   Dual Tone Multy-Frequency
In-band tone system used for telecommunication signalling over analog telephone lines. The system uses 8 different tones, two of which are sent simultaneously. It is mainly used in push-button phones to produce the numbers 0-9 plus '*" and '#'. Some keypads are capable of sending A, B, C and D as well. (Wikipedia)

DVL   Direct Voice Link
Voice communication link, running on the same network, but not part of, the Washington-Moscow Hotline.

ECB   Electronic Codebook
A block cipher mode in which a plaintext block is used directly as input to the encryption algorithm and the resultant output block is used directly as cipher text.

ECCM   Electronic Counter Counter Measures
Equipment used in secure communications (COMSEC) to protect against counter measures, such as eavesdropping, interception, direction finding, etc. Frequency Hopping (FH) is an example of ECCM.

EKMS   Electronic Key Management System
NSA-endorsed program for COMSEC key management. (Wikipedia) (Other)

EMU   Electronic Message Unit

ERF   Electronic Remote fill

FH   Frequency Hopping
Method for quicky changing the frequency (channel) during a transmission in a seemingly random order. This is done as an electronic counter counter measure (ECCM), to protect the conversation against eavesdropping and interception by the enemy.

Fill   Key-fill

Filler   Key fill device

FIPS   Federal Information Processing Standard

FK   Fill Key

FNBDT   Future Narrow Band Digital Terminal
Later renamed to Secure Communications Interoperability Protocol (SCIP)

GC&CS   Government Code and Cypher School
British code breaking organisation during WWII. Now called GCHQ.

GCHQ   Government Communications Headquarters
British intelligence agency. (More...) (Wikipedia) (Website) (Other)

HMGCC   Her Majesty's Government Communications Centre
British development centre for secure communications, hardware and software. Mainly aimed at HM Government use, both in the UK and overseas. Also known as Hanslope Park. (Wikipedia) (Website)

ICOM   Integrated Communications Security

INFOSEC   Information Security

Iron Curtain   Ideological and physical border that divided Europe into two separate areas from the end of WWII to the end of the Cold War (1945-1991). To the west of this border was the free Western Block (NATO and West-European countries). To the east of the border was the Soviet Union and its Soviet-controlled satellites of the Warsaw Pact. (Wikipedia)

ISK   Intelligence Service Knox
Also known as Illicit Services Knox. During WWII, ISK was a special section at Bletchley Park (BP) where the Enigma cipher of the German Abwehr was broken. The section was led by codebreaker Dilly Knox and was established after breaking the Enigma G in October 1941. After Knox died in February 1943, Peter Twinn became in charge. By the end of the war, ISK had intercepted and decrypted 140,800 Abwehr messages.

ISOS   Intelligence Services Oliver Strachey
Also known as Illicit Services Oliver Strachey. During WWII, ISOS was a special section at Bletchley Park (BP) where the hand ciphers of the German Secret Service were broken and where the intelligence derived from the broken messages was handled. The section was led by Oliver Strachey.

IVSN   Initial Voice Switched Network
Analog switched telephone network developed by NATO in the mid-1970s. It was used for unclassified voice calls throughout NATO and was discontinued in 2005. (More...)

KAK   Key-auto-key
Cryptographic logic using a previous key to produce a key. (Depricated terminology, superceeded by OFB)

KDC   Key Distribution Center

KEK   Key Encryption Key
Special cryptographic key used to send new keys over-the-air (OTAR).

Key   A key is a piece of information (parameter) that determines the functional output of a cryptographic algorithm (cipher). Without the key, the algorithm can not be used. (Wikipedia)

Key-fill   Loading of a crypto-device with key material. Commonly achieved by using a so-caller key fill device (or: filler) to distribute key material. (More...)

Key fill device   Device used for the distribution of cryptographic material (keys). The device is loaded by a Key Generator, and can dump its contents to a crypto-device or another key fill device. (More...)

LPC   Linear Predictive Coding
A method for digitizing human speech by analyzing and storing specific characteristics of it, in such a way that an intelligible signal can be reconstructed later. LPC-10E was a US Government standard that was used at 2400 baud on all STU-III terminals. (Wikipedia)

MERCS   Merchant Ship Crypto System
Code name of a NATO evaluation in 1975 to search for small portable text-based cryptographic devices. Examples of MERCS equipment are the hand-held PACE and the initial version of the portable Picoflex.


Mixer   A cipher machine based on the Vernam Cipher principle, adding a key-stream to the plain-text stream in order to obtain the cipher-text. The plain-text is derived from the cipher-text by adding the key-stream once again. The key-stream is often generated by a random number generator (OTP). With Teletype, the key-stream was often implemented as an OTT. (More...)

NATO   North Atlantic Treaty Organization
(Wikipedia) (Website)


NICS   NATO Integrated Communications System

NIST   National Institute of Standards and Technology
Non-regulatory body of the US Department of Commerce for the promotion and development of measurement science, standards and technology. From 1901 to 1988 known as the National Bureau of Standards (NBS). (Wikipedia)

NMCC   National Military Command Center
Command center of the Pentagon, responsible for operation, maintenance and testing of the Hotline (DCL). Also the primary terminal of the US side of the Hotline. Located at the Pentagon in Washington. (More...) (Wikipedia)

NRO   National Reconnaissance Office
Responsible for the design, building and operation of the spy satellites of the US government. Based in Chantilly, Virginia (USA). (Other) (Wikipedia)

NSA   National Security Agency
America's national cryptologic organisation, responsible for US information security. Home of the American codemakers and codebreakers. (More...) (Other) (Wikipedia) (Website)

OFB   Output feedback
a block cipher mode that modifies ECB mode to operate on plaintext segments of variable length lesss than or equal to the block length.

OSS   Office of Strategic Services
Clandestine US organisation for infiltration and sabotage activities during WWII. The predecessor of the current CIA.


OTAR   Over-The-Air Rekeying
Common expression for the method of updating encryption keys 'over the air' in a two-way radio system. It is sometimes called Over-The-Air Transfer (OTAT). (Wikipedia)

OTP   One-Time Pad
A truely random sequence of numbers or letters, used for the encryption and decription of a text,of which only two copies exist and that is only used once. Once the message is exchanged, the two copies of the OTP are destroyed. (More...) (Wikipedia)

OTT   One-Time Tape
Similar to OTP but based on the use of punched paper tape in combination with Teletype (TTY, Telex) machines. Cipher machines using OTT, are often called mixer machines. (More...)

RACE   Rapid Automatic Cryptographic Equipment
Acronym used for the NATO KL-51 cipher machine that was used for NATO CEROFF communication alongside the Philips Aroflex. RACE was manufactured by Standard Telefon og Kabelfabrik A/S in Norway.

RTTY   Radio Teletype
TTY over a radio link. (Wikipedia)

SC   Single Channel

SCIP   Secure Communications Interoperability Protocol
Universal communication protocol which doesn't depend on the bandwidth of the underlying channel. Existing US secure voice terminals are being replaced by SCIP or are being made SCIP-compatible. (More...)

SECAN   Military Committee Communications Security & Evaluation Agency (Washington)

SHAPE   Supreme Headquarters Allied Powers Europe
Headquarters of the Allied Command Operations (ACO), one of NATO's two strategic military commands. (Website)

SIGINT   Signals Intelligence
Intelligence-gathering by interception of signals. This can be communications (COMINT), other electronic signals (ELINT) or a combination of both. SIGINT is often related to encypted signals and may involve cryptanalysis. (Wikipedia)

SINCGARS   Single Ground and Airborne Radio System
Combat Radio Network used by the US Armed Forces and part of NATO. (More...) (Wikipedia)

SIS   Secret Intelligence Service

SOE   Special Operations Executive
British Special Forces active in clandestine operations behind enemy lines during WWII. (Wikipedia)

Soviet Union   The USSR, or Union of Soviet Socialist Republics, often abbreviated to Soviet Union, was a Marxist-Leninist federation of states on the Eurasian continent that existed between 1922 and 1991. It was controlled by the Communist Party with Moscow (Russia) as its capital.

Spread Spectrum   An electronic counter counter measure (ECCM), similar to Frequency Hopping but with much faster hopping over a wider range of channels, effectively using an entire band and resulting a 'noise'-style spectrum.

STE   Secure Terminal Equipment
A range of systems for secure voice and data communications over a variety of networks, including PSTN, ISDN and TRI-TAC. (More..)

STU   Secure Terminal Unit
Standard for secure voice and data conversations via standard analogue telephone networks, developed and maintained by the US National Security Agency (NSA). There are three generations of STU devices, known as STU-I, STU-II and STU-III. STU was later succeeded by Secure Terminal Equipment (STE).

TED   Trunk Encryption Device
Encryption device for bundled (multiplexed) data streams, generally consisting of voice and (computer) data.

TEMPEST   Codename, referring to (the study of) unwanted compromising emanations. This includes the emission of unintentional and unwanted intelligence-bearing signals. If such signals were intercepted and analyzed, they might disclose sensitive information. In cryptography, the interceptor might be able to reconstruct (part of) the plain text. (Wikipedia)

TROL   Tape Rotorless Off-Line
Code name for a NATO evaluation in 1962 in order to stimulate the development of rotor-less machines, based an an electronic key generator. TROL-developments were carried out, for example by Philips and STK.

TSK   Transmission Security Key
Encrypted data for creating an FH pattern.

TTY   Teletype
Method for sending written (printed) messages over a wire or radio link, using a 5-bit digital code, mostly ITA2 (Baudot-Murray). (Wikipedia)

Ultra   Top Scret Ultra
Ultra or Top Secret Ultra was the designation used by British military intelligence from 1941 onwards for signals intelligence derived from breaking high-level encrypted enemy radio and teleprinter communications at the Government Code & Cipher School (GC&CS) at Bletchley Park (BP). (Wikipedia)

Vernam Cipher   Method for obtaining the cipher-text from a plain-text and vice versa, by adding a key-stream, using module-2 addition (XOR). The process can be reversed by adding the key-stream once again, effectively resulting in a symmetric cipher. (More...) (Wikipedia)

Vocoder   Voice Coder, or Speech Digitizer
Method for converting (analogue) human voice signals into digital data, in such a way that it can be used for digital storage and/or transmission. Vocoders are also used to digitize speech before encryption.

WHCA   White House Communications Agency
Official communications agency of the White House. Also responsible for operating the secundary terminal of the US side of the Hotline (DCL). (Website) (Wikipedia)

WEU   Western European Union
Alliance of West-European countries, formed after WWII. Dissolved into NATO in 1949.

WP   Warsaw Pact
Collective defense treaty among eight communist states in Central and Eastern Europe, lead by the Soviet Union (USSR), that existed during the Cold War. The members were Albania, Bulgaria, Czechoslovakia, East-Germany (DDR), Hungary, Poland, Romania and the Soviet Union (USSR). (Wikipedia)

WU   WEU - Western European Union

TEK   Traffic Encryption Key
Cryptographic key used the encryption of messages (traffic).

WWII   World War II
Global war from 1939 to 1945 between two military alliances: the Allies and the Axis. It was the most widespread and probably also the most well-documented war in history. Also known as The Second World War and WW2. (Wikipedia)

XOR   Exclusive OR
Binary operation that produces a result if exactly one if it inputs is true. As this process can be reversed by applying it once again, it is often used in cryptography, e.g. in the Vernam Cipher. In mathematics, the XOR operation is called modulo-2 addition.

XX   Double-Cross System
The Double-Cross System, or XX System was a secret anti-espionage and deception operation of MI5 during WWII. Nazi spies in the UK and elsewhere were caught and turned, so that they could be used to feed false intelligence to the Germans. The operation was led by the Double-Cross Committee, also known as the XX Committee or the Twenty Committee. (Wikipedia)

ZEROIZE   General expression for deleting the cryptographic keys and other variables from an encryption device in case of a compromise or seizure.

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Crypto Museum. Last changed: Saturday, 13 May 2017 - 12:07 CET.
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