STU-II secure telephone desk set. Electronics were housed in a separate cabinet.
The STU-II (Standard Telephone Unit II) is a secure telephone developed by the U.S. National Security Agency. It permitted up to six users to have secure communications, on a time-shared (e.g.: rotating) basis. It was made by ITT Defense Communications, Nutley, New Jersey. An OEM partner was Northern Telecom.
According to information on display in 2005 at the NSA's National Cryptologic Museum, the STU-II was in use from the 1980s to the present. It uses the linear predictive coding algorithm LPC-10 at 2.4 kilobits/second to digitize voice, and the "Key Distribution Center" (KDC) for key management. The display also stated that the STU-II B is the standard narrow band secure telephone.
STU-II replaced the STU-I, KY-3 and the Navajo I. The last was a secure telephone in a briefcase, of which 110 were built in the 1980s for use by senior government officials when traveling. The Navaho I also used LPC-10.
The Enigma machine is a cipher device developed and used in the early- to mid-20th century to protect commercial, diplomatic, and military communication. It was employed extensively by Nazi Germany during World War II, in all branches of the German military. The Enigma machine was considered so secure that it was used to encipher the most top-secret messages.
Linear predictive coding (LPC) is a method used mostly in audio signal processing and speech processing for representing the spectral envelope of a digital signal of speech in compressed form, using the information of a linear predictive model.
Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for voice calls for the delivery of voice communication sessions over Internet Protocol (IP) networks, such as the Internet.
The Central Security Service (CSS) is a combat support agency of the United States Department of Defense which was established in 1972 to integrate the National Security Agency (NSA) and the Service Cryptologic Components (SCC) of the United States Armed Forces in the field of signals intelligence, cryptology, and information assurance at the tactical level. In 2002, the CSS had approximately 25,000 uniformed members. It is part of the United States Intelligence Community.
The National Cryptologic Museum (NCM) is an American museum of cryptologic history that is affiliated with the National Security Agency (NSA). The first public museum in the U.S. Intelligence Community, NCM is located in the former Colony Seven Motel, just two blocks from the NSA headquarters at Fort George G. Meade in Maryland. The motel was purchased, creating a buffer zone between the high security main buildings of the NSA and an adjacent highway. The museum opened to the public on December 16, 1993, and now hosts about 50,000 visitors annually from all over the world.
SIGSALY 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 first transmission of speech using pulse-code modulation.
STU-III 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 telephones, plug into a standard telephone wall jack and can make calls to any ordinary phone user. When a call is placed to another STU-III unit that is properly set up, one caller can ask the other to initiate secure transmission. They then press a button on their telephones and, after a 15-second delay, their call is encrypted to prevent eavesdropping. There are portable and militarized versions and most STU-IIIs contained an internal modem and RS-232 port for data and fax transmission. Vendors were AT&T, RCA and Motorola.
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 and are all digital. The greater bandwidth allows higher quality voice and can also be utilized for data and fax transmission through a built-in RS-232 port. STE is intended to replace the older STU-III office system and the KY-68 tactical system. STE sets are backwards compatible with STU-III phones, but not with KY-68 sets.
The TSEC/KL-7, also known as Adonis was an off-line non-reciprocal rotor encryption machine. The KL-7 had rotors to encrypt the text, most of which moved in a complex pattern, controlled by notched rings. The non-moving rotor was fourth from the left of the stack. The KL-7 also encrypted the message indicator.
The National Security Agency took over responsibility for all U.S. Government encryption 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.
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 electronic key material for all NSA encryption systems whose keys are loaded using standard fill devices, and directs the distribution of NSA produced key material. Additionally, EKMS performs account registration, privilege management, ordering, distribution, and accounting to direct the management and distribution of physical COMSEC material for the services. The common EKMS components and standards facilitate interoperability and commonality among the armed services and civilian agencies.
The Secure Communications Interoperability Protocol (SCIP) is a US standard for secure voice and data communication, for circuit-switched one-to-one connections, not packet-switched networks. SCIP derived from the US Government Future Narrowband Digital Terminal (FNBDT) project. SCIP supports a number of different modes, including national and multinational modes which employ different cryptography. Many nations and industries develop SCIP devices to support the multinational and national modes of SCIP.
SAVILLE is a classified NSA Type 1 encryption algorithm, developed in the late 1960s, jointly by the Government Communications Headquarters (GCHQ) in the UK and the National Security Agency (NSA) in the US. It is used broadly, often for voice encryption, and implemented in many encryption devices.
Secure voice is a term in cryptography for the encryption of voice communication over a range of communication types such as radio, telephone or IP.
The Automatic Secure Voice Communications Network (AUTOSEVOCOM) was a worldwide, switched, secure voice network for the United States Armed Forces, which was operational from the late 1960s to the end of the 1980s. It was closely related to the Automatic Voice Network or AUTOVON, which was the main non-secure switched telephone network for the military.
A secure telephone is a telephone that provides voice security in the form of end-to-end encryption for the telephone call, and in some cases also the mutual authentication of the call parties, protecting them against a man-in-the-middle attack. Concerns about massive growth of telephone tapping incidents led to growing demand for secure telephones.
Over-the-air rekeying (OTAR) refers to transmitting or updating encryption keys (rekeying) in secure information systems by conveying the keys via encrypted electronic communication channels. It is also referred to as over-the-air transfer (OTAT), or over-the-air distribution (OTAD), depending on the specific type, use, and transmission means of the key being changed. Although the acronym refers specifically to radio transmission, the technology is also employed via wire, cable, or optical fiber.
The KY-3 (TSEC/KY-3) is a secure telephone system developed by the U.S. National Security Agency in the early 1960s. It was one of the first widely accepted voice voice encryption systems. The "TSEC" prefix to the model number indicates NSA's Telecommunications Security nomenclature system.
The Navajo I is a secure telephone built into a briefcase that was developed by the U.S. National Security Agency. According to information on display in 2002 at the NSA's National Cryptologic Museum, 110 units were built in the 1980s for use by senior government officials when traveling. It uses the linear predictive coding algorithm LPC-10 at 2.4 kilobits/second.
The STU-I, like its successors sometimes known as a "stew phone", was a secure telephone developed by the U.S. National Security Agency for use by senior U.S. government officials in the 1970s.
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