page_title: NSA encryption systems
section_title: Voice encryption
hierarchical_section_title: NSA encryption systems / NSA encryption by type of application / Voice encryption
context_page_description: 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.
  Rotor machines from the 1940s and 1950s were mechanical marvels. The first generation electronic systems were quirky devices with cantankerous punched card readers for loading keys and failure-prone, tricky-to-maintain vacuum tube circuitry. Late 20th century systems are just black boxes, often literally. In fact they are called blackers in NSA parlance because they convert plaintext classified signals into encrypted unclassified ciphertext signals. They typically have electrical connectors for the red signals, the black signals, electrical power, and a port for loading keys.
context_section_description: True voice encryption (as opposed to less secure scrambler technology) was pioneered during World War II with the 50-ton SIGSALY, 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:
  STU I and STU II - These systems were expensive and cumbersome and were generally limited to the highest levels of command
  STU-III - These telephone sets operated over ordinary telephone lines and featured the use of security tokens and public key cryptography, 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 (STE) - This system is intended to replace STU-III. It uses wide-bandwidth voice transmitted over ISDN 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 - 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  A series of systems for tactical voice encryption including the KY-57 man portable unit and KY-58 for aircraft
  HAVE QUICK and SINCGARS use NSA-supplied sequence generators to provide secure frequency hopping
  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 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.
  Secure Iridium - NSA helped add encryption to the Iridium commercial mobile phones after it rescued the bankrupt Iridium.
  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 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 personnel who were dealing with the hijackings. See Communication during the September 11, 2001 attacks.
caption: KY-68 tactical secure telephone.
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