page_title: NSA encryption systems
section_title: Third generation: integrated circuits
hierarchical_section_title: NSA encryption systems / Five generations of NSA encryption / Third generation: integrated circuits
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: Third generation systems (1980s) were transistorized and based on integrated circuits 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 that could be pulled through a hand held reader (KOI-18) connected to the fill port. Other, portable electronic fill devices (KYK-13, etc.) were available as well.
caption: KOI-18 field paper tape reader.
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