Editing NSA encryption systems (section)

{{Short description|Aspect of US National Security Agency}}
{{More citations needed|date=March 2007}}

The [[National Security Agency]] took over responsibility for all [[US government]] [[encryption]] systems when it was formed in 1952. The technical details of most NSA-approved systems are still [[Classified information in the United States|classified]], but much more about its early systems have become known and its most modern systems share at least some features with commercial products.

NSA and its predecessors have produced a number of [[cipher device]]s. [[Rotor machine]]s from the 1940s and 1950s were mechanical marvels. The first generation electronic systems were quirky devices with cantankerous [[punched card]] readers for loading [[key (cryptography)|keys]] and failure-prone, tricky-to-maintain [[vacuum tube]] circuitry. Late 20th century systems are just [[Black box (systems)|black box]]es, often literally. In fact they are called ''[[blacker (security)|blacker]]s'' in NSA parlance because they convert [[plaintext]] classified signals (''red'') into encrypted unclassified [[ciphertext]] signals (''black''). They typically have [[electrical connector]]s for the red signals, the black signals, electrical power, and a port for loading keys. Controls can be limited to selecting between [[fill device|key fill]], normal operation, and diagnostic modes and an all important ''[[Zeroisation|zeroize]]'' button that erases [[classified information]] 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]] or [[AN/PRC-152]], can interoperate with most current NSA [[cryptosystem]]s.

Little is publicly known about the algorithms NSA has developed for protecting [[Classified information in the United States|classified information]], called [[Type 1 encryption|Type 1]] algorithms by the agency. In 2003, for the first time in its history, NSA-approved two published algorithms, [[Skipjack (cipher)|Skipjack]] and [[Advanced Encryption Standard|AES]], for [[Type 1 encryption|Type 1]] use in NSA-approved systems.