Editing History of cryptography (section)

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{{original research|date=January 2018}}
{{Use dmy dates|date=December 2020}}
Cryptography, the use of codes and ciphers, began thousands of years ago.<ref name="Brief Hist" /> Until recent decades, it has been the story of what might be called [[classical cryptography]] — that is, of methods of [[encryption]] that use pen and paper, or perhaps simple mechanical aids. In the early 20th century, the invention of complex mechanical and electromechanical machines, such as the [[Enigma (machine)|Enigma]] [[rotor machine]], provided more sophisticated and efficient means of encryption; and the subsequent introduction of electronics and computing has allowed elaborate schemes of still greater complexity, most of which are entirely unsuited to pen and paper.

The development of [[cryptography]] has been paralleled by the development of [[cryptanalysis]] —  the "breaking" of codes and [[cipher]]s. The discovery and application, early on, of [[frequency analysis]] to the reading of encrypted communications has, on occasion, altered the course of history.  Thus the [[Zimmermann Telegram]] triggered the United States' entry into World War I; and [[Allies of World War II|Allies]] reading of [[Nazi Germany]]'s ciphers shortened World War II, in some evaluations by as much as two years.

Until the 1960s, secure cryptography was largely the preserve of governments. Two events have since brought it squarely into the public domain: the creation of a public encryption standard ([[Data Encryption Standard|DES]]), and the invention of [[public-key cryptography]].