Editing Public-key cryptography (section)

=== Classified discovery ===
In 1970, [[James H. Ellis]], a British cryptographer at the UK [[Government Communications Headquarters]] (GCHQ), conceived of the possibility of "non-secret encryption", (now called public key cryptography), but could see no way to implement it.<ref>{{cite web| last=Ellis| first=James H.| title=The Possibility of Secure Non-secret Digital Encryption| date=January 1970|url=https://cryptocellar.org/cesg/possnse.pdf| publisher=CryptoCellar| access-date=18 January 2024}}</ref><ref>{{cite news |last=Sawer |first=Patrick |title=The unsung genius who secured Britain's computer defences and paved the way for safe online shopping |journal=The Telegraph |date=11 March 2016 |url=https://www.newindianexpress.com/world/2016/mar/12/the-anonymous-researcher-who-held-the-key-to-cyber-security-910751.html}}</ref> 

In 1973, his colleague [[Clifford Cocks]] implemented what has become known as the [[RSA (cryptosystem)|RSA encryption algorithm]], giving a practical method of "non-secret encryption", and in 1974 another GCHQ mathematician and cryptographer, [[Malcolm J. Williamson]], developed what is now known as [[Diffie–Hellman key exchange]]. 
The scheme was also passed to the US's [[National Security Agency]].<ref name="zdnet"/> Both organisations had a military focus and only limited computing power was available in any case;  the potential of public key cryptography remained unrealised by either organization:
<blockquote>
I judged it most important for military use ... if you can share your key rapidly and electronically, you have a major advantage over your opponent. Only at the end of the evolution from [[Tim Berners-Lee|Berners-Lee]] designing an open internet architecture for [[CERN]], its adaptation and adoption for the [[Arpanet]] ... did public key cryptography realise its full potential.

—[[Ralph Benjamin]]<ref name="zdnet">{{cite web |url=https://www.zdnet.com/article/gchq-pioneers-on-birth-of-public-key-crypto/ |title=GCHQ pioneers on birth of public key crypto |first=Tom |last=Espiner |date=26 October 2010 |website=[[ZDNet]]}}</ref>
</blockquote>
These discoveries were not publicly acknowledged for 27 years, until the research was declassified by the British government in 1997.<ref name=singh>{{cite book |last=Singh |first=Simon |author-link=Simon Singh |title=The Code Book |publisher=Doubleday |year=1999 |pages=[https://archive.org/details/codebookevolutio00sing/page/279 279]–292|title-link=The Code Book }}</ref>