James Henry Ellis (25 September 1924 – 25 November 1997) was a British engineer and cryptographer. Born in Australia but raised and educated in Britain, Ellis joined GCHQ in 1952. He worked on a number of cryptographic projects, but is credited with some of the original thinking that developed into the field of Public Key Cryptography (PKC).

James Henry Ellis
Born(1924-09-25)25 September 1924
Died25 November 1997(1997-11-25) (aged 73)
Known forNon-secret encryption
Scientific career

Personal life edit

Ellis was born in Australia, but was raised in Britain and orphaned at an early age. He lived with his grandparents in London's East End.[1] Ellis showed an early gift for mathematics and physics while attending grammar school in Leyton. He attended Imperial College London. In 1949, Ellis married Brenda, an artist and designer.[2]

Development of non-secret encryption edit

Ellis first proposed his scheme for "non-secret encryption" in 1970, in a (then) secret GCHQ internal report "The Possibility of Secure Non-Secret Digital Encryption".[3] Ellis said that the idea first occurred to him after reading a paper from World War II by someone at Bell Labs describing the scheme named Project C43,[1] a way to protect voice communications by the receiver adding (and then later subtracting) random noise.[4]

Clifford Cocks and Malcom Williamson, two other GCHQ cryptographers, furthered Ellis' initial PKC related work. As all of this work prior to 1997 was classified, it never became part of very significant mainstream initiatives that developed into modern PKC commercial endeavors, such as the work on Diffie–Hellman key exchange, RSA and other PKC linked initiatives which have become part of the modern world of Internet security.[5]

On 18 December 1997, Clifford Cocks delivered a public talk which contained a brief history of GCHQ's contribution to PKC.[6] In March 2016, Robert Hannigan, the director of GCHQ made a speech at MIT re-emphasising GCHQ's early contribution to public-key cryptography and in particular the contributions of Ellis, Cocks and Williamson.[2][7]

References edit

  1. ^ a b "The Open Secret". Wired. 1 April 1999. Archived from the original on 26 March 2023.
  2. ^ a b Sawer, Patrick (11 March 2016), "The unsung genius who secured Britain's computer defences and paved the way for safe online shopping", The Daily Telegraph, archived from the original on 11 March 2016
  3. ^ "GCHQ CESG Research Report No. 3006" (PDF). Archived from the original (PDF) on 16 February 2017. Retrieved 15 February 2017.
  4. ^ "Final Report on Project C-43, Part 1 – Speech Privacy Systems" (PDF). October 1944: 23, 24. Archived (PDF) from the original on 20 June 2013. {{cite journal}}: Cite journal requires |journal= (help)
  5. ^ "GCHQ trio recognised for key to secure shopping online". BBC News. 5 October 2010. Retrieved 17 November 2023.
  6. ^ "The Alternative History of Public-Key Cryptography". cryptome.org. Retrieved 17 November 2023.
  7. ^ Director Robert Hannigan dispels some myths about encryption in MIT speech, GCHQ, 7 March 2016, retrieved 14 March 2016

External links edit