James Henry Ellis (25 September 1924 – 25 November 1997) was a British engineer and

cryptographer Cryptography, or cryptology (from "hidden, secret"; and ''graphein'', "to write", or '' -logia'', "study", respectively), is the practice and study of techniques for secure communication in the presence of adversarial behavior. More gen ...

. Born in Australia but raised and educated in Britain, Ellis joined

GCHQ Government Communications Headquarters (GCHQ) is an intelligence and security organisation responsible for providing signals intelligence (SIGINT) and information assurance (IA) to the government and armed forces of the United Kingdom. Primar ...

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 Public-key cryptography, or asymmetric cryptography, is the field of cryptographic systems that use pairs of related keys. Each key pair consists of a public key and a corresponding private key. Key pairs are generated with cryptographic al ...

(PKC).

Personal life

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. Ellis showed an early gift for mathematics and physics while attending

grammar school A grammar school is one of several different types of school in the history of education in the United Kingdom and other English-speaking countries, originally a Latin school, school teaching Latin, but more recently an academically oriented Se ...

Leyton Leyton ( ) is a town in East London, England, within the London Borough of Waltham Forest. It borders Walthamstow to the north, Leytonstone to the east, and Stratford to the south, with Clapton, Hackney Wick and Homerton, across the Ri ...

. He attended

Imperial College London Imperial College London, also known as Imperial, is a Public university, public research university in London, England. Its history began with Prince Albert of Saxe-Coburg and Gotha, Prince Albert, husband of Queen Victoria, who envisioned a Al ...

. In 1949, Ellis married Brenda, an artist and designer.

Development of non-secret encryption

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". Ellis said that the idea first occurred to him after reading a paper from

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

by someone at

Bell Labs Nokia Bell Labs, commonly referred to as ''Bell Labs'', is an American industrial research and development company owned by Finnish technology company Nokia. With headquarters located in Murray Hill, New Jersey, Murray Hill, New Jersey, the compa ...

describing the scheme named Project C43, a way to protect voice communications by the receiver adding (and then later subtracting) random noise.

Clifford Cocks Clifford Christopher Cocks (born 28 December 1950) is a British mathematician and cryptographer. In the early 1970s, while working at the United Kingdom Government Communications Headquarters (GCHQ), he developed an early public-key cryptogra ...

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 Diffie–Hellman (DH) key exchangeSynonyms of Diffie–Hellman key exchange include: * Diffie–Hellman–Merkle key exchange * Diffie–Hellman key agreement * Diffie–Hellman key establishment * Diffie–Hellman key negotiation * Exponential ke ...

, RSA and other PKC linked initiatives which have become part of the modern world of

Internet security Internet security is a branch of computer security. It encompasses the Internet, browser security, web site security, and network security as it applies to other applications or operating systems as a whole. Its objective is to establish rules ...

. On 18 December 1997, Clifford Cocks delivered a public talk which contained a brief history of GCHQ's contribution to PKC. In March 2016, Robert Hannigan, the director of GCHQ made a speech at

MIT The Massachusetts Institute of Technology (MIT) is a private research university in Cambridge, Massachusetts, United States. Established in 1861, MIT has played a significant role in the development of many areas of modern technology and sc ...

re-emphasising GCHQ's early contribution to public-key cryptography and in particular the contributions of Ellis, Cocks and Williamson.Director Robert Hannigan dispels some myths about encryption in MIT speech
GCHQ, 7 March 2016, retrieved 14 March 2016

References

External links

* * Ellis, J.H.
The possibility of secure non-secret digital encryption
CSEG Report 3006, January 1970. * Ellis, J.H.
The possibility of secure non-secret analogue encryption
CSEG Report 3007, May 1970. {{DEFAULTSORT:Ellis, James H. Alumni of Imperial College London GCHQ cryptographers History of computing in the United Kingdom People from Leytonstone Public-key cryptographers 1924 births 1997 deaths Engineers from London