James H. Ellis
| James Henry Ellis | |
|---|---|
| Born |
25 September 1924 Australia |
| Died | 25 November 1997 (aged 73) |
| Nationality | British |
| Fields | Cryptography |
| Institutions | |
| Alma mater | Imperial College London |
| Known for | Non-secret encryption |
James Henry Ellis (25 September 1924 – 25 November 1997) was a British engineer and cryptographer. In 1970, while working at the Government Communications Headquarters (GCHQ) in Cheltenham he conceived of the possibility of "non-secret encryption", more commonly termed public-key cryptography.
Ellis was born in Australia, although he was conceived in Britain, and grew up there. He almost died at birth, and it was thought that he might be mentally retarded. Instead he soon showed a gift for mathematics and physics at a grammar school in Leyton, and gained a degree in physics. He then worked at the Post Office Research Station at Dollis Hill. In 1952, Ellis joined GCHQ in Eastcote, west London. In 1965, he moved to Cheltenham to join the newly formed Communications-Electronics Security Group (CESG), an arm of GCHQ. In 1949, Ellis married Brenda, an artist and designer, and they had three children but she never knew anything about his work.
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 by someone at Bell Labs describing a way to protect voice communications by the receiver adding (and then later subtracting) random noise (possibly this 1944 paper or the 1945 paper co-authored by Claude Shannon). He realised that 'noise' could be applied mathematically but was unable to devise a way to implement the idea.
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