Milestone-Proposal:Invention of Public-key Cryptography

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Docket #:2008-15

This is a draft proposal, that has not yet been submitted. To submit this proposal, click on the edit button in toolbar above, indicated by an icon displaying a pencil on paper. At the bottom of the form, check the box that says "Submit this proposal to the IEEE History Committee for review. Only check this when the proposal is finished" and save the page.

To the proposer’s knowledge, is this achievement subject to litigation?

Is the achievement you are proposing more than 25 years old?

Is the achievement you are proposing within IEEE’s designated fields as defined by IEEE Bylaw I-104.11, namely: Engineering, Computer Sciences and Information Technology, Physical Sciences, Biological and Medical Sciences, Mathematics, Technical Communications, Education, Management, and Law and Policy.

Did the achievement provide a meaningful benefit for humanity?

Was it of at least regional importance?

Has an IEEE Organizational Unit agreed to pay for the milestone plaque(s)?

Has the IEEE Section(s) in which the plaque(s) will be located agreed to arrange the dedication ceremony?

Has the IEEE Section in which the milestone is located agreed to take responsibility for the plaque after it is dedicated?

Has the owner of the site agreed to have it designated as an IEEE Milestone? Yes

Year or range of years in which the achievement occurred:

1969 (concept invented by James Ellis), 1974 (solution found by Clifford Cocks), 1975 (further solution found by Malcolm Williamson)

Title of the proposed milestone:

Invention of Public-key Cryptography

Plaque citation summarizing the achievement and its significance:

200-250 word abstract describing the significance of the technical achievement being proposed, the person(s) involved, historical context, humanitarian and social impact, as well as any possible controversies the advocate might need to review.

IEEE technical societies and technical councils within whose fields of interest the Milestone proposal resides.

In what IEEE section(s) does it reside?

UKRI Section

IEEE Organizational Unit(s) which have agreed to sponsor the Milestone:

IEEE Organizational Unit(s) paying for milestone plaque(s):

Unit: {{{Unit}}}
Senior Officer Name: Brian Harrington

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: UKRI Section
Senior Officer Name: Dr. Sean McLoone

Unit: UKRI Section
Senior Officer Name: David Teague

IEEE section(s) monitoring the plaque(s):

IEEE Section: UKRI Section
IEEE Section Chair name: Dr Sean McLoone

Milestone proposer(s):

Proposer name: Peter C J Hill
Proposer email: Proposer's email masked to public

Please note: your email address and contact information will be masked on the website for privacy reasons. Only IEEE History Center Staff will be able to view the email address.

Street address(es) and GPS coordinates in decimal form of the intended milestone plaque site(s):

Government Communications Headquarters (GCHQ), Cheltenham, Gloucestershire, GL51 0EX, England

Describe briefly the intended site(s) of the milestone plaque(s). The intended site(s) must have a direct connection with the achievement (e.g. where developed, invented, tested, demonstrated, installed, or operated, etc.). A museum where a device or example of the technology is displayed, or the university where the inventor studied, are not, in themselves, sufficient connection for a milestone plaque.

Please give the address(es) of the plaque site(s) (GPS coordinates if you have them). Also please give the details of the mounting, i.e. on the outside of the building, in the ground floor entrance hall, on a plinth on the grounds, etc. If visitors to the plaque site will need to go through security, or make an appointment, please give the contact information visitors will need. Goverment Communications Headquarters (GCHQ), Cheltenham, England

Are the original buildings extant?


Details of the plaque mounting:

How is the site protected/secured, and in what ways is it accessible to the public?

The site is a secure communications station, but the main entrance area leading to the main building from the outside is public

Who is the present owner of the site(s)?

British Government

What is the historical significance of the work (its technological, scientific, or social importance)? If personal names are included in citation, include justification here. (see section 6 of Milestone Guidelines)

Public-key Cryptography was an outstanding breakthrough. The work of Ellis, Cocks and Williamson was hidden by official secrecy and not revealed until many years later (December 1997). By then, the public recognition had been allocated to the later ‘re-discoveries’ by Diffie, Hellman and Merkle (public key exchange) at Stanford and Rivest, Shamir and Adleman (RSA algorithm) at MIT. The commercial success of products based on these concepts is now well known, and internet e-commerce could hardly have developed without their availability. This was also a major mathematical breakthrough in cryptography, since it represents a solution to a problem previously considered insoluble (e.g. how to communicate securely without having to exchange keys) It has a sociological significance, in showing the contrast between secret classified research and open academic research (and the general need for the latter to stimulate commercial applications) Ellis died (aged 73) just before public credit for his work could be given.

What obstacles (technical, political, geographic) needed to be overcome?

Technical – to solve the problem of key distribution without using a

symmetric key system, in which both encrypt and decrypt keys have to be sent
through secure channels, and to develop a suitable asymmetric mathematical
encryption/decryption algorithm.
Political – the research work on public-key cryptography was classified secret.
Geographic – there were no obstacles as such.

What features set this work apart from similar achievements?

The work was carried out in complete secrecy and could not be revealed until it was decided that no further benefit to national security could be achieved by not revealing it. Like the cryptanalysis done during World War 2 at Bletchley Park (now an IEEE Historical Milestone site, since March 2003), the significance of the work was available for public assessment only long after the work was actually carried out.

Supporting texts and citations to establish the dates, location, and importance of the achievement: Minimum of five (5), but as many as needed to support the milestone, such as patents, contemporary newspaper articles, journal articles, or chapters in scholarly books. 'Scholarly' is defined as peer-reviewed, with references, and published. You must supply the texts or excerpts themselves, not just the references. At least one of the references must be from a scholarly book or journal article. All supporting materials must be in English, or accompanied by an English translation.

Supporting materials (supported formats: GIF, JPEG, PNG, PDF, DOC): All supporting materials must be in English, or if not in English, accompanied by an English translation. You must supply the texts or excerpts themselves, not just the references. For documents that are copyright-encumbered, or which you do not have rights to post, email the documents themselves to Please see the Milestone Program Guidelines for more information.

Please email a jpeg or PDF a letter in English, or with English translation, from the site owner(s) giving permission to place IEEE milestone plaque on the property, and a letter (or forwarded email) from the appropriate Section Chair supporting the Milestone application to with the subject line "Attention: Milestone Administrator." Note that there are multiple texts of the letter depending on whether an IEEE organizational unit other than the section will be paying for the plaque(s).

Please recommend reviewers by emailing their names and email addresses to Please include the docket number and brief title of your proposal in the subject line of all emails.