Milestone-Proposal:Invention of Public-key Cryptography

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Docket #:2008-15</div> This is a draft proposal, that has not yet been submitted. To submit this proposal, click on "Edit with form", check the "Submit this proposal for review" box at the bottom, and save the page.

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

Is the achievement you are proposing within IEEE’s fields of interest? (e.g. “the theory and practice of electrical, electronics, communications and computer engineering, as well as computer science, the allied branches of engineering and the related arts and sciences” – from the IEEE Constitution)

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 an IEEE Organizational Unit 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 Electrical Engineering 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:

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: Senior officer name masked to public

IEEE Organizational Unit(s) arranging the dedication ceremony:

Unit: UKRI Section
Senior Officer Name: Senior officer name masked to public

Unit: UKRI Section
Senior Officer Name: Senior officer name masked to public

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

IEEE Section: UKRI Section
IEEE Section Chair name: Section chair name masked to public

Milestone proposer(s):

Proposer name: Proposer's name masked to public
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 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)?

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.

References 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 citations to pages in scholarly books. 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.

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" .