Public-key cryptography, James Ellis and Clifford Cocks

Vic
4 min readDec 6, 2021

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People who are familiar with cybersecurity will know what “Public-key cryptography” is, and I say this in quotes because it was one of the biggest inventions in cybersecurity and If you read about it in detail, you will find two names. Whitfield Diffie and Martin Hellman, 2 men at MIT brought out the idea into implementation over the internet with the help of an algorithm that perfectly used public-key cryptography.

Before I talk further, I would like you to know what public cryptography is since this story is about honoring two men and you should know about their work.

The idea of public-key cryptography is to send messages across 2 machines, it could be two users namely Alice and bob or it can be a client and a server without anyone reading these messages with the help of cryptography. Now some of you might be wondering why public-key cryptography, why not other protocols such as DES or triple DES for that matter. Well, the answer is quite simple, they are not scalable and hence not feasible to use in something as broad as the internet with millions of users.

Public-key cryptography is based on making encrypted keys available to the public. How does that protect the message being sent over the internet? It does that because these public keys can only be used to encrypt, but one needs a private key to decrypt which is not available publically. So, for Bob and Alice to communicate securely, they have to know the public keys of each other and they need to have private keys so that they can decrypt these messages. Amazing right? A very simple idea which was founded in the 60s and brought in the world in the 70s.

To better illustrate the mechanism, I will provide a picture. In a nutshell, if bob wants to send a message to Alice, he will use Alice’s public key to encrypt the message, and Alice will use her private key to decrypt and read it.

But this is not what I wanted to talk about in this story, I wanted to highlight the real heroes who brought this concept into the world and were silenced by their government till the 90s.

James Ellis, an employee at GCHQ (A British organization) thought about public-key encryption in the 60s and wrote a paper on public-key cryptography, unfortunately, he didn’t have an algorithm to implement this or enough computational power.

In the coming years, James Ellis met a coworker Clifford Cocks. A mathematician, who had an algorithm to implement the idea of James Ellis and they did implement it! only to have it hidden as a secret since the British government didn’t allow them to talk about it.

It was as if their work never existed!

After a decade Deffie and Hellman invented the same and publicized it into the world, They watched it get famous. Later in the 90s the British government finally decided to tell the world about James Ellis and Clifford Cocks, sadly James Ellis passed away before he could witness it. The true inventors got recognition for their work after 30 years!

It is said that Deffie once heard about James Ellis after a conference and he took a plane to meet James Ellis. When he did meet him, this is what James Ellis said: “You did more with it compared to what we would have done”.

Yes, the credit goes to all four of them but the real inventors behind it are still not recognized much. This piece is to remind the world of the two great men James Ellis and Clifford Cocks.

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Vic

A software engineer, orator, video editor, chef (At least for myself), singer (Not exactly good), artist (Decent one) and a writer (Okayish one).