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Picture the British secretly rewriting crypto history

Diving into the 1970s breakthrough of public key cryptography

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Quick life update: I just moved to NYC 🗽 If you live here, I would love to meet IRL :) Just reply to this email if you want to grab some coffee or food.

Lately, I've been having a blast diving into the history of cryptography. Not just the early days of the crypto market we know today, but rather all the events leading up to the launch of the bitcoin whitepaper.

Yesterday, I wrote a post covering the OG cypherpunk SF meetups and the e-mail list where many of the most important conversations in this field took place. The list consisted of folks such as Nick Szabo, Phil Zimmerman, Hal Finney, etc. Here's the key takeaway:

These early privacy advocates had the foresight that the development of the internet was a double edged sword. As great as it was at enhancing digital communication, the internet could quickly be controlled & monitored by the government if no action was taken.

You can read the full post here!

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Today at a Glance

In today's post, I want to cover the breakthrough of arguably the most crucial component to making the internet a secure place: public key cryptography (PKC).

Public key cryptography, also known as asymmetric cryptography, is the backbone of most internet security we take granted for today. TLS, PGP, SSH, and of course bitcoin are just a few examples of where asymmetric cryptography is used. Don't sweat if you don't know what those acronyms mean, I'll cover them in a future post 🤝

The internet would have only a fraction of its current functionality if not for the breakthrough of public key cryptography.

Heck, you wouldn't even be able to send an e-mail securely.

The story of PKC is quite interesting. It involves 3 researchers from Stanford and the NSA. But the twist is that it was 20 years later when these folks found out they weren't even the first people to have this brilliant breakthrough 👀

Sections Below:

  1. The shortcomings of symmetric cryptography

  2. A professor, researcher, & student change the world

  3. The Brits surprise the computing world

Let's dive in 🚀

The shortcomings of symmetric cryptography

Up until the 1970s, the only form of cryptography that had been used for centuries was symmetric cryptography. Basically, in symmetric cryptography, the key used to encrypt and decrypt messages are the same. Let's first breakdown what this means.

Consider a simple example. Let's say I want to send the message "subscribe to the bigger picture" to you. Previously, you and I had both met up and discussed the key that we would use to code and decode the message. In this case, the cipher is to shift every letter two letters back in the alphabet. So "d" would become "b", "o" would become "m", and so on. Note: this kind of cipher where you move the letters by x spots is known as a Caesar Cipher.

Plaintext: subscribe to the bigger picture

Ciphertext: qayagpgr vk rfc aehhgt ncrsgf

The key part to note here is that I would somehow have to communicate with you (the receiver) what the key itself is. If not, there's no difference in knowledge between you and a codebreaker.

As important as symmetric cryptography is, it still comes with a crutch. What if there's no way for you to communicate the key to the intended receiver safely? What if a bad actor intercepts the key? What if there's no reliable, secure channel to convey the key? The whole purpose is defeated.

That's where asymmetric cryptography comes in.

A professor, researcher, & student change the world

In the mid 1970s at Stanford, there were three brilliant minds working in parallel to make asymmetric cryptography a reality. Two of them, Whitfield Diffie (researcher) and Martin Hellman (professor) were working together. And the third was Ralph Merkle, a student in the electrical engineering department who came up with the concept of Merkle Trees.

Diffie & Hellman

The idea of asymmetric functionality had been around for a while. A concept known as a trapdoor function was central to this idea. A trapdoor function is easy to compute in one direction, yet hard to compute in the opposite direction without special information. This is where the factorization problem in mathematics comes in - it's easy to check if the factored down numbers are correct, but difficult to actually come up with them in the first place.


So how does asymmetric cryptography work?

Picture your mailbox. You have the keys to it and only you can access it. However, anyone is able to drop a letter or package into your mailbox.

So, if I want to send you a confidential message, I would use your public key (the mailbox) to 'lock' (encrypt) the message. Once the message is encrypted with your public key, only your private key can unlock (decrypt) and read the message. Most importantly, you never have to share your private key with anyone, not even with the person sending you the message.

Mailbox : Mailbox Key :: Public Key : Private Key

Now, if a bad actor intercepts the encrypted message, it would be of no use to them because they do not have the private key necessary to decrypt it. And since the private key is never transmitted or shared, it remains secure.

Of course, I've simplified this down as a standard example used in textbooks. But the actual complexity of coming to this solution is 🤯.

On November 6th, 1976, Diffie and Hellman publish their seminal paper, New Directions in Cryptography. This marked the beginning of asymmetric cryptography.

Link to paper

Note: Merkle did not initially receive much credit for helping discover PKC. His work was cited in the original research paper published by Diffie & Hellman. However, by the late '90s, Hellman tried to ensure he was given as much credit for the breakthrough as PKC would not have been possible without him.

Here's an interview of Diffie explaining the night he had the breakthrough!

After the paper was published, most computer scientists were shocked and skeptical. No one had even imagined this was possible. Eventually, as people understood the logic, it gained more steam. In fact, in the video above Diffie said it took an hour just to explain Hellman the initial idea itself.

One of the earliest institutions to catch on to what just happened was the NSA. And they were absolutely frightened.

After the publication of “New Directions in Cryptography” and another paper on the DES key size, the conflict intensified as the NSA waged a concerted campaign to limit the distribution of Diffie and Hellman’s research.

An NSA employee even sent a letter to the publishers warning that the authors could be subject to prison time for violating U.S. laws restricting export of military weapons. -Stanford News

It wasn't until the NSA and the US government realized that public key cryptography was going to unlock billions of dollars of economic value through e-commerce did they really back off.

Today, we can thank this paper for completely revolutionizing the way we communicate and interact digitally - without it, you would not have been able to read this newsletter securely on your computer.

The Brits surprise the computing world

Almost 20 years after the discovery of public key cryptography, the British intelligence agency, GCHQ, announced that it had actually made the breakthrough before Diffie & Hellman's paper.

GCHQ revealed that its researchers, James Ellis, Clifford Cocks, and Malcolm Williamson, had developed key concepts of public key cryptography in the early 1970s, predating the work of Diffie, Hellman, and Merkle. The British trio had essentially arrived at the concept of asymmetric cryptography independently and, notably, prior to their American counterparts. However, due to the secretive nature of intelligence work, their discovery was classified and kept under wraps.

But at the end of the day, it was the work by Diffie, Hellman, and Merkle that completely changed the world. If not for their brilliance and courage, the world would most likely look very different today.

This revelation also makes me wonder what the heck else is out there? Are there inventions already made that the governments are hiding from us today? Clearly they have the minds for it.

That's all for today's post - if you enjoyed, I'd love for you to share with your friends in crypto :)

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