The Story Behind RSA: The Invention That Secured the Internet (ft. Turing Award Winner Ron Rivest)

**Ron Rivest** (0:00)
People started to realize that standards were essential, that cryptography was about communication. Communication required standards. RSA was the natural candidate for standards, but RSA had the defect, in some eyes, that it could also be used for encryption. The idea that was proposed was the DSA standard, which could only be used for signatures. But to me, signatures were probably more interest. One of the big contributions of the Diffie-Hellman paper was the idea that you can sign things, you can authenticate messages as well.

**Dan Boneh** (0:28)
Suppose we wait a thousand years, are we going to have a quantum computer that can break RSA? Or do you think it's just not possible, period?

**Ron Rivest** (0:33)
People think that quantum computing is going to replace your laptop and do everything faster and so on too, and it's not. There's the question whether P equals NP. Within a hundred years, we should know the answer to that question, I would hope. I think cryptographers' nightmare is waking up some morning and finding out that...

**Tim Roughgarden** (0:56)
Hi, everyone, and welcome to First Principles, a series by the team at A16z Crypto. I'm Tim Roughgarden. I'm the Head of Research at A16z Crypto. Today, we're exploring the mechanics of establishing trust between strangers on the Internet. Public-key cryptography is what makes this possible, using math to let strangers communicate securely and verify messages without ever sharing a secret in advance. Our guest today is Ron Rivest, a Turing Award-winning cryptographer and Institute professor at MIT, probably best known as the R in RSA, the public-key cryptosystem he co-invented that underpins secure communication across the Internet. Decades later, the core idea still forms the foundation for everything from Internet security to blockchains. Joining us is Dan Boneh, Professor of Computer Science at Stanford, also Senior Research Advisor at A16z Crypto, whose pioneering work on pairing-based cryptography earned him the Girdle Prize and the ACM Prize in Computing, and opened up entirely new categories of cryptographic primitives. Together, we talk with Dr. Rivest about the invention of RSA, about the evolution of cryptography, and about how these ideas continue to shape the future, touching on everything from cryptographic hash functions to post-quantum security. Here's our conversation. So Dan, it's very exciting. We're about to talk to Ron Rivest.
In blockchain protocols, cryptography is used in many ways, but in my mind, there's two cryptographic primitives without which it doesn't even make sense to talk about blockchain protocols. You just literally couldn't do them. One of them being digital signatures, the other being cryptographic hash functions.
Ron Rivest has been a very key figure in the development of both of those primitives. So I was hoping you could just talk a little bit about what role do those primitives play in modern blockchain protocols, and then a little bit about Ron's role in their evolution.

**Dan Boneh** (2:53)
Absolutely.
It's so cool that we get to interview Ron Rivest. He's one of the gods of cryptography. So Tim, like you said, digital signatures and cryptographic hash functions, they're kind of core to blockchains. Digital signatures, of course, are used for signing transactions. When I want to pay you, I have to sign a transaction. That's done using a digital signature. They also play an important role in consensus. Once enough validators sign on the block, the block is finalized. So many consensus protocols use digital signatures. They're also used quite heavily in decision-making, governance, and DAOs and such. All those depend on digital signatures.
And guess what? The first digital signature that was ever created is actually the RSA digital signature scheme, invented by Rivest, Shamir, and Adleman, RSA. And we're going to be speaking with Ron Rivest, who is actually the R in RSA.
Of course, there are many other signature schemes that have been invented since, most famously maybe in the blockchain space. ECBSA is a signature scheme that's used widely, that uses a slightly different technology than what RSA is using. And then Schnorr is another signature scheme that uses, this more maybe more similar to ECBSA. And I guess we also have the BLS family of digital signatures. So those kind of all together, all of those play a pretty critical role in the world of blockchains.

**Tim Roughgarden** (4:12)
And because he's too modest to say it, let me just say my co-host is the B in BLS signatures.

**Dan Boneh** (4:17)
Well, thank you, Tim. But again, you have to remember the original signature scheme, digital signature scheme is actually RSA. Maybe it's worthwhile saying that kind of RSA, there's some moving parts to the scheme itself. But fundamentally, the security is based on the fact that if I give you an integer number, factoring that integer number into its prime factors is difficult. Again, the RSA signature scheme depends on a slightly more intricate complexity assumption. But by and large, you can think that security is derived from the fact that factoring is difficult. And I'm sure we'll get into that with Ron Rivest when we discuss with him.