- Eli Ben-Sasson, co-founder of StarkWare and a key figure behind zk-STARKs and Zcash, says zero-knowledge proofs are becoming essential infrastructure for blockchain privacy, scalability, and trust.
- In the interview, he explains why ZK technology could help protect Bitcoin from future quantum threats while also making financial compliance more private and efficient.
What originally convinced you that ZK proofs would become foundational to blockchain?
Eli Ben-Sasson: Most of all, it was the warm reaction of core developers of Bitcoin back in 2013, most notably Greg Maxwell and Mike Hearn, who convinced me that they urgently needed the code I was building for privacy and for scale. That convinced me more than anything else.
I was giving talks about my research at academic conferences, and I was even trying to found a startup around it, but there was no reception like the one I received from those Bitcoin developers. That very sincere reaction is what convinced me.
What is the biggest misconception about ZK that still persists today?
Eli Ben-Sasson: The biggest misconception is that ZK is very hard to access and use, both for developers and for users.
People think it is really, really complicated. That part is true. But they also think that because it is complicated, it is still inaccessible to developers, users, and entrepreneurs. That is the misconception.
Today, it is very usable with programming languages like Cairo and blockchains like Starknet. You can basically vibe-code an application that uses it.
How did those early conversations with Vitalik shape the direction of modern blockchain innovation?
Eli Ben-Sasson: Vitalik is one of the most important voices in blockchain, maybe even the most influential one. He certainly was for several years. The fact that he was very supportive of ZK helped tremendously.
I’ll give a few examples. He wrote some of the first popular explanations of how the STARK protocol and the FRI protocol, which I co-invented, work. He was also the one who basically priced StarkWare’s seed round. I believe it was his first investment ever, and of course that gave a lot of support to StarkWare.
Finally, the first paid project StarkWare worked on was one commissioned by the Ethereum Foundation. All of this came from Vitalik’s support for ZK, StarkWare, and zk-STARKs.
You mentioned founding your company during a walk through a fish market. What does that story reveal about how early the vision for ZK actually was?
Eli Ben-Sasson: It was certainly very, very early.
I’m not sure the fish market itself is the important part. The fish market was a coincidence. Vitalik and I were both attending a conference somewhere in China, and we happened to be walking together when we chanced upon a fish market, which I always find interesting. I love watching people work in different places, and markets are a great place to see people work.
But I must say that investors and VCs in the blockchain world were very visionary about ZK. We had a lot of interest in our seed round. Zcash got a lot of support from people like Naval Ravikant and others.
The more conventional world didn’t see the potential of ZK, but blockchain definitely did. Blockchain teams and innovators saw it.
Your team is now addressing quantum threats to Bitcoin. How real is the “harvest now, decrypt later” risk in practical terms?
Eli Ben-Sasson: For blockchains, it is extremely prevalent.
Anything that is encrypted with cryptography that can be broken by a quantum computer will be broken by a quantum computer. That is for sure. And blockchains keep public records of everything, essentially for eternity.
So yes, it is definitely a big threat. But the bigger threat is that once a quantum computer arrives, chains that have not adopted changes and protected themselves against the quantum threat will have their coins stolen, and the value of the whole system will probably go down significantly.
That is the bigger threat.
What would a quantum-resistant Bitcoin actually look like, and how far are we from getting there?
Eli Ben-Sasson: The good news is that a quantum-resistant Bitcoin would feel, to end users and to the whole world, very much like Bitcoin feels today.
You already use pretty sophisticated hardware and software to generate signatures and track your coins. So on those hardware and software devices, you would be replacing some software.
It is a little bit like the Y2K bug. No one, aside from the people working to protect the world from the Y2K bug, really noticed anything. I’m old enough to remember that.
With Bitcoin, you would probably be asked to press a button, or perform one operation, to make your Bitcoin safe. But it would be very user-friendly.
On the more technical side, the kinds of transactions are going to change. It is hard to see how that happens without allowing transactions that are a little bit more complicated, because quantum-safe signatures are just a bit longer and a bit more computationally intensive.
That said, this is nothing too hard for any computer. Your smartphone can easily generate and process such signatures or transactions. It is really just about changing Bitcoin a little bit.
The biggest problem is governance and community support. The technological work is relatively straightforward. The biggest blocker is whether there is enough support from the Bitcoin community even to work on such things, let alone implement and roll them out.
That is the biggest issue. Technologically, it would be very simple.
You were a key figure behind Zcash. Why do you believe privacy is not optional, but essential for Bitcoin’s long-term survival?
Eli Ben-Sasson: Yes, I was indeed a co-inventor of the technology itself, for the use of ZK, and of the white paper that basically designed the Zcash protocol. I was also a co-founder of the project itself, and I have supported it publicly over the years.
Privacy is essential.
If Bitcoin is to be the rails for the global economy, then privacy cannot be optional, just as privacy is not optional in the current global economy. We don’t allow everyone to see how much money we have, the salaries we pay or receive, or our investments. That is not optional.
It is the same here. Today, Bitcoin is not yet the rails for the full global economy, but I believe it can become that, or crypto at large can become that. And when you reach that point, privacy cannot be optional.
Talk to any CFO of any company and ask them whether they would be comfortable if all their payments to suppliers and employees were made publicly available. You will immediately see why privacy is not optional.
Regulators are increasingly skeptical of privacy. How do you reconcile zero-knowledge systems with compliance requirements?
Eli Ben-Sasson: The amazing thing about zero knowledge is that it can allow you to do even better on things like the Bank Secrecy Act, sanctions, and other regulatory frameworks, because it can make individuals the center of power and place responsibility on them.
Let me explain.
Today, we ask financial institutions to do surveillance on behalf of the state and prove that funds have not gone to or from sanctioned entities. But financial institutions don’t really want to do this. It is not their core business, they are not doing a good job at it, and customers suffer because of that.
It would be much better to move to a system that is a little bit like the way the US treats taxation. Individuals are required to submit their tax forms every year. They are trusted with those tax forms, but of course, once in a while, they can be audited.
ZK can allow individuals to submit zero-knowledge proofs showing that they have not transacted with any address or entity on a sanctions list. If they cannot do that, then they may need to reveal a little bit of information to explain why. Maybe it was a mistake. Maybe their accounts were hacked.
So you can have better privacy and better empowerment of individuals, with actually better compliance. That is what ZK allows you to do.
Looking ahead, do you see zero knowledge becoming more important for scalability, privacy, or entirely new use cases we are not yet thinking about?
Eli Ben-Sasson: The answer is yes to all three.
We already see ZK helping with scalability on things like Starknet. Privacy already exists in Zcash, and now also on Starknet, and we see a lot of use cases for that.
But the most impressive thing you can get is what I like to call ZK threads, which are about empowering individuals to run full blockchains by themselves from their basements and prove that they acted with integrity.
So there is an even bigger class of use cases that we will soon see.
If you had to explain the importance of zero knowledge to a traditional finance executive in one sentence, what would you say?
Eli Ben-Sasson: I would say this: ZK is a new way to deliver trust.
Today, enormous amounts of human effort go into checking records, reconciling accounts, and confirming that businesses and transactions have been handled with integrity. Accountants, executives, auditors, compliance teams — all of them are part of a system designed to answer one basic question: can we trust that this was done correctly?
ZK does not remove the need for judgment, responsibility, or good governance. But it can move a large part of that trust burden from manual checking to mathematics. It lets one party prove to another that something was done correctly, without exposing all the underlying information.
For a financial executive, that is the key point. ZK is not just about efficiency. It is about making trust cheaper, faster, more private, and more reliable.
Thank you for taking the time to answer our questions! You can find more information about Ben-Sasson’s newest book here (click!).
