As quantum computing researchers celebrate breakthrough after breakthrough, Web3’s $4 trillion asset base faces a ticking time bomb. Last December, Google announced that its quantum Willow chip performed a calculation in less than five minutes that would have taken an advanced supercomputer ten septillion years (about 100 trillion times longer than our universe is old). Drug discovery, materials science, economic modeling and optimization problems of all kinds will enter a golden age thanks to quantum. But most modern encryption, which relies on mathematical puzzles that are functionally impossible for a classical computer to solve, could be broken instantly by quantum.
In Web3, adversaries collect already encrypted blockchain data to crack later when quantum comes of age. An investment in crypto is essentially an investment in the integrity of cryptography, which quantum computing directly threatens.
Fortunately, researchers have demonstrated that specialized zero-knowledge (ZK) cryptography can help quantum-secure the industry’s most valuable blockchains, ensuring that Web3 can reap the benefits of quantum – from new antibiotics to hyper-optimized supply chains – while insulating it from the dangers.
The quantum advantage
On October 22, Google published verifiable results in Nature showing that its quantum chip is “useful for learning the structure of systems in nature, from molecules to magnets to black holes, [running] 13,000 times faster than the best classical algorithm on one of the world’s fastest supercomputers.” What is amazing about these results is that they were not based on a constructed benchmark, like the previous example, but on applied problems with direct scientific merit.
Despite quantum’s apparent bounty to human knowledge, it poses an undeniable threat to cryptography in general and the nearly $4 trillion digital asset base in particular. The Human Rights Foundation released a report showing that over six million BTC are in early, “quantum vulnerable” account types, including Satoshi’s dormant 1.1 million BTC. These will likely be the first “Q Day” (the day quantum becomes powerful enough to break public key encryption) victims.
Both Ethereum and Bitcoin rely on the Elliptic Curve Digital Signature Algorithm (ECDSA), which is famously vulnerable to “Shor’s algorithm”, a quantum algorithm designed in the 1990s to quickly compute the prime factors of large integers, a problem otherwise completely intractable to classical computers. It is even theoretically possible that quantum has already broken Bitcoin; we just haven’t realized it yet.
And yet many researchers have dismissed the threat. Jameson Lopp of cypherpunk fame wrote on X that “the fear and uncertainty surrounding quantum computing may well be a greater threat than quantum computing itself.” In other words, the only thing we have to fear is fear itself. But no matter who you ask, the quantum threat is non-zero. Vitalik Buterin puts the chance of quantum breaking Ethereum at 20% by 2030. And that means we need to be prepared.
The timeline matters a lot – a lot. Harvest now, decrypt later, moves the timeline up much earlier. Potential attackers (including nation-states and hacker groups) store encrypted blockchain data—from wallet backups to custody data exchanges—to crack when quantum comes of age. Every transaction broadcast to the network, every public key exposed, becomes ammunition for future attacks. The window for implementing quantum-resistant cryptography narrows with each passing quarter.
Enter zero knowledge
The beauty of Zero-knowledge (ZK) cryptography lies in its elegance and simplicity. A prover can convince a verifier that something is true without revealing any information beyond the validity itself. As ZK technology has matured, sample times have decreased from hours to seconds, while sample sizes have shrunk from megabytes to kilobytes. In particular, the computational cost of artificial intelligence remains high, limiting its applicability to high-stakes environments such as Web3, traditional banking, and defense.
Zero knowledge and quantum
At first glance, it may not be obvious how zero-knowledge technology can protect blockchains from quantum attacks. Zero-knowledge proofs are privacy tools, a way to prove something is true without revealing any underlying information. But the same privacy-preserving techniques can also be built on top of quantum-resistant mathematics, making ZK a broad shield for blockchains. Hash-based proofs (using zk-STARKs) and lattice-based proofs, built on problems that even powerful quantum machines struggle with, do not rely on quantum-vulnerable elliptic curves.
But quantum-resistant ZK samples are larger and heavier than today’s versions. This makes them harder to store and more expensive to verify on blockchains with tight space constraints. But the benefit is huge: they offer a way to protect billions of assets on the chain without need an immediate, risky overhaul of the base protocol.
In other words, ZK blockchains provide a flexible upgrade path. Instead of ripping out their entire signature system overnight, networks could gradually add quantum-safe ZK proofs to transactions—allowing old and new cryptography to coexist during the transition period.
The quantum advantage of Web3
Today’s computers can only fake coincidences. They use formulas to generate “random” numbers, but these numbers are ultimately produced by a predictable process. This means that parts of a blockchain system – like choosing which validator to propose the next block, or determining the winner of a decentralized lottery – can be subtly influenced to the financial advantage of bad actors. But earlier this year, quantum researchers achieved a remarkable milestone: certified randomness.
Quantum systems exploit natural, unpredictable phenomena such as the spin of a photon or the decay of a particle. This is true, unforgettable randomness, something classical computers cannot deliver.
For blockchains, this is a big deal. The Web3 ecosystem needs a public, quantum-powered randomness beacon to see the core mechanisms that make blockchains tick. With quantum we can build one that is fair, tamper proof and impossible to tamper with. A solution that would address longstanding deficiencies in decentralized lotteries and validator selection.
Here lies the question. Will Web3 get serious about quantum-resistant cryptography before quantum computers come of age? History suggests that base-layer upgrades to major blockchain protocols can take years, in part due to the lack of central coordination inherent in decentralized systems. However, the industry cannot afford to wait for quantum to breach ECDSA before taking action.
We can argue about the exact timeline, but the quantum future is a near certainty. ZK can protect Web3 through this transition and turn quantum threats into quantum opportunities.
The time to act is now while we still can.
