Cardano’s Hoskinson warns that making crypto post-quantum will require trade-offs

As blockchain developers debate protocol updates to counter possible future quantum attacks, Cardano founder Charles Hoskinson said the central issue is timing, not what changes to make. He warns that acting too quickly can impose high costs on blockchain networks.

According to Hoskinson, the cryptographic tools needed to protect blockchains against future quantum attacks already exist, pointing to post-quantum standards released by the US National Institute of Standards and Technology in 2024. The problem Hoskinson explained is what it would cost if the new protocols are implemented before miners and validators are ready.

“Post-quantum crypto is often about 10 times slower, 10 times larger trial size and 10 times more inefficient,” Hoskinson told Declutter. “So when you adopt it, you’re essentially taking the throughput of your blockchain and reducing it by cutting off a zero.”

While researchers broadly agree that sufficiently powerful quantum computers could one day break modern-day cryptography, there is much less agreement on when that threat will become real. Estimates predict that the arrival of a practical quantum computer will be several years to more than a decade away.

Hoskinson said that rather than focusing on hype and corporate timelines when assessing how quickly the threat could emerge, a better option would be to pay attention to DARPA’s Quantum Benchmarking Initiative, which tests whether different quantum computing approaches can produce useful results.

“It is the best independent, objective measure that can be referenced to determine whether quantum computers will be real or not, when they will hit and who will create them,” he said.

DARPA has set 2033 as a target year to determine whether utility-scale quantum computing is feasible.

Like most major networks, including Bitcoin, Ethereum, and Solana, Cardano relies on elliptic curve cryptography, which could theoretically be broken by Shor’s algorithm if sufficiently powerful quantum computers emerge. Hoskinson said the industry already knows how to address this vulnerability, but said the debate came down to a choice between two competing cryptographic approaches.

“There are two big bets you can make,” Hoskinson said. “Hashes, that’s what Ethereum makes, and lattices, that’s what we make.”

Hash-based cryptography uses cryptographic hash functions to create digital signatures that are widely seen as safe from future quantum attacks. These systems are simple, well-studied, and conservative in design, but are primarily used for data signing and are not suitable for general-purpose encryption.

Lattice-based cryptography is based on hard mathematical problems that are expected to remain difficult even for quantum computers. Lattice cryptography supports not only digital signatures, but also encryption and more advanced cryptographic tools, which proponents say make it better suited for a post-quantum world.

“You can do all your crypto operations on your graphics card, just like you would do an AI operation,” he said. “So you can reuse hundreds of billions of dollars of AI computers, and you don’t have to build ASICs to speed these things up.”

However, Hoskinson did not call for an immediate protocol-wide change in favor of one method or the other. Instead, he described a phased mitigation approach. One option he noted was to create post-quantum signed checkpoints of Cardano’s ledger history using systems like Mithril and the privacy-focused Midnight sidechain.

“There are always tradeoffs with these systems,” he said. “You can’t go from immediate finality to probabilistic finality. Once you’ve made that decision, you’ve made that decision and you live with the consequences.”