Cardano Founder’s Stark Warning: Post-Quantum Crypto Could Slash Blockchain Speed by 90%

Charles Hoskinson just dropped a quantum-sized bombshell on crypto's future.

The Cardano founder warns that integrating post-quantum cryptography—the kind designed to withstand attacks from tomorrow's supercomputers—could cripple blockchain performance. We're talking a potential 90% reduction in transaction speed. That's not an upgrade; it's a traffic jam at the atomic level.

The Quantum Conundrum: Security vs. Speed

It's the ultimate trade-off. Quantum-resistant algorithms are complex beasts. They require heavier computational lifting, which translates directly to slower validation times and bloated block sizes. For networks built on speed and efficiency, this isn't a minor tweak—it's a fundamental re-architecture.

Hoskinson's warning cuts through the usual techno-optimism. It forces a brutal question: are we building fortresses so secure that nothing can get in or out? A blockchain that's 100% quantum-safe but processes transactions at a dial-up modem's pace isn't just impractical; it's useless for a global financial system.

The Looming Deadline

This isn't a distant sci-fi problem. Governments and corporations are already stockpiling quantum-resistant algorithms. The crypto ecosystem can't afford to wait until a quantum computer breaks Bitcoin's SHA-256 to start panicking. The research, testing, and implementation need to happen yesterday. Yet, the industry remains fragmented, often prioritizing the next meme coin pump over this existential tech debt.

Finding the Balance

The path forward isn't binary. Hybrid solutions—mixing classical and post-quantum cryptography—offer a middle ground. So do layer-2 scaling solutions designed to handle the heavy lifting off-chain. But each compromise introduces new complexities and potential vulnerabilities. The race is on to build a vault that's both impenetrable and has a functioning door.

Hoskinson's 90% figure is a wake-up call, not a death sentence. It highlights the massive engineering challenge ahead. The projects that start solving for this now, balancing ironclad security with real-world usability, will be the ones left standing. The rest? They'll be secure, slow, and utterly irrelevant—a perfect hedge for investors who think digital gold should actually be as slow as digging up the real stuff.

TLDR

• Cardano founder Charles Hoskinson warns that implementing post-quantum cryptography now would reduce blockchain throughput by 90% due to slower processing and larger proof sizes.
• Post-quantum cryptographic standards already exist from NIST as of 2024, but the timing of implementation remains the key challenge for blockchain networks.
• DARPA has set 2033 as a target year to determine if utility-scale quantum computing is feasible through its Quantum Benchmarking Initiative.
• The industry faces a choice between two post-quantum approaches: hash-based cryptography (Ethereum’s direction) and lattice-based cryptography (Cardano’s preference).
• Hoskinson suggests a staged mitigation approach using post-quantum-signed checkpoints rather than immediate protocol-wide changes to address the quantum threat.

Charles Hoskinson, founder of Cardano, has outlined the challenges blockchain networks face in preparing for potential quantum computer attacks. He says the main issue is not what changes to make but when to make them.

Charles Hoskinson said post-quantum cryptography was standardized in 2024 by the National Institute of Standards and Technology, but warned that without hardware acceleration it could reduce blockchain performance by roughly an order of magnitude. He added that the key issue is…

— Wu Blockchain (@WuBlockchain) December 21, 2025

The cryptographic tools needed to protect blockchains from quantum threats already exist. The U.S. National Institute of Standards and Technology released post-quantum standards in 2024.

However, Hoskinson warns that implementing these protocols too early could harm blockchain performance. Post-quantum cryptography is about 10 times slower and creates proof sizes that are 10 times larger.

“If you adopt it, what you’re basically doing is taking the throughput of your blockchain and reducing it by cutting off a zero,” Hoskinson told Decrypt. This means blockchains could lose 90% of their current processing capacity.

The debate over quantum threats centers on timing. Researchers agree that powerful quantum computers could eventually break current cryptographic systems.

Estimates for when this threat becomes real vary widely. Some predictions suggest a few years while others point to more than a decade away.

No, quantum computers won't break Bitcoin in the near future. We'll keep observing their evolution.

Yet, making thoughtful changes to the protocol (and an unprecedented migration of funds) could easily take 5 to 10 years.

We should hope for the best, but prepare for the worst.

— Jameson Lopp (@lopp) December 21, 2025

Hoskinson recommends following DARPA’s Quantum Benchmarking Initiative instead of corporate timelines. The initiative tests whether different quantum computing approaches can deliver useful results.

DARPA has set 2033 as the target year for determining if utility-scale quantum computing is feasible. Hoskinson called this “the best independent, objective benchmark” for tracking quantum computer development.

Current Cryptography Vulnerabilities

Most major blockchain networks use elliptic-curve cryptography. This includes Bitcoin, Ethereum, Solana, and Cardano.

Shor’s algorithm could theoretically break this cryptography if powerful enough quantum computers emerge. The industry already knows how to address this vulnerability.

Two Competing Approaches

The blockchain industry faces a choice between two post-quantum cryptographic methods. Hash-based cryptography uses cryptographic hash functions to create digital signatures that resist quantum attacks.

These systems are simple and well-studied. However, they work mainly for signing data and cannot handle general-purpose encryption.

Ethereum is pursuing the hash-based approach. Lattice-based cryptography relies on difficult mathematical problems that should remain secure against quantum computers.

Cardano plans to use lattice-based methods. This approach supports digital signatures, encryption, and other advanced cryptographic tools.

Hoskinson said lattice cryptography can run on graphics cards like AI operations. This means networks can reuse existing AI computer infrastructure worth hundreds of billions of dollars.

Staged Implementation Strategy

Hoskinson did not call for immediate protocol-wide changes. He described a staged mitigation approach as a better option.

One possibility involves creating post-quantum-signed checkpoints of Cardano’s ledger history. This could use systems like Mithril and the Midnight sidechain.

“There are always trade-offs with these systems,” Hoskinson said. He noted that fundamental decisions about finality cannot be reversed once made.