A new a16z crypto research paper is reshaping the conversation around quantum threats to Bitcoin. While many fear an abrupt collapse triggered by a powerful quantum computer, the report argues that reality is far more complex. Instead of a sudden failure, the true danger may come from a long, challenging transition to post-quantum security.
Justin Thaler, a Georgetown professor and research partner at a16z, says the industry often exaggerates timelines for quantum breakthroughs. He warns that this misplaced focus diverts attention from immediate risks—especially implementation errors that can occur as developers begin preparing for quantum-resistant upgrades. Thaler defines a “cryptographically relevant quantum computer” (CRQC) as a machine capable of breaking RSA-2048 within a month. He believes such a machine remains unlikely to appear during the 2020s.
Thaler also explains that Bitcoin’s cryptographic exposure differs from traditional encrypted systems. While post-quantum encryption is essential for protecting sensitive, long-term data, Bitcoin signatures don’t conceal hidden information, so the nature of their vulnerability is unique.
Experts Warn That Blockchains Are Attractive Quantum Targets
Crypto analysts including Nic Carter and Alex Pruden strongly disagree with Thaler’s cautious timeline. They argue that the quantum threat is more imminent than the research suggests, emphasizing that public blockchains are especially high-value targets. Because public keys are directly linked to digital assets, even partial quantum capabilities could be enough to cause significant disruption.
These critics stress that the industry cannot afford to wait. The migration to post-quantum cryptography will be technically demanding, slow to implement, and require coordination across global decentralized networks. Delaying preparations could lead to panic, rushed upgrades, or fragmented solutions.
The Biggest Quantum Risk: A Difficult, Multi-Year Migration
The growing debate underscores a crucial takeaway: Bitcoin is unlikely to vanish overnight because of a quantum breakthrough. Instead, the real threat lies in the lengthy and complex process of moving the entire ecosystem to post-quantum security standards. Whether quantum timelines are short or long, the blockchain industry will need years of planning, testing, and collaboration to complete this migration safely.
Preparing early—not for sudden collapse, but for gradual transition—may ultimately be the key to securing Bitcoin and other blockchains in a post-quantum future.
