Bitcoin, Ethereum ‘Q-Day’ Quantum Threat Could Arrive as Soon as 2030: Report – Decrypt

A sweeping new technical report warns that the cryptographic foundations securing trillions of dollars in digital assets could be broken by quantum computers within the next four to seven years—and that the blockchain industry is dangerously unprepared for the transition needed to survive.

The report, published by Project Eleven, a quantum security firm, concludes that a “cryptographically relevant quantum computer”—one powerful enough to crack the elliptic curve digital signatures protecting Bitcoin, Ethereum, and other major blockchains—is more likely than not to exist by 2033, and potentially as early as 2030.

The window for action, the authors argue, is rapidly closing.

“Migration to quantum-resistant cryptography is no longer optional but imperative for any blockchain system expected to be trusted and secure into the future,” the report states.

The threat centers on Shor’s algorithm, a quantum computing technique first described in 1994 that can solve the mathematical problem underpinning most modern public-key cryptography in a fraction of the time it would take classical computers. Recent breakthroughs have dramatically lowered the hardware bar required to run such an attack.

A head-turning March paper from Google researchers found that breaking the elliptic curve cryptography used by Bitcoin could be accomplished using roughly 1,200 logical qubits and fewer than 90 minutes of computing time on superconducting hardware.

Google put its target for “Q-Day,” or the time at which a quantum computer hits the market that’s powerful enough to break modern cryptography, at 2032. Project Eleven’s analysis accelerates that timeline by potentially two years.

The report estimates that approximately 6.9 million Bitcoin—about one-third of the total possible supply—sits in addresses whose public keys have already been exposed on-chain, making them potentially vulnerable to quantum attack. On Ethereum, the exposure is even broader: analysts have found that over 65% of all ETH is held in quantum-exposed addresses.

What makes blockchains particularly vulnerable, the report explains, is that their public ledgers and bearer-instrument design offer no safety net. Unlike a bank, a blockchain has no fraud department, no chargeback mechanism, and no way to reverse a forged transaction. Once a quantum attacker recovers a private key and drains a wallet, the loss is permanent.

The migration challenge is compounded by the slow-moving nature of blockchain governance. The Bitcoin SegWit upgrade—a relatively modest protocol change—took more than two years from proposal to activation, and triggered a contentious chain split. Ethereum’s transition to proof-of-stake required roughly six years of development. A quantum migration would touch the most fundamental cryptographic layer of any blockchain protocol.

Even under the most optimistic assumptions, the report estimates that migrating all Bitcoin UTXOs (or unspent transaction outputs) to quantum-resistant addresses—if 100% of block space were dedicated to that effort—would take approximately 76 days. As migration competes with ordinary economic activity, timelines extend significantly.

The rest of the technology world has already begun moving. Over half of all human web traffic is now post-quantum encrypted, according to Cloudflare data from December 2025. OpenSSH defaults to post-quantum key exchange, while Apple enabled hybrid post-quantum support across its devices in iOS 26. The National Security Agency has set a 2030–2033 target for complete migration across government systems.

A researcher has used a publicly accessible quantum computer to crack a vastly simplified version of a Bitcoin-style cryptographic key, marking the largest public demonstration yet of a quantum attack on elliptic curve cryptography.
Project Eleven said Friday it awarded its 1 Bitcoin “Q-Day Prize” bounty—currently worth nearly $78,000—to Italian researcher Giancarlo Lelli for breaking a 15-bit elliptic curve cryptography key using a variant of Shor’s algorithm.
“I joined out of a mix of wanting…

The digital asset industry, by contrast, has barely started. Bitcoin developers are weighing numerous proposals, both formal and otherwise, while the Ethereum Foundation has formed a team that’s working to design and coordinate the network’s path to post-quantum security. But as noted, those plans could take years to execute, once developers agree upon any approach.

“The internet has already moved,” the report concludes. “The digital asset industry—which arguably has more at stake because blockchains directly protect bearer value with the exact cryptographic primitives that quantum computers threaten—has barely started.”

The authors recommend that blockchain networks begin immediate cryptographic inventories, deploy post-quantum key exchange in off-chain infrastructure without delay, and start the complex governance and design work needed for on-chain signature upgrades—warning that by the time the threat feels urgent, there will no longer be enough time to respond.