Project Eleven released a report warning that quantum computers capable of breaking blockchain cryptography could arrive by 2030, with a baseline Q-Day scenario projected for 2033. Google researchers found that breaking Bitcoin's elliptic curve cryptography would require roughly 1,200 logical qubits and under 90 minutes of computing time. Approximately 6.9 million Bitcoin (one-third of total supply) and over 65% of all ETH sit in quantum-exposed addresses vulnerable to attack, with no fraud protection or reversal mechanisms available on blockchains. While traditional internet infrastructure has rapidly adopted post-quantum encryption—over half of web traffic is now protected—blockchain migrations face governance challenges, as illustrated by Bitcoin SegWit's contentious two-year upgrade process and Ethereum's six-year proof-of-stake transition.
Quantum computing threat timeline and capabilities
- ▪Google published a 2029 post-quantum migration timeline; it did not set Q-Day at 2032
- ▪Shor's algorithm is 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 required by classical computers
- ▪Project Eleven published a report warning that a cryptographically relevant quantum computer capable of breaking blockchain cryptography is more likely than not to exist by 2033
- ▪Google researchers found in a March paper that breaking 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
- ▪Project Eleven's report estimates that a cryptographically relevant quantum computer could arrive as early as 2030
Vulnerability of blockchain networks to quantum attacks
- ▪Over 65% of all ETH is held in quantum-exposed addresses on Ethereum
- ▪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
Challenges and slow progress of quantum-resistant migration
- ▪CNSA 2.0 applies specifically to National Security Systems and uses phased milestones in 2030, 2031 and 2035
- ▪Cloudflare reported that a majority of human-initiated traffic handled by Cloudflare used post-quantum encryption, not a majority of all web traffic
- ▪The Bitcoin SegWit upgrade took more than two years from proposal to activation and triggered a contentious chain split
- ▪Apple enabled hybrid post-quantum support across its devices in iOS 26
- ▪Migrating all Bitcoin UTXOs to quantum-resistant addresses would take approximately 76 days if 100% of block space were dedicated to that effort
Perspective of Project Eleven
- ▪Project Eleven warns that quantum computers capable of breaking blockchain cryptography could arrive as soon as 2030
Perspective of Cryptocurrency holders with exposed public keys
- ▪Over 65% of all Ether is held in quantum-exposed addresses; this is a share of ETH supply, not a share of Ethereum holders
- ▪Approximately 6.9 million BTC — about one-third of the total possible supply — sits in addresses whose public keys have already been exposed on-chain; the figure counts bitcoin, not holders
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