Vaulted CEO David McAlvany said Bitcoin could disappear within the next four years because of advances in quantum computing, according to Forbes, though he also acknowledged he cannot say when such a breakthrough might actually arrive. He said Bitcoin would face an existential problem if quantum machines become capable of quickly solving the mathematical problems that protect private keys. As of mid-2026, however, no quantum computer exists that can break Bitcoin’s cryptography. The concern described in the report is tied to the pace of future quantum development rather than any security breach that has already happened. Estimates cited in the report show that a large share of BTC sits in addresses with exposed public keys: Galaxy Digital put the number at about 7 million BTC, worth roughly $470 billion, while Glassnode estimated 6.04 million BTC, or 30.2% of supply. The report also outlined an active debate over how Bitcoin should respond. BIP-360 would add quantum-resistant address types, while BIP-361 would phase out old signature support, a move that could permanently freeze coins that are not migrated in time. Supporters say that outcome would be preferable to theft and forced selling by quantum attackers, while critics see it as confiscation.

AmericanFortress, a Wyoming-based blockchain security and cryptography firm focused on post-quantum security, has published research outlining a way for Bitcoin and other blockchain wallets to defend against future quantum attacks without forcing users to move funds to new addresses. In a paper titled “ZKPoSP: Post-Quantum Zero-Knowledge Proofs for Hierarchical Deterministic Wallets,” the team proposes replacing traditional elliptic-curve signatures with zero-knowledge proofs while preserving compatibility with hierarchical deterministic wallet standards. The paper centers on the industry’s so-called Q-Day scenario, when a fault-tolerant quantum computer could run Shor’s algorithm to derive private keys from public keys. The authors argue that, instead of relying on exposed key pairs, wallet owners could prove control through the wallet seed phrase without revealing the seed itself. The study introduces ZKPoSP and a key derivation approach called QBIP32, and reports prototype benchmarks built in Rust with the RISC Zero zero-knowledge virtual machine. AmericanFortress said proof generation took about 12 to 13 seconds, while verification took roughly 9 to 10 milliseconds. The system has not been adopted by any blockchain network, and deployment would require support from developers, wallet providers, exchanges, miners, and users. The research arrives as post-quantum security efforts across the crypto sector continue to accelerate.

A Citi report says quantum computing could weaken current cryptography, putting 6.5 million to 6.9 million BTC with exposed keys at risk, equal to about $450 billion at current prices.

Citi says advances in quantum computing are shortening the timeline for crypto security risks, with 6.5 million to 6.9 million BTC exposed through public keys and potentially vulnerable in the future.

Google has set 2029 as its target for post-quantum cryptography across its products, citing faster progress in quantum hardware and error correction. Ethereum, Bitcoin and Solana are taking notably different paths in response to the same threat.

Google plans to complete its post-quantum cryptography migration by 2029, six years ahead of the U.S. federal target. Ethereum, Solana, and Bitcoin communities are responding with sharply different strategies.

A new Bitcoin proposal, BIP-361, would push users to migrate funds to quantum-resistant addresses. Coins left in legacy wallets could eventually become unspendable under a phased plan.

Project Eleven CEO Alex Pruden said at Consensus Miami that Bitcoin's post-quantum migration is more complex than the Taproot upgrade and needs to begin immediately. Delay risks $2.3 trillion in assets; a quantum computer could steal funds in a single block if users haven't migrated.