According to @Andre_Dragosch, Bitcoin’s network security is not the near-term weak point; the main quantum risk is to legacy wallets with exposed public keys that could be derived via Shor’s algorithm once sufficiently powerful hardware exists, not via brute-force of private keys, which is infeasible today, source: @Andre_Dragosch on X. For context, Google’s Willow system has 105 physical qubits, while breaking Bitcoin’s ECC would likely require roughly 5,000–10,000 logical qubits, implying hundreds of thousands to millions of physical qubits, placing the threat multiple engineering breakthroughs away, source: @Andre_Dragosch on X. Bitcoin’s network currently runs at about 1 zettahash per second, vastly beyond the reach of current quantum machines and expected capabilities in the foreseeable future, reinforcing low network-level risk for traders, source: @Andre_Dragosch on X. The concentrated exposure lies in older addresses: estimates suggest 4.5M+ BTC sit in dormant wallets that may never upgrade to quantum-resistant signatures, and a forced migration or sudden movement of these coins could create material sell pressure, source: @Andre_Dragosch on X. Timeline opinions vary widely, with ranges cited as 2029, around a 20% chance by 2030, and 2045–2065, highlighting uncertainty but also time for Bitcoin to implement quantum-safe BIPs and coordinate upgrades, source: @Andre_Dragosch on X citing @caprioleio, @VitalikButerin, and @adam3us. For trading strategy, the takeaway is low near-term quantum risk to BTC’s consensus while monitoring on-chain activity of Satoshi-era and other legacy wallets for unusual spending that could signal supply overhang, plus tracking progress on quantum-resistant BIPs as a mitigating catalyst, source: @Andre_Dragosch on X. Traditional finance may face quantum risk earlier due to widespread RSA/ECC usage in authentication and interbank communications, which, if compromised, could shift relative risk perceptions and support BTC’s digital bearer asset narrative, source: @Andre_Dragosch on X.

According to the source, headlines about Saudi Arabia’s first quantum computer have raised concerns about whether BTC can be broken, but current devices lack the large-scale, fault-tolerant logical qubits needed to run Shor’s algorithm against Bitcoin’s secp256k1 ECDSA at practical speeds, keeping immediate quantum risk low for traders; source: NIST 2022 PQC selections; IBM Quantum roadmap 2023–2024; National Academies 2019. Breaking a single 256-bit ECDSA key is estimated to require thousands of logical qubits and over 10^9 T-gates, implying millions of physical qubits with surface-code error correction—orders of magnitude beyond today’s hardware; source: Roetteler et al. 2017; Fowler et al. 2012; Gidney and Ekerå 2019. Bitcoin only reveals a public key when coins are spent, so UTXOs in non-reused addresses remain shielded from quantum key-recovery until broadcast, concentrating any near-term vulnerability on exposed or reused keys; source: Antonopoulos, Mastering Bitcoin (2nd ed.); Aggarwal et al. 2017. For positioning, treat quantum as a monitoring catalyst rather than an immediate tail risk, and watch credible milestones such as thousands of stable logical qubits and NIST’s PQC FIPS finalization that would signal migration timing; source: NIST 2024 draft FIPS 203/204; National Academies 2019. If a cryptographically relevant quantum computer emerges, assets tied to exposed public keys and reused addresses would face the earliest risks, reinforcing UTXO hygiene and readiness to upgrade wallets once PQC paths are standardized; source: Aggarwal et al. 2017; Bitcoin developer documentation.

According to the source, the core quantum threat to Bitcoin is that a sufficiently large fault-tolerant quantum computer running Shor’s algorithm could derive private keys from revealed ECDSA or Schnorr public keys, enabling unauthorized spends, while this is not feasible with today’s machines. source: Shor 1997; Bitcoin.org Developer Guide; BIP340 2020. UTXOs whose public keys have not been revealed on-chain are more resilient in the near term because address protection relies on hash preimages where Grover’s algorithm provides only a quadratic speedup, preserving roughly 128-bit security for SHA-256-based constructions. source: NISTIR 8105 2016; Bitcoin.org Developer Guide. There is currently no practical quantum computer capable of breaking Bitcoin’s public-key cryptography, but NIST finalized post-quantum standards in 2024 (ML-KEM, ML-DSA, SLH-DSA) that can guide migration paths for future signature schemes. source: NIST FIPS 203–205, 2024. Traders should monitor any BIPs proposing post-quantum signature types and watch for unusual spends from legacy P2PK or long-dormant outputs, as coordinated migrations can elevate on-chain congestion and fees that impact execution and volatility. source: BIP341 2021; Bitcoin Wiki Pay to Pubkey; Bitcoin.org Transactions–Fees.

According to the source, Q-Day describes the point when cryptographically relevant quantum computers can use Shor’s algorithm to break Bitcoin’s ECDSA and Schnorr signatures, endangering funds once their public keys are exposed; source: Shor 1994; source: BIP340; source: Bitcoin Wiki (Quantum computing and Bitcoin). For Bitcoin specifically, coins become vulnerable only after a spend reveals the public key, while unspent outputs with unrevealed keys retain stronger pre-spend safety; source: Bitcoin.org Developer Guide; source: Bitcoin Wiki. Early P2PK outputs and any reused addresses that have exposed public keys are structurally more at risk if a sufficiently powerful quantum computer emerges; source: Bitcoin Wiki; source: Bitcoin.org Developer Guide. No quantum computer currently exists that can break 256-bit ECC in practice, and NIST finalized the first post-quantum cryptography standards in 2024 to guide migration (ML-KEM, ML-DSA, SLH-DSA), indicating preparation rather than immediate breakage; source: NIST 2024 FIPS 203–205. U.S. national security guidance targets migration to post-quantum algorithms over the coming decade, underscoring a medium- to long-term threat horizon for public-key systems like ECDSA/Schnorr; source: NSA CNSA 2.0, 2022. For traders, key watchpoints include Bitcoin Core and BIP discussions on introducing post-quantum signature types via soft fork (demonstrated feasible by past upgrades like Taproot), the share of UTXOs with exposed public keys, and NIST/industry PQC adoption milestones; source: BIP341 Taproot; source: Bitcoin Wiki; source: NIST 2024. A credible roadmap to post-quantum migration and on-chain movement to new address types would be a critical market catalyst for BTC volatility and fees, making custody policies that minimize key exposure and reuse a prudent risk control; source: Bitcoin Wiki; source: Bitcoin.org Developer Guide.